Author's personal copy
Review Article
Recent developments in planetary Aeolian studies and their terrestrial
analogs
J.R. Zimbelman a,?, M.C. Bourke b, R.D. Lorenz c
aCenter for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC 20013-7012, USA
b Planetary Science Institute, 1700 E Ft. Lowell, Suite #106, Tucson, AZ 85719, USA
c Space Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD 20723, USA
a r t i c l e i n f o
Article history:
Received 16 March 2012
Revised 15 April 2013
Accepted 15 April 2013
Available online 10 July 2013
Keywords:
Sand dunes
Ripples
Sediment transport
Bedforms
Saltation
a b s t r a c t
This report summarizes the many advances that have been made in the study of planetary Aeolian pro-
cesses that have taken place since the ?rst Planetary Dunes Workshop was held in May of 2008, through
2011. Many of the recent studies are facilitated by the wealth and variety of high resolution imaging and
spectra data still being returned by multiple spacecraft in orbit and on the surface of Mars, as well as Cas-
sini radar and imaging data for the unique linear dunes on Titan, the large moon of Saturn. The report is
divided into seven broad topics: exploring the Martian rock record, the action of the wind, sediment com-
position, sediment transport, Aeolian bedforms, modi?cation processes, and Titan. Analog studies of ter-
restrial landforms and processes continue to improve our understanding of the operation of Aeolian
processes on other planetary surfaces in each of these topics. Four subjects are likely to see increased
emphasis during the coming years: Martian aeolianites, sand compositional diversity, active versus inac-
tive features, and deposition versus erosion. Continued growth of the planetary Aeolian literature is
expected as several spacecraft continue to provide high-quality data, including the successful arrival of
the Curiosity rover at Mars in August of 2012.
Published by Elsevier B.V.
Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
2. Exploring the Martian rock record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
3. The action of the wind. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
4. Sediment composition on Mars. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
5. Sediment transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.1. Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.2. Mars observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.3. Lab simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
5.4. Analogs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
6. Aeolian features on Mars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
6.1. Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
6.2. Transverse Aeolian Ridges (TARs). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
6.3. Active bedforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
6.4. Inactive bedforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6.5. Wind-related erosional features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6.6. Analogs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7. Modification processes on Mars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
8. Titan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
9. Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
9.1. Significant developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
9.1.1. Martian aeolianites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
1875-9637/$ - see front matter Published by Elsevier B.V.
http://dx.doi.org/10.1016/j.aeolia.2013.04.004
? Corresponding author. Tel.: +1 202 633 2471; fax: +1 202 786 2566.
E-mail addresses: zimbelmanj@si.edu (J.R. Zimbelman), mbourke@psi.edu
(M.C. Bourke), ralph.lorenz@jhuapl.edu (R.D. Lorenz).
Aeolian Research 11 (2013) 109?126
Contents lists available at ScienceDirect
Aeolian Research
journal homepage: www.elsevier .com/locate /aeol ia
Author's personal copy
9.1.2. Sand compositional diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
9.1.3. Active versus inactive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
9.1.4. Deposition versus erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
9.2. Gale crater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
1. Introduction
Aeolian studies encompass a range of processes and landforms
that are the result of the interaction between the wind and the
rocks or soils that comprise the surface materials. The work of
the wind on the surface is primarily accomplished through the mo-
tion of loose particles induced by the wind ?ow over them (e.g.,
Bagnold, 1941; Greeley and Iversen, 1985; Lancaster, 1995),
although some would argue that wind alone is capable of produc-
ing geomorphic work (e.g., Whitney, 1978). Distinctive landforms
result from various Aeolian processes, including (but certainly
not limited to) sand ripples, various types and shapes of sand
dunes, yardangs (bedrock materials eroded into a myriad of
shapes), ventifacts (rocks abraded by the wind and sand), loess
(dust deposits), sand sheets, and certain gravel plains. If loose par-
ticles and wind suf?cient to move them is readily available, Aeo-
lian activity is not restricted to only the surface of the Earth.
Robotic spacecraft missions to the planets have revealed how pre-
valent Aeolian deposits and landforms are on practically any solid
planetary surface possessing an atmosphere, and in particular a
host of recent spacecraft have examined the Martian surface in
unprecedented detail, leading to new documentation of many Aeo-
lian features across the Red Planet. Supplementary to these won-
derful new data sets from the planets, an improved
understanding of the details associated with how certain Aeolian
features form and evolve often requires careful observation and
instrumentation of terrestrial analogs for features observed on
other planets. The purpose of this report is to provide a brief review
of recent developments in Aeolian studies of planetary bodies,
along with recent studies of analog sites for some planetary land-
forms and deposits.
Studies of Aeolian processes throughout the solar system have
bene?ted greatly from two recent NASA-supported workshops de-
voted to this subject. The ?rst Planetary Dunes Workshop was held
in Alamagordo, New Mexico, during May of 2008, where about 50
participants presented research results and also took part in a one-
day ?eld excursion to nearby White Sands National Monument (Ti-
tus et al., 2008a,b). Participants included roughly equal numbers of
researchers focused either on the study of planetary Aeolian fea-
tures or investigations of diverse planetary Aeolian environments;
the synergistic interchange between these groups resulted in the
identi?cation of several speci?c subject areas needing further
study in the future (Titus et al., 2008b). This ?rst workshop re-
sulted in publication of a special issue of Geomorphology (Septem-
ber, 2010) containing nine papers dealing with a wide range of
Aeolian topics, including a paper that served both as an introduc-
tion to the special issue and as a review of planetary Aeolian stud-
ies up to the time of the ?rst workshop (Bourke et al., 2010). The
Second Planetary Dunes Workshop was held in Alamosa, Colorado,
during May of 2010, where about 60 participants from both the
planetary and terrestrial Aeolian communities presented results
and took part in a one-day ?eld excursion to nearby Great Sand
Dunes National Park and Preserve (Titus et al., 2010; Fenton
et al., 2010). Plans are in place for a special issue of Earth Surface
Processes and Landforms to publish papers built around work pre-
sented at the second workshop. The present report is restricted
to a discussion of various published results that came after the ?rst
workshop, through all of 2011 (with only sparing citation of later
work that bears directly upon the results being discussed). Readers
are referred to Bourke et al. (2010) for treatment of results prior to
and including the ?rst workshop, and to Greeley and Iversen
(1985), Lancaster (1995, 2009) for more in-depth discussion of a
host of earlier Aeolian studies.
This review is divided into seven broad topics or themes:
exploring the Martian rock record, the action of the wind, sediment
composition (including possible sources), sediment transport, Aeo-
lian bedforms, modi?cation processes (particularly gullies on
dunes), and Titan. The ?rst six topics are dominated by results de-
rived from the new data from Mars, but the seventh topic indicates
that the on-going Cassini mission continues to reveal surprises
about the intriguing but perplexing dunes on Titan. Venus is not
mentioned here because most of the Aeolian studies for this planet
resulted from the Magellan mission in the early 1990s, as reviewed
in Bourke et al. (2010), and there are no major revisions at present
to the Magellan conclusions. Relevant terrestrial analog studies are
covered under each topic that is most closely associated with the
reported results, emphasizing terrestrial projects that have a par-
ticularly strong potential as analogs for the interpretation of plan-
etary Aeolian features. However, the reader should be cognizant
that this report is not intended to represent a thorough review of
recent terrestrial Aeolian studies; see Livingstone et al. (2007) for
an excellent review of recent studies of terrestrial dunes.
2. Exploring the Martian rock record
There is considerable evidence that the rock record on Mars in-
cludes many examples of sedimentary (layered) deposits (e.g., Mal-
in and Edgett, 2000), some of which are more likely the result of
transportation by the wind as opposed to deposition out of water.
Perhaps the most dramatic evidence of massive wind-driven sand-
stones comes from the Opportunity rover?s explorations in the
Meridiani Planum region of Mars. In particular, exposures in Victo-
ria crater reveal dramatic examples of cross-bedded sandstones
(Fig. 1) that are at least a dozen meters in thickness (Squyres
et al., 2009; Hayes et al., 2011), greatly expanding the stratigraphic
thickness of the Aeolian sandstones seen earlier in Endurance cra-
ter (Grotzinger et al., 2005). Opportunity also found evidence of
dunes with a strong sulfate signature (perhaps more the result of
pore-?lling materials than of the sand itself), with wet interdune
areas, during exploration of Erebus crater (Metz et al., 2009).
Hematite concretions within the sulfate-bearing sandstones are
interpreted to indicate that a considerable ?ow of groundwater
took place through the sandstones following their emplacement
(Squyres et al., 2004a). Orbital data are providing evidence that
the discoveries made by Opportunity likely represent large por-
tions of Meridiani Planum (Hynek and Phillips, 2008). Sedimentary
rocks derived from wind-blown sands thus appear to represent a
110 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126
Author's personal copy
very important part of the early history of Mars (Squyres et al.,
2009); such rocks may be far more widespread around the planet
than would have been considered likely prior to the in situ inves-
tigations by Opportunity.
High resolution orbital imaging has revealed that layered rock
outcrops are present across Mars at a variety of scales (e.g., Brown
et al., 2008; Lewis et al., 2008; Malin et al., 2010; McEwen et al.,
2010; Milliken et al., 2010), including the basal unit of the north
polar layered deposits (Selvans et al., 2010) and the exhumed but
cratered south polar layered deposits (Kolb and Tanaka, 2001; Fen-
ton and Hayward, 2010). Some outcrops include cross-bedding and
unconformities clearly visible even from orbital altitudes (Fig. 2;
Malin et al., 2010), interpreted to be the result of Aeolian deposi-
tion and erosion. Image coverage in places is now suf?cient to al-
low detailed stratigraphic columns to be developed for large
layered deposits. For example, within the 154-km-diameter Gale
crater basin is a 5-km-tall central mound where an unconformity
correlates to major changes in rock composition, signaling a
change from sulfate- and clay-rich deposits near the base to uni-
formly layered deposits with a composition similar to that of the
Martian dust at the upper portions of the mound (Milliken et al.,
2010). The Gale crater location is destined to reveal much about
the history of Mars preserved in these layered rocks as the Curios-
ity rover explores the Gale mound. Orbital spectrometer measure-
ments are allowing investigators to dissect layered deposits
present within Candor Chasma, one portion of the huge Valles
Marineris canyon system near the equator of Mars; contrary to
the situation at Gale crater, many of the Candor Chasma layered
rocks give no indication that water must have been involved in
their emplacement (Murchie et al., 2009a,b). Dusty regions on
Mars, including broad areas surrounding the enormous shield vol-
canoes which comprise the Tharsis Montes, northwest of the Valles
Marineris canyons, have a complex surface texture that is inter-
preted to perhaps result from wind action on sand-sized aggre-
gates of dust, some of which eventually lithify to form what may
be an Aeolian version of a claystone (Bridges et al., 2010). A possi-
ble terrestrial analog to such aggregate wind-blown materials is
parna, an Australian word for silt?clay aggregates that undergo sal-
tation and form crescentic dunes around ephemeral playa-lakes;
subsequent rain can break down the aggregates to leave silt?
clay-rich deposits in the crescentic shape of the former dunes
(Greeley and Williams, 1994).
3. The action of the wind
The wind is the primary present-day (non-?uvial) agent of
movement of materials on terrestrial planets with atmospheres
(Craddock, 2011), particularly the Earth, Mars, Venus, and Saturn?s
large moon Titan. The growing number of spacecraft contributing
to the exploration of Mars necessarily focuses considerable atten-
tion on the study of Mars, but the dunes on Titan have been receiv-
ing increasing attention since their discovery by the Cassini
spacecraft in 2004. The spacing of large terrestrial linear dunes
may re?ect the average depth of the atmospheric boundary layer
(Andreotti et al., 2009), which could have considerable relevance
to abundant the linear dunes on Titan, but Mars appears to have
a dearth of linear dunes. Global monitoring by the Mars Color Im-
ager (MARCI) is documenting changes across the Red Planet for
both climatological and meteorological studies, tracking move-
ment of water ice and dust clouds and providing insights into
the atmospheric dynamics related to dust lifting (Malin et al.,
2008).
Detailed images of dune patterns in Olympia Undae, the large
dune ?eld that surrounds the north pole of Mars (e.g., Tanaka
et al., 2008), is providing documentation of recent transporting
winds through the mapping of ripple orientations across individual
dunes, providing important new insights into the formation of this
largest area of dunes on Mars (Ewing et al., 2010). The margin of
the north polar sand sea is where changes in Martian sand dunes
were ?rst documented, illustrated through the disappearance of
sand dunes over three Martian years (almost 6 Earth years) (Bour-
ke et al., 2008). Steep scarps present along the margins of the north
polar chasmata (canyons), large reentrants carved through the po-
lar cap and into the underlying polar layered deposits, strongly
in?uence the direction and intensity of prevailing winds coming
off of the polar ice ?elds (Warner and Farmer, 2008). The location
and orientation of sand dunes near the north polar chasmata indi-
cates the likely source of the polar sand is from within the layered
deposits themselves (Warner and Farmer, 2008; Kocurek and Ew-
ing, 2010). The southern high latitudes do not have a large erg
comparable to the one surrounding the north polar cap, but 1190
dune ?elds have been identi?ed poleward of 50S latitude (Fenton
and Hayward, 2010), indicating that Aeolian activity is likely as
much a part of the story in southern polar regions as it is in the
north.
Fig. 1. Cross-bedded Aeolian sandstone outcrop at Cape St. Vincent on the north
rim of Victoria crater, Mars. The promontory has 12 m of vertical relief. PanCam
image taken on sol 1167 (May 7, 2007) by the Mars Exploration Rover Opportunity.
NASA PIA09694.
Fig. 2. Exposure showing unconformities in cross-bedded layered sedimentary
rocks rocks interpreted to be Aeolian in origin, in the southern part of Galle crater,
Mars (see Fig. 19 of Malin and 8 colleagues, 2010). Portion of MOC image M14-
02055, centered at 52.3S, 330.0E; scene width is 2.9 km, NASA/JPL/MSSS. Inset is
portion of HiRISE PSP_003855_1275; scene width is 125 m, NASA/JPL/U of A.
J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126 111
Author's personal copy
New data are providing important new insights into wind pat-
terns on Mars. Asymmetric arm development on barchans dunes
provides evidence for bi-modal winds on Mars, although some cau-
tion is warranted since collisions can also produce some dune
asymmetries (Bourke, 2010). Modeling of sand transport under a
bimodal wind regime, which can result from seasonally varying
wind directions, provides insight into conditions that produce
some dune shapes; the angle between the dominant wind direc-
tions, and the duration of those respective winds, have a strong
in?uence on dune shape, which can account for some unusual
dune shapes observed on Mars (Parteli et al., 2009b; Fig. 3), as well
as provide insight into temporal changes in wind patterns. Thou-
sands of individual accumulations of sand dunes have now been
mapped on Mars (Hayward et al., 2007); the widely distributed
dune locations are proving to be very useful as ?ground truth? for
constraints on atmospheric modeling of Mars, at both global and
regional scales (Hayward et al., 2009). Orbital imaging data is
now of suf?cient resolution to document the movement of both
ripples and the margins of sand dunes at locations across Mars
(e.g., Bridges et al., 2012; see Section 6.3), con?rming earlier indi-
cations of localized movement (Silvestro et al., 2010a) while also
demonstrating that widely distributed sand movement takes place
under current environmental conditions. Not only are images doc-
umenting current activity, but they are also providing new tools for
investigating past wind patterns. Distinct high-albedo markers of
prior locations of slip faces for some barchans dunes provide a
new means for mapping sand migration paths within the dunes,
and they may also prove to be useful sites for investigating the geo-
chemical implications for cementation of Aeolian sediments (Gar-
din et al., 2011). On a very local scale, Aeolian scour marks were
recently identi?ed around some Martian boulders, so that erosion
as well as deposition may now be utilized in investigating local
wind patterns (Bishop, 2011).
The capability to make direct comparisons between rover/
lander information and high resolution orbital imaging is provid-
ing new perspectives on Aeolian features. The Spirit rover carried
out both remote and in situ investigations of Aeolian bedforms at
Gusev crater (Greeley et al., 2008; Sullivan et al., 2008), including
the ?rst images documenting ripple movement on Mars, and fas-
cinating comparisons of features seen from both orbital and sur-
face perspectives. Close-up examination of wind-abraded rocks
(ventifacts Laity and Bridges, 2009) revealed that the winds
responsible for the abrasion recorded on the rocks are often from
different orientations than those responsible for nearby wind
streaks (those visible in the vicinity of the rover), but are more
consistent with the orientations of small, second-order ripples
documented on the sides of larger Aeolian bedforms in the region
examined by the rover (Thomson et al., 2008). The Phoenix Mars
Lander became the ?rst spacecraft to successfully land at a polar
region of Mars in May of 2008, and while its chemical studies
were focused on identifying water ice, the lander also carried
instruments that provided the ?rst ground measurements of the
atmosphere at polar latitudes. A ?telltale? (a hanging mass sus-
pended 1 m above the deck of the spacecraft) was imaged repeat-
edly, providing evidence of surface wind strength and direction
during the 152 days that the spacecraft operated (Holstein-Rath-
lou et al., 2010). Coordinated observations between the Phoenix
lander and the Mars Reconnaissance Orbiter provided the ?rst
?ground truth? for atmospheric monitoring of polar latitudes
(Tamppari et al., 2010).
Analog studies provided new insights into wind-related pro-
cesses and their in?uence on certain surface features. Barchan
dunes are common on both Earth and Mars (Fig. 4), so a compar-
ison of barchans planforms observed in the Namib Desert and on
Mars revealed both similarities and differences in dune dynamics
on both planets (Bourke and Goudie, 2009). The frigid conditions
in Antarctica provided a unique opportunity for ?eld investiga-
tions of sand dunes under Mars-like temperatures, which will
provide important constraints for the development of ground pe-
netrating radar instruments for eventual use on Mars (Bristow
et al., 2010a). The Mars rovers con?rmed the presence of gran-
ule-coated megaripples at both landing sites (Greeley et al.,
2004; Sullivan et al., 2005); a prolonged strong wind event at
Great Sand Dunes National Park and Preserve (in central Colo-
rado) allowed the movement rate of granule ripples to measured
and then extrapolated to current Martian conditions, suggesting
that megaripples common at the Opportunity site should require
hundreds to thousands of years to move 1 cm under wind
Fig. 3. An example of a tear-drop-shaped dune on Mars, likely formed by bimodal
winds (see Parteli et al., 2009b). Note ripple orientations around margin of dune.
Portion of HiRISE PSP_007663_1350; scene width is 535 m, NASA/JPL/U of A.
Fig. 4. Barchans and barchanoid ridges in Nili Patera, Mars. Portion of HiRISE
PSP_004339_1890 browse image, with inset showing one dune at high resolution.
NASA/JPL/U of A.
112 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126
Author's personal copy
conditions like those experienced at the Viking landers (Zimbel-
man et al., 2009). Measurement of the rates of activity for various
Aeolian actions, both depositional and erosional, will be increas-
ingly important to understanding the implications of the amaz-
ingly detailed information now being obtained by multiple
spacecraft.
4. Sediment composition on Mars
The basaltic North Polar dunes in the Olympia Undae are en-
riched with hydrated minerals (most likely gypsum, Langevin
et al., 2005; Fishbaugh et al., 2007; Horgan et al., 2009), in contrast
to the ma?c composition inferred for other dark dunes on Mars
(e.g., Rogers and Christensen, 2003; Ruff and Christensen, 2007;
Tirsch et al., 2011). Recent mapping efforts using Observatoire pour
la Mineralogie, l?Eau, les Glaces et l?Activite? (OMEGA) and Compact
Reconnaissance Imaging Spectrometer (CRISM) data show that hy-
drated minerals are concentrated in the large dark dunes of the cir-
cumpolar and adjacent dune?elds, as well as in the dust deposited
from out of the atmosphere that veneers the surface of the polar
cap (Calvin et al., 2009; Horgan et al., 2009; Mass? et al., 2010,
2012).
A spectral analysis of the composition of individual dunes in
Olympia Undae indicate that the gypsum concentration is stron-
gest at the dune crests, lower along the ?anks and weakest in
the inter-dunes (Calvin et al., 2009). At the dune?eld scale, the
strongest gypsum signatures are found in the closely spaced
dunes of Olympiae Undae, Abalos Undae and Hyperborea Undae,
located close to their proposed sediment sources (Masse et al.,
2012). Decreasing strength in spectral signature, particularly
clockwise across Olympia Undae, may be due to the increase in
dune spacing, which exposes underlying strata that do not have
a strong gypsum spectral signature. It may also be due to the
reduction in grain size or concentration of gypsum minerals with
transport distance. A smaller gypsum grain is more dif?cult to de-
tect with the OMEGA instrument (Masse et al., 2012). The analog
of terrestrial gypsum dunes provide useful insights into the
chemical stability of gypsum dunes at Olympia Undae (Szynkie-
wicz et al., 2010).
Materials beneath the polar ice cap are the proposed sediment
source for the circumpolar dune?elds (Thomas and Weitz, 1989;
Howard, 2000; Byrne and Murray, 2002; Edgett et al., 2003; Rodri-
guez et al., 2007; Tanaka et al., 2008; Warner and Farmer, 2008).
Spectral analysis of strata visible in the Basal Unit and the Upper
Layered Deposits (ULDs), exposed in troughs eroded through the
polar ice cap, have provided support for this hypothesis. Further,
the work identi?es the gypsum source in the sediment-rich layers
beneath and within the polar cap (Calvin et al., 2009; Mass? et al.,
2010, 2012). Mass? et al. (2012) suggest that the gypsum-rich sed-
iment is ablated from the icy strata at arcuate scarps in the polar
cap and from the exposed surface of Planum Boreum which under-
lies the Olympia Undae. These winds are also important in the dis-
tribution of Aeolian sediment around the pole.
Mechanisms for the formation of the polar gypsum are not well
understood and the two originally proposed hypotheses remain
plausible: (a) interaction of Ca-rich minerals with snow containing
H2SO4 derived from volcanic activity or (b) formation as an evapo-
rite during warm climatic incursions (Langevin et al., 2005). The
gypsum detected in the walls of the ULD and deposited as surface
veneers on the polar cap are proposed to form either by weathering
of dust particles, in the atmosphere prior to their deposition in the
ice cap, and/or in the ice cap after following their deposition
(Mass? et al., 2010).
Mid to low latitude dune?elds are also dominantly pyroxene
and olivine, and some have hydrated mineral signatures (e.g., Ara-
bia Terra and Meridian Planum, Tirsch et al., 2011). In general, the
hydrated dune minerals occur close to rock outcrops that are sim-
ilarly rich in hydrated minerals, suggesting a bedrock source
rather than in situ alteration. Dunes rich in sulfate are located
adjacent to the sulfate-rich interior layered deposits (ILDs) in east
and west Candor Chasma (Murchie et al., 2009a; Roach et al.,
2009). Results from the Spirit rover suggest that the chemistry
and particle shape analyses of basaltic soils at Gusev crater are
consistent with an origin through Aeolian modi?cation of im-
pact-generated sediments (McGlynn et al., 2011). Thirty percent
of dunes in the mid to low latitudes have an olivine signature
(Tirsch et al., 2011); similar to the dunes rich in hydrated miner-
als, dunes rich in olivine are located adjacent to olivine-rich ba-
salt outcrops (e.g., in the Isidis basin, Ehlmann et al., 2010;
Mustard et al., 2009). Olivine is frequently detected in small ac-
tive-looking dunes. As olivine weathers quickly, it suggests that
the dune deposits are young and have not undergone chemical
weathering. The concentration of olivine in dunes has recently
been shown to be a product of Aeolian sorting (Mangold et al.,
2011). As smaller grain sizes of olivine are dif?cult to detect in
OMEGA spectra, its absence in the majority of dune?elds might
re?ect its faster physical breakdown under Martian conditions
(Tirsch et al., 2011).
The cumulative data on dune mineralogy in the mid to low lat-
itudes is increasingly suggesting local, rather than regional sedi-
ment sources for dune?elds. The composition of dune ?elds
within craters or chasmata are similar to the composition of the
walls or ?oor of the crater or chasma (Cornwall and Titus, 2010;
Tirsch et al., 2011). Tirsch et al. (2011) determined that dark layers
in crater ?oor pits are local sources of dune?elds; they propose a
working hypothesis of a ?global? layer of dark sediment originally
deposited as a thick layer of volcanic ash in the Early to Mid Noa-
chian (4.2?3.9 Ga), rapidly buried by impact ejecta and lava. Large
craters that formed in the later Hesperian?Amazonian eras ex-
posed the volcanic ash and subsequent smaller impacts continued
release sediments for Aeolian transport. Both spectral and petro-
logic studies of basaltic sands from the Ka?u Desert in Hawaii sug-
gest that the dark dunes on Mars may be reconcilable with the
abundance of basaltic volcanism across Mars without requiring un-
ique mono-mineralic sources that otherwise might be dif?cult to
justify or explain (Tirsch et al., 2012). The dune compositions are
a distinct contrast from hydrated silicate minerals (Ehlmann
et al., 2009) and the very limited exposures of carbonate rocks
(Ehlmann et al., 2008) observed elsewhere in spectral data of Mars,
Fig. 5. Active saltation across damp sand, Bruneau Dunes State Park, central Idaho,
USA. View is looking north, centered on a reversing dune 115 m high; taken on
May 9, 2011.
J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126 113
Author's personal copy
aided in part by the typically strong albedo contrast between Mar-
tian dunes and their dusty surroundings.
5. Sediment transport
The movement and transport of sediments by the wind is a
common component to all planetary Aeolian studies (Fig. 5). We
start with several research efforts that investigated different com-
ponents of the physics involved in sediment transport by the wind
under conditions other than those on the surface of the Earth. Since
2008, many new observations of Martian wind-related features
have come out of the host of spacecraft currently active at Mars,
including analyses of extensive dune deposits in the polar regions.
Laboratory simulations have advanced our understanding of how
particulates may be set in motion on other planetary surfaces,
and several terrestrial studies are discussed that have direct rele-
vance to obtaining a better understanding of wind-surface interac-
tions on other planets.
5.1. Modeling
Several advances have been made recently in the modeling of
Aeolian sediment transport, usually with important implications
for possible sediment transport on Mars. Almeida et al. (2008a) ad-
dressed a long-standing challenge of being able to constrain parti-
cle trajectories relevant within fully developed turbulent ?ow. The
scaling laws they derived allowed these researchers to calculate
the motion of saltating grains by directly solving the turbulent
wind ?eld and its interaction with saltating particles, with the re-
sult that Mars sand grains saltate in trajectories 100 times higher
and longer than equivalent saltating grains on Earth, attaining
velocities 5?10 times higher than the equivalent grains on Earth
(Almeida et al., 2008a). The ?giant? saltation for Mars inferred by Al-
meida et al. (2008a) was challenged by Andreotti (2008), who said
that their model ignored the ability of the transported grains to ex-
pel other grains from the sand bed; with this correction, Andreotti
(2008) argued that the grain trajectories become independent of u
(the wind shear velocity) with saltation paths much smaller than
those predicted by the new model. Almeida et al. (2008b) re-
sponded to the criticism by saying that they did not adopt any
maximized ?ux value but rather determined it during the calcula-
tion, and that the model does allow transported grains to eject
other grains but rather than including a poorly constrained empir-
ical splash function, the model assumed that in the ?ux saturation
regime each grain-bed collision resulted in one ejected grain. Given
the controversy, interested readers should delve into the described
models themselves, but the ultimate size of the saltation path
length on Mars may not be quite as large as stated in the original
article.
In spite of the saltation path length issues, the Almeida model
successfully predicted both the shape and the horizontal scale of
barchan dunes imaged on the ?oor of Arkhangelsky crater on
Mars (Parteli et al., 2009a), provided the entrainment rate on
Mars is an order of magnitude higher than the corresponding va-
lue on Earth. The Parteli et al. (2009a) results are also based on a
u value of 3 m/s, which corresponds to the strongest winds in-
ferred from surface particle distributions as observed by the Mars
Exploration Rovers (Sullivan et al., 2005; Jerlomack et al., 2006).
The model also is remarkably successful in reproducing unusual
?teardrop?-shaped dunes, such as those observed in Wirtz crater
on Mars (Fig. 3), when the sand is subjected to bimodal wind con-
ditions (Parteli et al., 2009a), and the model also provides con-
straints on the likely divergence angle between the two wind
directions required to reproduce several distinctive dune shapes
recently observed on Mars (Parteli et al., 2009b; Zhu and Chen,
2010). Modeling sand transport is dependent upon how the wind
interacts with surface materials; a study of the effects of large
(>0.25 m) roughness elements, such as large rocks (common to
all landing sites on Mars), used a shear stress partitioning ap-
proach to determine that higher regional wind shear stresses
are required on Mars than on Earth for equivalent distributions
of roughness elements, primarily due to the low Martian atmo-
spheric density (Gillies et al., 2010).
Kok (2010a) showed that saltation on Mars can be maintained
by wind speeds up to an order of magnitude smaller than the wind
speed required to initiate saltation. This result could have impor-
tant implications for dune and ripple development on Mars, partic-
ularly if less extreme wind speeds could maintain saltation once it
became initiated. One way to obtain new constraints on the likely
intensity of winds blowing across Mars is to use observed dune
?elds around the planet as ?ground truth? for atmospheric model-
ing of the winds on Mars (Hayward et al., 2009). A global database
of sand dunes on Mars (Hayward et al., 2007) was used to measure
the dune centroid azimuths and slipface orientations across the
planet, for comparison with results from both global and meso-
scale climate models; the study concluded that dune centroid azi-
muth re?ects wind patterns on a regional to global scale, and
therefore are well represented by global climate models, while slip
face orientation is more easily in?uenced by local factors (like
nearby topographic relief) so that the winds responsible for the
present orientation are best understood using mesoscale models
(Hayward et al., 2009). Fenton and Michaels (2010) ran large eddy
simulations that provide a parameterization for wind gusts pro-
duced by daytime convective turbulence, which can be used with
mesoscale models to increase the daytime sand transport, some-
thing generally underestimated in current models. Finally, model-
ing of the electric ?elds present within a Martian saltation cloud
showed that electric discharges do not occur during saltation on
Mars (Kok and Renno, 2009).
Clear documentation of sand movement under current Martian
conditions provides impetus for improved modeling of sand trans-
port in the rari?ed Martian atmosphere. Calculations show that
Mars sand grains should saltate in trajectories that are 100 times
longer and higher, and reach velocities that are 5?10 times higher,
than equivalent sand grains on Earth (Almeida et al., 2008a), lead-
ing to models of dune formation and modi?cation under diverse
wind regimes (Parteli et al., 2009a, b). Similarly, a recent compre-
hensive numerical model of steady state saltation (Kok and Renno,
2009) was used to calculate that the wind speed needed to main-
tain saltation on Mars is an order of magnitude less than the wind
speed required to initiate saltation (Kok, 2010a), leading to the
possibility of a hysteresis effect that would allow for maintenance
of saltation at wind speeds much lower than previously thought
(Kok, 2010b). The on-going monitoring of documented sand
movement rates on Mars should provide a steadily growing data
set for future applications to a variety of numerical modeling
efforts.
5.2. Mars observations
Both of the Mars Exploration Rovers Spirit (Squyres et al.,
2004a) and Opportunity (Squyres et al., 2004b) have provided a
wealth of new data, including results particularly relevant to Aeo-
lian processes. Microscopic Imager close-up views obtained of
undisturbed soils along the traverse route of Spirit were used to
determine the sedimentological characteristics of >3100 individual
particles, which revealed at several locations a distinct uniform
population of medium sand that has been redistributed locally
by ongoing dynamic Aeolian processes (Cabrol et al., 2008). The de-
posit ??El Dorado?? was examined directly by Spirit, the only areally
extensive sand deposit visited by either rover; well-rounded
114 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126
Author's personal copy
medium basaltic sand here has many ripple bedforms, but local-
ized thermal vortices that swept across El Dorado locally removed
dust without perceptibly damaging the cohesionless sandy ripple
crests (Sullivan et al., 2008). The apparent contradiction between
the mobilization of dust while not signi?cantly affecting more eas-
ily entrained sand-sized particles is the result of (1) dust occurring
on the surface as fragile, low-density, sand-sized aggregates that
are easily entrained and disrupted, and (2) pervasive induration
of Martian surface materials in areas outside of active sand depos-
its (Sullivan et al., 2008). Spirit also provided the ?rst documenta-
tion on Mars of small sand ripples having migrated 2 cm in rover
images taken only two days apart (Sullivan et al., 2008). On the
other side of the planet, Opportunity performed the ?rst in situ
investigation of a dark wind streak on Mars, a streak emanating
from Victoria crater; results indicate that the Victoria wind streak
is produced by the deposition of basaltic sand blown out of the cra-
ter from dark bedforms collected below the crater rim, providing
an explanation for the serrated margin of Victoria crater through
Aeolian abrasion of relatively soft bedrock (Geissler et al., 2008).
Opportunity documented beautifully crossbedded rocks exposed
along the Victoria crater rim (Fig. 1), providing strong evidence
that the bedrock materials here were emplaced as ancient wind-
blown dunes (Squyres et al., 2009).
Views from orbit continue to reveal a host of Aeolian landforms
across the planet. The High Resolution Imaging Science Experiment
(HiRISE) obtained >9100 images of Mars during the primary sci-
ence phase of the Mars Reconnaissance Orbiter mission (between
October 2006 and December 2008), many with a resolution as good
as 25 cm/pixel, which included many sites targeted to study wind-
driven processes (McEwen et al., 2010). Repeated targeting of
many dune locations by HiRISE provided the ?rst documentation
from orbit of sand ripple mirgration on sand dunes in the Nili
Patera region of Mars, indicating a minimum of 2 m of migration
to the WSW during the ?fteen weeks between the two HiRISE
images (Silvestro et al., 2010a). Bridges et al. (2012) subsequently
documented dune and ripple movement in repeat HiRISE images
from across the planet, con?rming that under present-day condi-
tions observable changes are now being documented for numerous
Aeolian deposits on Mars (Fig. 6). As HiRISE continues to monitor
dune locations, undoubtedly more documented cases of dune
and ripple movement will become available. Orbital data also have
documented discreet sand transport pathways in the Thaumasia
region on Mars, including identi?cation of the possible source
areas for the sand (Silvestro et al., 2010c), analogous to sand path-
ways identi?ed in the southwestern United States (e.g., Zimbelman
et al., 1995; Muhs et al., 2003). The dust mantle known to cover the
broad Tharsis Montes volcanic region, as well as the Elysium and
Arabia regions (e.g., Kieffer et al., 1977; Christensen, 1986), is
now considered to consist (most likely) of sand-sized dust aggre-
gates, built up over time from ?ne airfall dust, that organizes itself
into distinctive m-scale bedforms and features now visible in HiR-
ISE images (Bridges et al., 2010). Widespread dust aggregates on
Mars raises the possibility that a Martian equivalent to parna
(Greeley and Williams, 1994) might produce ?ne-grained lithi?ed
deposits that could potentially be included in the general term
?aeolianites? (see Section 9.1).
5.3. Lab simulations
Interesting progress has been made through several laboratory
simulations that are directly relevant to planetary Aeolian pro-
cesses, but the very limited quantities of lunar soil returned to
Earth makes it impractical to conduct laboratory experiments on
actual extraterrestrial materials. Seiferlin et al. (2008) provide a
thorough review of various simulants that have been used as ana-
logs for planetary regolith materials, documenting the measured
physical properties of both the analog materials and what is known
at present about the properties of various planetary regoliths; they
conclude that many meaningful laboratory experiments can con-
tinue to be conducted on simulated regolith materials, as long as
the community remains cognizant of both the similarities and dif-
ferences between the simulants and actual regolith conditions.
Merrison et al. (2008) employed a wind tunnel chamber in which
runs using a Mars simulant to explore the effects of Aeolian trans-
portation under Martian conditions (simulating atmospheric com-
position, pressure, wind speed, temperature, and dust aerosol
suspension), resulting in valuable insight into the possible Aeolian
development and movement of dust aggregates; this facility
should prove helpful for the development, testing, and calibration
of ?ight instruments that are to be used on the Martian surface.
Detschel and Lepper (2009) exposed a Martian simulant to the so-
lar spectral irradiance expected at the Martian surface in order to
evaluate its potential effect on optically stimulated luminescence
(OSL) as a dating tool for Martian sediments. OSL has become a sig-
ni?cant tool for unraveling the complex histories of many terres-
trial dune sands, so this study has important implications for the
eventual application of OSL techniques on Martian samples, either
in situ or eventually as returned to terrestrial laboratories. The re-
sults of their work are that OSL techniques should not be compro-
mised by enhanced Martian UV radiation for use with K-feldspar,
Fig. 6. Slight changes in ripple pattern are documented in two HiRISE images taken 1366 days apart. Images are near 14.8S, 127.9E; scene width is 170 m. Left: Portion of
PSP_002860_1650. Right: Portion of ESP_020384. NASA/JPL/U of A. (After views on pages 23 and 24 of the Data Supplement for Bridges and 12 colleagues, 2012).
J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126 115
Author's personal copy
Ca-feldspar, anhydrite, or hydrous Ca and Mg sulfates, but Na-feld-
spar is capable of acquiring and retaining a signal that could in?u-
ence OSL interpretations (Detschel and Lepper, 2009). Merrison
et al. (2010) performed a unique experiment of tumbling a mixture
of silica quartz and magnetite sand for 212 days under Martian
atmospheric conditions (which they estimate would be equivalent
to about 9 years of continuous sand movement on Mars), after
which time they observed the generation of 9% (by volume) ?ne-
grained (<18 lm) hematite dust essentially independent of the
atmospheric composition used in the chamber, providing the ?rst
experimental evidence of the oxidation of magnetite to hematite
through the mechanical effects of simulated Aeolian transportation
under Martian conditions. Experimental studies such as these hold
great potential for improving our understanding of how various
materials should respond to Aeolian processes under diverse plan-
etary conditions.
5.4. Analogs
Investigations of speci?c landforms here on Earth have pro-
vided new insights into how such features may be active on other
planetary surfaces. Zimbelman et al. (2009) documented the rate of
movement of granule ripples at Great Sand Dunes National Park
and Preserve in central Colorado, from which they then calculated
the probable rate of movement of comparable granule ripples on
the surface of Mars. They concluded that a 25-cm-tall granule-
coated megaripple, similar to features traversed by the Opportu-
nity rover at Meridiani Planum, would be expected to move 1 cm
in from several hundred to a few thousand years, based on current
best estimates of the frequency of saltation events on Mars (Zimb-
elman et al., 2009). Yizhaq et al. (2009, 2012) made detailed inves-
tigations of both the generation and evolution of megaripples in
Israel, producing models that should have applicability to megarip-
ple development on other planetary surfaces. Rodriguez et al.
(2010) used wind streaks present downwind of several playas in
the desert of Argentina as analogs for wind streaks associated with
impact craters on Mars; the Argentina features show several mor-
phologic and planform similarities to the Martian wind streaks,
and the distinct chemistry of the Argentina streaks makes them
very amenable to remote documentation.
Antarctica has long been recognized as one of the best places on
Earth to simulate some of the harsh environmental conditions
anticipated to be common on Mars. Bourke et al. (2009) docu-
mented the rate of movement of sand dunes in Victoria Valley, Ant-
arctica, making use of several decades of aerial photography; the
results are not only instructive of the current Aeolian environment
in the Antarctic dry valleys, but also relevant to understanding the
interactions of mobile sand with snow and ice that seasonally
interacts with the dunes. Fieldwork on both reversing sand dunes
(Bristow et al., 2010a) and whaleback dunes (Bristow et al.,
2010b) in the dry valleys of Antarctica document the niveo-Aeolian
actions on these sand dunes, including ground penetrating radar
(GPR) surveys of the internal structure of the dunes, all of which
will be directly relevant to understanding the possible movement
of sand dunes in the polar regions of Mars. Alaska also provides
several good locations for monitoring dunes under subarctic envi-
ronmental conditions (e.g., Necsoiu et al., 2009), which should
have application to planetary conditions. As with the laboratory
work discussed above, continued analog investigations of well cho-
sen dune localities on Earth will provide important insights into
how dunes might be expected to form and move under the diverse
environmental conditions.
Dust mobilization through the action of atmospheric vortices
(?dust devils?) has received increased attention through synergistic
studies of dust devil features observed on both Earth and Mars, as
well as in the laboratory. Data from multiple spacecraft have
revealed both seasonal and location-related details of dust devils
on Mars, including observations from the MER Spirit rover (Greeley
et al., 2010), the Phoenix lander at high northern polar latitude
(Ellehoj et al., 2010), the High Resolution Stereo Camera on the
European Mars Express (Reiss et al., 2011a), and HiRISE (Choi
and Dundas (2011). Field studies of dust devil tracks on Earth (Re-
iss et al. (2010a) were complemented by new temporal data for the
development of dust devil tracks on Mars (Reiss et al., 2011b).
Innovative ?eld techniques led to in situ measurements of many
attributes of dust devils (Metzger et al., 2011), and laboratory sim-
ulations have documented the growth and evolution of dust devils
(Neakrase and Greeley, 2010a, b). Dust devils have been observed
in action so often that the statistics of their occurrence can be ex-
plored quantitatively for both Earth and Mars (Pathare et al., 2010;
Lorenz, 2011; Kurgansky, 2012). Recent work on dust lifting mech-
anisms is shedding new light on the causes of dust suspension
within the thin Martian atmosphere (Wurm et al., 2008; Spiga
and Lewis, 2010; Gheynani et al., 2011).
6. Aeolian features on Mars
Considerable recent advances have been made in identifying
and studying individual Aeolian bedforms on Mars, driven in large
part by the incredible images available from HiRISE (e.g., Fig. 7),
which has been collecting giga-pixel images of virtually every part
of Mars (McEwen et al., 2007, 2010). A summary of results ob-
tained by HiRISE includes a section about Aeolian processes and
landforms (Section 5.8 of McEwen et al., 2010), but many individ-
ual papers make use of HiRISE (as well as other spacecraft) data in
addressing issues related to bedforms developed through either
wind-related deposition or erosion. The following sections provide
a glimpse into what has been learned recently about speci?c Aeo-
lian-related features on Mars.
6.1. Dunes
Imaging capable of clearly resolving dune morphology is now
suf?ciently abundant to support global identi?cation of sand dune
localities around Mars, supporting the development (Hayward
et al., 2007) and re?nement of a Mars Global Digital Dune Database
(Hayward et al., 2009; Fenton and Hayward, 2010; Hayward,
2011). The database locates thousands of dune ?elds across the
planet, including classi?cation of various dune types, data that
has proved useful as ground truth for both Global Climate Models
Fig. 7. Detailed view of linear dunes on Mars, with albedo patterns repeated across
adjacent dunes. Portion of HiRISE ESP_016036_1370; scene width is 510 m. NASA/
JPL/U of A.
116 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126
Author's personal copy
(GCMs) and mesoscale climate models (Hayward et al., 2009). The
manual identi?cation of dunes can be augmented by automated
techniques the have been developed for detecting Martian dune
?elds, which achieved a detection rate of 95% for 78 Mars Orbiter
Camera (MOC) images obtained from diverse locations around the
planet (Bandeira et al., 2011). Regional studies of dune ?elds as
indicators of recent wind patterns on Mars (Hayward et al.,
2009; Gardin et al., 2012) that soon should be able to be expanded
to comparisons with GCM predictions (e.g., Hayward et al., 2009),
something that should soon be able to be expanded to nearly com-
plete global coverage, yet deviations between observed wind pat-
terns inferred from the dunes and the surface wind orientations
predicted by atmospheric models indicate that considerable re?ne-
ment of the modeling is still needed. What is learned from these
efforts at understanding the formation and modi?cation of dunes
on Mars should be valuable for spatial analysis of remote sensing
data and modeling the development and evolution of dune ?elds
on Earth (e.g., Diniega et al., 2010a; Bo and Zheng, 2011a,b; Huge-
nholtz et al., 2012).
Regional studies of sand dunes on Mars are providing insights
into sand mobility on the Red Planet. Climbing and falling dunes
have been identi?ed within the enormous Valles Marineris canyon
system, including dunes located on canyon walls at elevations that
are kilometers above the canyon ?oor (Chojnacki et al., 2010). Six
dune ?elds in the Thaumasia region were interpreted to indicate
the presence of distinct corridors along which the sand movement
took place (Silvestro et al., 2010c). Imaging coverage at resolutions
capable of monitoring dune planform is revealing that sand dunes
in the Arabia and Meridiani Terrae regions show signs of change at
several locations, such as inside Endeavor crater (Chojnacki et al.,
2011), in the Arabia and Meridiani Terrae regions (Silvestro et al.,
2011), in the north polar area (Hansen et al., 2011; Horgan and Bell,
2012), and indeed across the planet (Bridges et al., 2012; see Sec-
tion 6.3), while other Aeolian features on Mars are likely stable
over time scales of from thousands to millions of years (see Sec-
tion 6.4). Directional radiometry of thermal infrared imaging data
holds new potential for constraining surface slopes (Band?eld
and Edwards, 2008), a technique that could be applicable to the
largest Aeolian bedforms, such as within major dune ?elds,
information that should augment what can be derived from visual
imaging alone.
6.2. Transverse Aeolian Ridges (TARs)
Martian Aeolian features with widths and/or wavelengths on
the scale of 10 m may be either small sand dunes or large wind
ripples (Fig. 8), landforms that develop from signi?cantly different
emplacement processes; this ambiguity led to the use of the non-
genetic term ?transverse Aeolian ridge? (TAR) to describe these fea-
tures in order to preserve an open mind as to their formation
mechanism (Bourke et al., 2003; Wilson and Zimbelman, 2004).
Assessments of TARs have been conducted at both regional and
global scales, making use of MOC and THEMIS images (Balme
et al., 2008) and, more recently, HiRISE images (Zimbelman,
2010; Berman et al., 2011). The evidence indicates that both small
dunes and large ripples (megaripples) are found at the 10-m scale,
so that continued use of a non-genetic term still seems warranted
(Zimbelman, 2010; Berman et al., 2011). However, there is preli-
minary evidence that the vertical height, pro?le shape, and
height/width aspect ratio of individual bedforms may be able to
distinguish between megaripples and small dunes, and also that
large, symmetrical TARs are likely to be reversing sand dunes
(Zimbelman, 2010).
6.3. Active bedforms
Perhaps one of the most exciting recent developments in the
study of Aeolian features on Mars is the steadily growing body of
evidence that both dunes and ripples are active under current Mar-
tian conditions. While there were early indications that some of
the dunes in the polar regions of Mars showed observable changes
over a time scale of several Martian years (Bourke et al., 2008), the
consensus prevailing in the mid-2000s was that the winds on Mars
only very rarely exceeded the threshold for movement of sand,
based in large part on inferences derived from Viking lander mete-
orological measurements (e.g., Arvidson et al., 1983). The ?rst
de?nitive evidence that ripples showed measurable movement in
today?s environment came from the Spirit rover, where tens-of-
cm-scale ripples moved 2 cm within a ?ve-day period separating
navigation images (Fig. 28 of Sullivan et al., 2008). The Opportunity
rover documented Aeolian erasure of rover tracks over a period of
hundreds of Mars days, likely the result of both gradual processes
such as passage of dust devils (e.g., Fig. 9; interested readers should
check the expanded caption available for this image on the HiRISE
Fig. 8. Transverse Aeolian Ridges (TARs) cover the ?oor of Nirgal Vallis. Portion of
MOC E02-02651, centered on 27.8S, 316.7E. NASA/JPL/MSSS.
Fig. 9. A dust devil (white) casts a sinuous shadow across Amazonis Planitia.
Portion of HiRISE ESP_026051_2160; scene width is 640 m. NASA/JPL/U of A.
J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126 117
Author's personal copy
web site) and short-lived strong wind events associated with sea-
sonal dust storms (Geissler et al., 2008), consistent with earlier
observations of track erasure while Opportunity carried out the
?rst in situ investigation of a dark wind streak on Mars (Geissler
et al., 2008).
HiRISE images have revealed that, at least in several locations,
sand on Mars is moving on time scales of from weeks to years.
Widespread ripple migration was documented (averaging 1.7 m
is less than 4 Earth months) on several barchan dunes in the Nili
Patera region, the ?rst observations to provide strong constraints
on the rate of bedform movement derived from orbital data (Silv-
estro et al., 2010a). Ripple patterns on individual dunes in the
Olympia Undae dune ?eld in the north polar region of Mars were
used to map out recent transporting wind directions and their ef-
fect on dune development at the 100 m scale (Ewing et al.,
2010). Chojnacki et al. (2011) used orbital images to document
dunes in Endeavor crater (where Opportunity is now operating)
that showed both translation and erosion between 2001 and
2009 as derived from images obtained from multiple spacecraft,
providing evidence that the wind inside the crater recently ex-
ceeded the surface threshold velocity. Measurable dune advance
of between 0.4 and 1 m in one Mars year was documented in the
Arabia Terra/Meridiani region of Mars, accompanied by consistent
changes in the ripple pattern on the dunes (Silvestro et al., 2011).
High albedo features associated with the slip face orientations on
nearby barchan dunes in an equatorial dune ?eld on Mars are
interpreted to represent cemented Aeolian deposits that formed
at the base of dune avalanche faces (see Fig. 5 of Gardin et al.,
2011, and accompanying text), providing a new feature for deter-
mining the orientation of recent dune movement, much like fea-
tures observed around the barchans dunes at White Sands
National Monument in New Mexico (McKee, 1966; Kocurek et al.,
2007). Most recently, repeat HiRISE imaging of numerous moni-
tored sites representing diverse areas of Mars have documented
planet-wide sand movement of as much as a few meters per year
(Bridges et al., 2012). We are now well into the era where detection
of movement will give way to documentation of movement rates,
which will represent important constraints both for modeling
studies and for quantifying the work potential of Aeolian processes
under present Martian conditions, and may help to inform future
modeling efforts (see Section 5.1).
6.4. Inactive bedforms
At the same time that we have entered the era of documenting
current sand movement on Mars, evidence is also growing that cer-
tain Aeolian bedforms remain stable at time scales ranging from
thousands to perhaps millions of years. The Opportunity rover doc-
umented that some 20-cm-high megaripples (coated with coarse
grains) are well indurated (Sullivan et al., 2005), as was also ob-
served by Spirit in Gusev crater (Sullivan et al., 2008), suggesting
relatively long stability to maintain such induration. Extrapolation
of the rate of movement of granule-coated megaripples on Earth to
(Viking-like) Martian conditions indicated that a 25-cm-high
megaripple on Mars could take from hundreds to thousands of
Earth years to move only 1 cm (Zimbelman et al., 2009). Observa-
tions both from orbit and from the Opportunity rover indicate that
the megaripples on Meridiani Planum likely had their latest phase
of granule ripple migration between 50 and 200 ka, as evi-
denced by crater ejecta deposits from two fresh-rayed craters that
are superposed on, or superposed by, the granule-coated megarip-
ples (Golombek et al., 2010). The stability of megaripples contrasts
with sand ripple migration observed on many Martian sand dunes
(Section 6.3), but is broadly consistent with recent evidence that
some TARs exposed within the eroded Medusae Fossae Formation
(discussed in the following section) are substantially cratered
(Kerber and Head, 2011); cratered Aeolian features (Fig. 10) likely
can be interpreted to be fossilized dunes (e.g., Silvestro et al.,
2010b) or megaripples. An area ripe for future investigation is
the characterization of stabilized Aeolian features so that they
can be identi?ed con?dently using orbital data, and also contrasted
with the documented movement of wind ripples on many sand
dune surfaces.
6.5. Wind-related erosional features
The bedforms discussed above all result from Aeolian deposi-
tional processes, but erosion by wind-driven sand also produces
distinctive landforms. Obstacle marks (crescentic scours) are evi-
dent as numerous meter-scale scours around blocks of various
sizes scattered within an intracrater dune ?eld located in the Hel-
lespontus region of Mars (Bishop, 2011). When combined with
wind direction indicators on the nearby dunes, the scour marks
provide evidence that the dune ?eld has been subjected to a bimo-
dal wind regime (Bishop, 2011), demonstrating that erosional
scour marks can supplement more traditional wind direction indi-
cators associated with sand dunes. Erosion at a scale of hundreds of
meters is evident in the form of yardangs, the streamlined ridges
shaped by wind-driven sand; yardangs on Mars are particularly
well expressed in the friable Medusae Fossae Formation (MFF)
deposits located along the equator well west of the Tharsis Montes
volcanoes (Ward, 1979). HiRISE images of yardangs in the western-
most portion of the MFF deposits show clear evidence of a caprock
unit within the MFF materials; the heights of the yardangs suggest
that at least 19,000 km3 of lower member MFF materials have been
removed by the wind from just the lower member exposures
(Zimbelman and Grif?n, 2010). A survey of MOC images in the cra-
tered highlands south of the MFF deposits identi?ed dozens of iso-
lated outliers of MFF, with abundant small yardangs carved into
the deposits, suggesting that MFF initially may have covered an
area substantially larger than the current enormous extent of the
primary MFF exposures (Harrison et al., 2010). Lava ?ows embayed
into MFF exposures suggest that the erosion of the MFF yardangs
may date from the Hesperian era, so that some of the Aeolian ero-
sion represented by the yardangs could have taken place more
than 3 Ga ago (Kerber and Head, 2010). Some locations within
MFF show different yardang orientations on differing layers ex-
posed by the erosion, suggesting wind patterns may have varied
greatly with time (see Fig. 29.16 of Wells and Zimbelman, 1997).
Fig. 10. Lithi?ed dunes with many impact craters superposed on the dune surfaces,
indicating considerable time has elapsed since these dunes were last active. Portion
of HiRISE PSP_010453_1675. Inset shows context and scale, from portion of browse
image. NASA/JPL/U of A.
118 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126
Author's personal copy
6.6. Analogs
Terrestrial studies are shedding light on the formation mecha-
nisms for Aeolian features, especially for megaripples that repre-
sent one of the TAR formation alternatives. Rates of movement
were measured for 1-cm-high granule ripples at White Sands Na-
tional Monument (Jerlomack et al., 2006) and 3- and 10-cm-high
granule ripples at Great Sand Dunes National Park and Preserve
(Zimbelman et al., 2009), both of which produced comparable ?ux
rates for the granular materials, and both of which were applied to
understanding megaripples on Mars. Analytical models incorporat-
ing nonlinear dynamics are being developed and re?ned both for
normal sand ripples (Yizhaq et al., 2004) and megaripples (Yishaq
et al., 2009), constrained by ?eld documentation of the evolution of
megaripples derived from repeat stereo photogrammetry (Yizhaq
et al., 2009). Recently this work was extended to include documen-
tation of the destruction of megaripples by infrequent strong storm
winds, tracing the changes from megaripples back to normal sand
ripples (Isenberg et al., 2011). Field measurement of the pro?le
shape of sand ripples, megaripples, and sand dunes led to a method
for scaling the measured pro?les by the feature width, allowing
pro?le shapes to be compared directly for Aeolian features that
span more than three orders of magnitude in physical size (Zimb-
elman et al., in press). The Mars-like temperatures experienced in
the dry valleys of Antarctica led to ?eld studies of slipfaceless
?whaleback? dunes (Bristow et al., 2010b) and frozen reversing
dunes (Bristow et al., 2010a), both of which have application to
understanding GPR data like that which may eventually be col-
lected during rover missions to Mars. All of the new ?eld-based
data should be particularly valuable for constraining models of
long-term evolution of Aeolian systems (e.g., Diniega et al.,
2010a) and their potential application to Mars (e.g., Kok, 2010a,b).
Yardangs eroded into ignimbrite (emplaced as ?owing volcanic
ash) deposits in the high Puna region of western Argentina provide
important analog studies for understanding the MFF yardangs on
Mars (de Silva et al., 2010). Variations in the degree of welding of
the Argentina ignimbrite deposits contribute to erosional attri-
butes that are very similar to the caprock erosion-resistant tops
on some MFF yardangs. Near to the location of the Argentina yard-
ang study, are located some of the largest Aeolian megaripples yet
to be documented in the literature; these enormous ripples attain
heights up to 2.3 m, wavelengths up to 43 m, and a crest maximum
grain size up to 19 mm in size (Milana, 2009). There is continuing
debate as to whether or not these very large megaripples require
contemporaneous erosion of the bedrock in the inter-ripple
troughs (Comment: de Silva, 2010; Reply: Milana et al., 2010).
The arid, 4000-m-high Puna region holds great potential for
continuing analog studies that will be relevant to both depositional
and erosional Aeolian processes on Mars.
7. Modi?cation processes on Mars
Once the sand has been emplaced upon Martian dunes, factors
other than only Aeolian processes may come into play. Horvath
et al. (2009) described dark (low albedo) features (spots and ex-
tended streaks) visible in images of sand dunes (Fig. 11) near the
poles of Mars; they investigated origins by dry avalanche, liquid
CO2, liquid H2O, and gas-phase CO2, but no single model seemed
to adequately address the observations. The big question was
whether or not water was required to be involved in the formation
of these features, with the implied corollary that should liquid
water be directly involved, then perhaps some form of life might
take advantage of even short-lived or ephemeral appearances of
water at the surface. Further work demonstrated that the temper-
ature in the dark spots is too high for CO2 to exist in liquid form,
but the temperatures were still low enough for H2O ice to be stable
close to the surface (Kereszturi et al., 2009). This constraint led to
the development of a model for formation of a liquid interfacial
water ?lm (which can remain liquid well below the melting point
of bulk ice) through interfacial attractive pressure driven by van
der Waals forces and the curvature of the water ?lm surface
(Kereszturi et al., 2009). This model was further enhanced by con-
sideration that not only interfacial water, but also bulk brines
could form around the sand grains in the dunes under the in?uence
of solar insolation in late winter into early spring (Kereszturi et al.,
2010, 2011). The composite result is something termed ?viscous li-
quid ?lm? ?ow on and around the grains at the surface of Martian
polar sand dunes, a low-temperature rheological phenomenon that
can be active today at high polar latitudes on Mars (Mohlmann and
Kereszturi, 2010). The ?ow-like shapes of the dark features have
been well documented in many HiRISE images (e.g., Fig. 11), lead-
ing to the identi?cation of a modi?cation process on Martian polar
dunes not found on Earth: the springtime sublimation of the sea-
sonal CO2 polar caps (Hansen et al., 2011). However, other studies
of the Martian polar dunes suggest that at least some of the fea-
tures attributed to sublimation may instead result from normal
Aeolian processes (Horgan and Bell, 2012). Even the magni?cent
resolution of the HiRISE images has not yet produced conclusive
evidence of the precise mechanism(s) responsible for the defrost-
ing dark spot patterns, and the proportional roles of CO2 frost
and H2O water ?lm in the growth of dark spots remains an open
question. Laboratory experiments (discussed below) suggest addi-
tional complexities for whatever the ultimate resolution of the
defrosting dune mechanisms turns out to be.
An interesting case that is distinct from, but still possibly re-
lated to the polar dune dark spots, are numerous long gullies
(see Horgan et al., 2012, for various types of gullies on Martian
dunes) that have formed on the slip faces of sand dunes in Russell
crater (54.6S, 12.4E), which is at a high latitude but is closer to
the equator than the polar dunes whose defrosting characteristics
were discussed above. Reiss et al. (2010a) documented present day
activity within gullies on the Russell crater dunes using HiRISE
images from two Mars years; a 2-m-wide gully grew 50 m in
the ?rst year and 120 m in the second year, with all activity tak-
ing place during early spring. Channel morphology and modeled
surface temperatures led these researchers to the conclusion that
the observed changes can be best explained through transient
melting of small quantities of water ice, which triggered slurry
Fig. 11. The seasonal covering of CO2 frost is sublimating from north polar dunes,
revealing dark linear ?ow features that tend to emanate from dark spots, which
represent the ?rst signs of defrosting. Portion of HiRISE PSP_007962_2635; scene
width is 500 m. NASA/JPL/U of A.
J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126 119
Author's personal copy
?ows of sand mixed with ephemeral liquid water (Reiss et al.,
2010b). A separate study used HiRISE images and hyperspectral
data from the Compact Reconnaissance Imaging Specrometer for
Mars (CRISM; Murchie et al., 2007) to monitor the defrosting of
the Russell dunes, observing a sequence starting with dark spots
(similar to those observed during defrosting in the polar regions)
from which emanated dark linear ?ows 1?2 m wide and 50?
100 m long (Gardin et al. 2010). Spectra showed that the frost is
composed mainly of CO2 and a small amount of H2O ice, leading
to the conclusion that the dark ?ows are avalanches of a mixture
of sand, dust, and unstable CO2 gas triggered by eruption of ?ow
materials from the dark spots (Gardin et al., 2010). This role of
CO2 in present-day dune-gully activity is broadly consistent with
the study by Diniega et al. (2010b), where image monitoring over
six Martian years revealed activity within 18 gullies on 7 dune
?elds (all in the southern mid-latitudes, but not including the Rus-
sell dunes) mostly during mid-winter, although activity occurred
over a broad seasonal range. The gullies monitored by these
researchers led them to conclude that the activity occurred when
temperatures were too cold for the involvement of liquid water,
concluding that the gully modi?cationmechanism is driven by sea-
sonal CO2 frost (Diniega et al., 2010b). The volatile involved in the
dune gullies is therefore a critical component of the inferences that
can be drawn from observations of active gullies on dunes.
Laboratory studies contribute additional constraints to a discus-
sion of the volatiles that modify dune surfaces on Mars. Vedie et al.
(2008) used cold-room-based laboratory simulations to evaluate
whether dune gullies could result from groundwater seepage from
an underground aquifer, concluding that the resulting gully mor-
phology is best reproduced by linear debris ?ows resulting from
the melting of near-surface water ice intermixed with silty materi-
als. However, a subsequent laboratory and modeling study con-
cluded that gully formation in polar regions can be initiated by
?uidization of sediment over a subliming seasonal deposit of CO2
frost, leading to an essentially ?dry? mechanism for the gully mod-
i?cation (Cedillo-Flores et al., 2011). At present, it would appear
that diverse origins could be involved in high latitude dune-gully
modi?cation; these gullies deserve consideration as a unique com-
plement to on-going investigations of mid-latitude youthful gullies
(e.g., see Dickson et al., 2007; Dickson and Head, 2009; Lanza et al.,
2010; McEwen et al., 2011).
8. Titan
There has been signi?cant recent progress in studying Titan in
general (Lopes et al., 2010) and Titan?s dunes in particular, along
with assimilating lessons from Titan on Aeolian processes more
generally. The initial impression (Lorenz, 2008) was that the vast
majority of Titan?s dunes were linear in form and apparently longi-
tudinal in orientation (Fig. 12), indicating net sand transport from
west to east, and con?ned to a belt within 30 of the equator. Sub-
sequent mapping (Radebaugh et al., 2008; Lorenz and Radebaugh,
2009; Radebaugh et al., 2010) has robustly con?rmed these early
indications.
The latitudinal extent of the dunes appears reassuringly consis-
tent with climate models (e.g., Mitchell, 2008) indicating that Ti-
tan?s low latitudes should dry out (where the ?moisture? on Titan
is liquid methane; Mitchell, 2008). The single equatorial desert belt
on slowly-rotating Titan makes an instructive contrast with the
Earth?s midlatitude desert latitudes, de?ned largely by the down-
welling (dry) branches of the Hadley circulation, the location of
which is determined by the balance between solar heating and
planetary rotation. Recent studies have thoroughly documented
the latitude and elevation distributions of the sand dunes on Titan
(e.g., see Le Gall et al., 2011, 2012).
The orientation of the dunes on Titan presented a challenge, in
that GCMs appeared to indicate that low-latitude near-surface
winds should be predominantly retrograde (i.e. east to west, or
?easterlies? in meteorological parlance). This paradox, which fol-
lows from ?rst-principles considerations of overall angular
momentum balance in the atmosphere and was not particular to
any speci?c model, even caused modelers to question (Wald,
2009) whether the geomorphological interpretation of sand trans-
port direction (e.g., Radebaugh et al., 2008) was correct. Adjust-
ment of assumed topography (Tokano, 2008) failed to produce
the required prograde winds (in fact, linear dunes form in typically
bimodal wind regime ? that aspect was reproduced in the models,
but not the westerly bias). More detailed examination of the wind
statistics, however, may have resolved the issue (Tokano, 2010;
Lorenz, 2010). Speci?cally, while easterlies usually occur, for a brief
period around the equinoxes there is stronger mixing in the atmo-
sphere, leading to brief but fast westerlies at the surface. If the sal-
tation threshold is such (1 m/s) that the sand only responds to
these faster winds, the geomorphology will re?ect that wind direc-
tion rather than the prevailing easterlies.
A striking feature of the Titan dunes was their remarkable sim-
ilarity in size and spacing with large linear dunes on Earth, despite
the very different atmospheric density, gravity, etc. (Lancaster,
2006; Lorenz et al., 2006). It appears, however, that the controlling
parameter on the ultimate size and spacing of dunes is the thick-
ness of the atmospheric boundary layer, which acts to cap the
growth of dunes (Andreotti et al., 2009). The rather uniform spac-
ing of 3 km of dunes on Titan seems to ?t this hypothesis (Lorenz
Fig. 12. Example of linear dunes on Titan, as imaged by the Cassini radar system. Scene is 325 km wide, centered on 8N, 44W, taken during the Sept. 7, 2006, ?yby of Titan.
NASA PIA08738.
120 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126
Author's personal copy
et al., 2010), and would imply also that Titan?s dunes are morpho-
logically mature. The dune height, inferred from radarclinometry
(Lorenz et al., 2006; Neish et al., 2010) and photoclinometry
(Barnes et al., 2008) appears very consistent with terrestrial dunes
of the same horizontal extent (Lancaster, 2006; Radebaugh, 2009).
Titan?s dunes have prompted more general discussion of the
formation of linear dunes, with the notion that they may progres-
sively extend downwind of obstacles by particles adhering to the
growing dune (Rubin and Hesp, 2009; Radebaugh, 2009). In addi-
tion to being radar-dark, the dunes are optically dark, and they
have a characteristic near-infrared ?color? (e.g., Barnes et al.,
2008), supporting the initial suggestion (Lorenz et al., 2006) that
the sands are predominantly organic, formed by photochemical
processes in the atmosphere (Barnes, 2008; Lunine and Lorenz,
2009). Further evidence of an organic composition follows from
the recent identi?cation of the spectral signature of aromatic com-
pounds (e.g., benzene) with the dune-covered areas (Clark et al.,
2010). This makes the dune sands the largest known carbon reser-
voir on Titan (at over 100,000 km3, much more than the atmo-
sphere, and more than the lakes and seas of liquid hydrocarbons,
Lorenz et al., 2008). The principal question confronting Titan Aeo-
lian research, is how this material is converted from sub-micron
haze particles in the atmosphere into saltatable grains assumed
to be 0.25 mm across. The dunes on Titan generally appear to de-
crease in width and the amount of sand present in the interdune
regions, with increasing elevation and/or latitude, comparable to
terrestrial linear dunes in sand-rich to sand-poor environments
(Fig. 13).
9. Discussion
9.1. Signi?cant developments
Several of the topics discussed above have strong potential to
become even more important during the next few years. We antic-
ipate that growing interest in these topics within both the plane-
tary and terrestrial Aeolian communities will lead to increased
emphasis on tackling the complex issues associated with each
topic.
9.1.1. Martian aeolianites
Recent investigations of Mars have revealed that not only are
sand dunes an important part of the current Martian landscape,
but they also appear to have played a major role in the deposition
of sedimentary rocks evident across the planet. Both rover studies
(Fig. 1) and high resolution orbital imaging (Fig. 2) have docu-
mented the widely distributed occurrence of cross-bedded sedi-
mentary rocks on Mars (see Section 2), interpreted to be the
preserved record of previous dune ?elds that moved across the pla-
net. It also appears likely that silt or dust-sized materials comprise
distinctive landforms observed in the portions of the planet that
are locations of dust deposition (Bridges et al., 2010), which sug-
gests that it would not be surprising to ?nd lithi?ed versions of
such sediments in the rock record of Mars. It seems reasonable
to refer to both of these Aeolian-related sedimentary rocks as ?aeo-
lianites?; it will be important to document the occurrence of aeolia-
nite outcrops whenever and wherever they are encountered in the
rock record.
Fig. 13. Comparison of linear dunes on Titan (left) with linear dunes on Earth (right), shown at the same scale. The Belet region of Titan (top left) has dunes that are wider and
closer together, with thicker sand in the interdune area, as compared to the Fensal region of Titan (bottom left), where the dunes are 1?2 km wide and spaced further apart.
Titan radar views were taken during the Oct 28, 2007 (Belet) and April 10, 2007 (Fensal) ?ybys. Earth dune scenes are from Rub? al Khali in Oman (top right) and the Kalahari
in Namibia (bottom right); both scenes were obtained by the ASTER instrument on the Terra spacecraft. NASA PIA15225.
Fig. 14. Grooves are eroded into dunes in Herschel impact basin, Mars. Inset shows
context and scale, from portion of browse image. Portion of HiRISE
PSP_002860_1650, centered on 14.8S, 127.9E. NASA/JPL/U of A.
J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126 121
Author's personal copy
9.1.2. Sand compositional diversity
Sand-sized sediments hold great potential for sampling both
the local and regional bedrock materials that may have served as
the source for these materials (see Section 4). High spatial and
spectral resolution instruments like CRISM will allow investigators
to measure the relative contributions from bedrock outcrops
(where mineralogy favors a strong remote sensing signal) to sand
accumulations. The ubiquitous Martian dust will always present
a challenge to such efforts, but the majority of the Martian surface
should be suf?ciently dust-free to allow such investigations to pro-
gress. The curious organic-related sands of Titan (see Section 8)
clearly demonstrate that the wind can mobilize materials other
than those derived from silicate rocks alone.
9.1.3. Active versus inactive
For many years, it had been presumed that the Aeolian materi-
als on Mars would not be active under current conditions. Within
the last few years, this notion has been shown to be incorrect
(see Section 6.3). Not only HiRISE images, but also images from
the Thermal Emission Imaging System (THEMIS) visible camera,
MRO Context camera, and ESA High Resolution Stereo Camera
(HRSC) hold good potential to document dune movement across
the planet, particularly when current images can be compared to
the vast imaging record that MOC provided from 1997 to 2006
(Malin et al., 2010). Perhaps the most important aspect of monitor-
ing dune and ripple activity is the capability to establish rates of
movement, which will provide important new constraints to
atmospheric modeling efforts, which will also facilitate quantita-
tive comparisons with documented rates of sand movement here
on Earth. As long as the Cassini spacecraft continues to operate
as ?awlessly as it has to date, perhaps the radar instrument may
eventually document movement of some of the dunes on Titan,
providing additional rate information for an environment that is
very unlike that of either Earth or Mars.
9.1.4. Deposition versus erosion
High resolution images of dunes on Mars clearly show the in?u-
ence of recent winds through the pattern of ripples on their sur-
faces (e.g., Fig. 3), but the new images also show how
interpretations change with improving image resolution. MOC
images showed that at least some dunes, such as those on the ?oor
of Herschel crater, appeared to have undergone erosion since their
emplacement (Edgett and Malin , 2000). For such erosion to take
place on the dunes, it would seem that these dunes are somehow
more stabilized (if not partially lithi?ed) as compared to nearby ac-
tive dunes. HiRISE images (Fig. 14) have shown that the ??grooved
pattern?? on the Herschel dunes actually is produced by several sets
of ripples (Bridges et al., 2007), and the ripples and dunes in Her-
schel recently were documented to migrate under current condi-
tions (Cardinale et al., 2012). HiRISE images also are revealing
dramatic evidence of both the induration and subsequent erosion
of dunes on Mars (Fig. 15). Hopefully continued monitoring of sta-
bilized and eroded dunes may eventually provide some constraints
on the current rate of Aeolian abrasion of sedimentary materials on
Mars.
9.2. Gale crater
During the summer of 2011, the 150-km-diameter Gale impact
basin (4.6S, 137.2E) was chosen by NASA as the landing site for
the Mars Science Laboratory (MSL) rover Curiosity (Kerr, 2011),
achieving a remarkable August 6, 2012, landing. The central mound
of Gale crater is buried beneath a 5-km-high pile of sedimentary
rocks that have intrigued planetary scientists for many years
(e.g., Edgett and Malin, 2001; Pelkey et al., 2004; Malin et al.,
2010). When Gale became one of the ?nalists in the search for
the MSL landing site, it (along with the other candidate sites) be-
came the focus of an unprecedented remote sensing campaign,
resulting in a wealth of detailed information that has spawned
multiple studies of both the crater and the sedimentary rocks of
the central mound (Anderson and Bell, 2010; Milliken et al.,
2010; Hobbs et al., 2010; Silvestro et al., 2010b; Thomson et al.,
2011; Silvestro et al., 2013). The central mound is surrounded by
a distributed dune ?eld whose morphology indicates a complex
Aeolian history (Hobbs et al., 2010), including new observations
that Gale has both active and fossil dunes (Silvestro et al., 2010b,
2013). MSL will investigate the sedimentary rocks on the lower
portion of the mound, which have both chemical and morpholog-
ical indications that clay-bearing strata are intermixed with sul-
fate-bearing strata, rocks that are distinct from more uniformly
layered sediments on the top of the mound (Milliken et al., 2010;
Thomson et al., 2011). The uniformly layered sediments at the
top of the Gale mound show similarities to uniform layering in
nearby exposures of the lower member of MFF (Zimbelman and
Scheidt, 2012), so an extended MSL mission may eventually exam-
ine rocks that can shed light onto the perplexing history of MFF.
The instruments on MSL are designed to search for evidence of
any possible biotic activity in the early history of Mars (Kerr,
2011), but they should also provide a wealth of new data on the
sediments in Gale crater that contributed to the Aeolian history
of the crater.
Fig. 15. Weakly lithi?ed barchan dunes being erosion by the wind, superposed on a
cratered surface. Top, regional view with box showing location of detailed view.
Bottom, full-resolution view of one eroded barchan. Portion of HiRISE image
ESP_025389_1690, centered on 11.1S, 284.9E. NASA/JPL/U of A.
122 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126
Author's personal copy
10. Conclusions
Both orbiter and rover data have shown that cross-bedded sed-
imentary rocks emplaced by previous migrating dunes are an
important part of the rock record on Mars.
Improved understanding of the effects of varying wind regimes
is providing insights into how some rather unusual dune shapes
have developed.
The composition of Aeolian sediments varies regionally across
the Martian surface, and the organic-rich sands of Titan are distinct
from the wind-blown sediments commonly found on the terres-
trial planets.
Modeling efforts are helping to quantify how sediments are
moved by the wind in diverse planetary environments.
Both active and stabilized Aeolian bedforms are wide-spread
across Mars; on-going monitoring efforts should continue to im-
prove our understanding of the rates of movement.
Gullies formed on the steep faces of some high-latitude Martian
dunes indicate the potential involvement of more than one volatile
species.
The linear dunes on Titan are providing evidence that the wind
patterns on Titan may be considerably more complex than global
models would suggest.
Acknowledgements
The comments and suggestions of Simone Silvestro, Lori Fenton,
and the Editor were very helpful during revision of the manuscript.
Portions of the work reported here were supported by NASA grant
NNX08AK90G (JRZ) from the Mars Data Analysis Program.
References
Almeida, M.P., Parteli, E.J.R., Andrade, J.S., Hermann, H.J., 2008a. Giant saltation on
Mars. Proc. Nat. Acad. Sci. 105, 6222?6226. http://dx.doi.org/10.1073/
pnas.0800202105.
Almeida, M.P., Parteli, E.J.R., Andrade, J.S., Herrmann, H.J., 2008b. Reply to andreotti:
consistent saltation height measurements and physical assumptions. Proc. Nat.
Acad. Sci. 105 (39), E61.
Anderson, R.B., Bell, J.F., 2010. Geomorphology and inferred stratigraphy of the Gale
crater central mound and proposed Mars science laboratory landing site. In:
First International Conference on Mars Sedimentology and Stratigraphy. Lunar
and Planetary Institute, Houston. Abs# 6036.
Andreotti, B., 2008. Contradictory saltation height measurements and unphysical
assumptions. Proc. Nat. Acad. Sci. 105 (39), E60.
Andreotti, B., Fourriere, A., Ould-Kaddour, F., Murray, B., Claudin, P., 2009. Giant
Aeolian dune size determined by the average depth of the atmospheric
boundary layer. Nature 457 (7233), 1120?1123. http://dx.doi.org/10.1038/
nature07787.
Arvidson, R.E., Guinness, E.A., Moore, H.J., Tillman, J., Wall, S.D., 1983. Three Mars
years: Viking Lander 1 imaging observations. Science 222, 463?468.
Bagnold, R.A., 1941. The Physics of Blown Sand and Desert Dunes. Chapman and
Hall, London.
Balme, M.R., Berman, D., Bourke, M.C., Zimbelman, J.R., 2008. Transverse Aeolian
ridges (TARs) on Mars. Geomorphology 101 (4), 703?720. http://dx.doi.org/
10.1016/j.geomorph.2008.03.011.
Bandeira, L., Marques, J.S., Saraiva, J., Pina, P., 2011. Automated detection of Martian
dune ?elds. Geosci. Remote Sens. Lett. 8 (4), 626?630. http://dx.doi.org/
10.1109/LGRS.2010.2098390.
Band?eld, J.L., Edwards, C.S., 2008. Derivation of martian surface slope
characteristics from directional thermal infrared radiometry. Icarus 193 (1),
139?157.
Barnes, J.W., Brown, R.H., Soderblom, L., Sotin, C., Le Mou?lic, S., Rodriguez, S.,
Jaumann, R., Beyer, R.A., Buratti, B.J., Pitman, K., Baines, K.H., Clark, R., Nicholson,
P., 2008. Spectroscopy, morphometry, and photoclinometry of Titan?s
dune?elds from Cassini/VIMS. Icarus 195, 400?414. http://dx.doi.org/10.1016/
j.icarus.2007.12.006.
Barnes, J., 2008. Earth in deep freeze ? Saturn?s largest moon has remarkably Earth-
like mountains, lakes, and dunes ? yet their composition couldn?t be more
different. Sky Telescope 116, 26?32.
Berman, D.C., Balme, M.R., Rafkin, C.R., Zimbelman, J.R., 2011. Transverse Aeolian
ridges (TARs) on Mars II: Distributions, orientations, and ages. Icarus 213, 116?
130. http://dx.doi.org/10.1016/j.icarus.2011.02.014.
Bishop, M.A., 2011. Aeolian scours as putative signatures of wind erosion and
sediment transport direction on Mars. Geomorph 125, 569?574. http://
dx.doi.org/10.1016/j.geomorph.2010.10.029.
Bo, T.-Li., Zheng, X.-J., 2011a. The formation and evolution of Aeolian dune ?elds
under unidirectional wind. Geomorph 134, 408?416. http://dx.doi.org/10.1016/
j.geomorph.2011.07.014.
Bo, T.-Li., Zheng, X.-J., 2011b. Bulk transportation of sand particles in quantitative
simulations of dune ?eld evolution. Powder Tech. 214 (2), 243?251.
Bourke, M.C., 2010. Barchan dune asymmetry: observations from Mars and Earth.
Icarus 205, 183?197.
Bourke, M.C., Goudie, A.S., 2009. Varieties of barchans form in the Namib Desert and
on Mars. Aeol. Res. 1 (1?2), 45?54. http://dx.doi.org/10.1016/
j.aeolia.2009.05.002.
Bourke, M.C., Wilson, S.A., Zimbelman, J.R., 2003. The variability of transverse
Aeolian ridges in troughs on Mars. In: Lunar Planet. Sci., 34. Lunar and Planetary
Institute, Houston. Abs# 2090.
Bourke, M.C., Edgett, K.S., Cantor, B.A., 2008. Recent Aeolian dune change on Mars.
Geomorph 94, 247?255. http://dx.doi.org/10.1016/j.geomorph.2007.05.012.
Bourke, M.C., Ewing, R.C., Finnegan, D., McGowan, H.A., 2009. Sand dune movement
in Victoria Valley. Antarct. Geomorph. 109, 148?160. http://dx.doi.org/10.1016/
j.geomorph.2009.02.028.
Bourke, M.C., Lancaster, N., Fenton, L.K., Parteli, E.J.R., Radebaugh, J., Zimbelman, J.R.,
2010. Extraterrestrial dunes: an introduction to the special issue on planetary
dune systems. Geomorphology 121, 1?14.
Bridges, N.T., Geissler, P.E., McEwen, A.S., Thomson, B.J., Chuang, F.C., Herkenhoff,
K.E., Keszthelyi, L.P., Martinez-Alonso, S., 2007. Windy Mars: a dynamic planet
as seen by the HiRISE camera. Geophys. Res. Lett. 34, L23205. http://dx.doi.org/
10.1029/2007GL031445.
Bridges, N.T., Banks, M.E., Beyer, R.A., Chuang, F.C., Noe Dobrea, E.Z., Herkenhoff,
K.E., Keszthelyi, L.P., Fishbaugh, K.E., McEwen, A.S., Michaels, T.I., Thomson, B.J.,
Wray, J.J., 2010. Aeolian bedforms, yardangs, and indurated surfaces in the
tharsis Montes as seen by the HiRISE camera: evidence for dust aggregates.
Icarus 205 (1), 165?182.
Bridges, N.T.12 colleagues, 2012. Planet-wide sand motion on Mars. Geology 40 (1),
31?34. http://dx.doi.org/10.1130/G32373.1.
Bristow, C.S., Jol, H.M., Augustinus, P., Wallis, I., 2010a. Slipfaceless ?Whaleback?
dunes in a polar desert, Victoria Valley, Antarctica: insights from ground
penetrating radar. Geomorph 114, 361?372.
Bristow, C.S., Augustinus, P.C., Wallis, I.C., Jol, H.M., Rhodes, E.J., 2010b.
Investigation of the age and migration of reversing dunes in Antarctica
using GPR and OSL with implications for GPR on Mars. Earth Planet. Sci. Lett.
289 (1?2), 30?42.
Brown, A.J., Byrne, S., Tornabene, L.L., Roush, T., 2008. Louth crater: evolution of a
layered water ice mound. Icarus 196 (2), 433?445.
Byrne, S., Murray, B.C., 2002. North polar stratigraphy and the paleo-erg of Mars. J.
Geophys. Res. Planets 107. http://dx.doi.org/10.1029/2001JE001615.
Cabrol, N.A., Herkenhoff, K.E., Greeley, R., Grin, E.A., Schr?der, C., d?Uston, C., Weitz,
C., Yingst, R.A., Cohen, B.A., Moore, J., Knudson, A., Franklin, B., Anderson, R.C., Li,
R., 2008. Soil sedimentology at Gusev crater from Columbia memorial station to
winter haven. J. Geophys. Res. 113 (E06S05). http://dx.doi.org/10.1029/
2007JE002953.
Calvin, W.M., Roach, L.H., Seelos, F.P., Seelos, K.D., Green, R.O., Murchie, S.L.,
Mustard, J.F., 2009. Compact reconnaissance imaging spectrometer for Mars
observations of northern Martian latitudes in summer. J. Geophys. Res. Planets
114 (E00D11). http://dx.doi.org/10.1029/2009JE003348.
Cardinale, M., Silvestro, S., Vaz, D.A., Michaels, T.I., 2012. Evidences for sand motion
in the equatorial region of Mars. In: 43rd Lunar and Planetary Science
Conference. Lunar and Planetary Institute, Houston. Abstract #2452.
Cedillo-Flores, Y., Treiman, A.H., Lasue, J., Clifford, S.M., 2011. CO2 gas ?uidization in
the initiation and formation of Martian polar gullies. Geophys. Res. Lett. 38,
L21202. http://dx.doi.org/10.1029/2011GL049403.
Choi, D.S., Dundas, C.M., 2011. Measurements of Martian dust devil winds with
HiRISE. Geophys. Res. Lett. 38, L24206. http://dx.doi.org/10.1029/
2011GL049806.
Chojnacki, M., Moersch, J.E., Burr, D.M., 2010. Climbing and falling dunes in Valles
Marineris, Mars. Geophys. Res. Lett. 37, L08201. http://dx.doi.org/10.1029/
2009GL042263.
Chojnacki, M., Burr, D.M., Moersch, J.E., Michaels, T.I., 2011. Orbital observations of
contemporary dune activity in endeavor crater, Meridiani Planum, Mars. J.
Geophys. Res. 116 (E00F19). http://dx.doi.org/10.1029/2010JE003675.
Clark, R.N., Curchin, J.M., Barnes, J.W., Jaumann, R., Soderblom, L., Cruikshank, D.P.,
Brown, R.H., Rodriguez, S., Lunine, J., Stephan, K., Hoefen, T.M., Le Mouelic, S.,
Sotin, C., Baines, K.H., Buratti, B.J., Nicholson, P.D., 2010. Detection and mapping
of hydrocarbon deposits on Titan. J. Geophys. Res. 115, E10005.
Cornwall, C., Titus, T.N., 2010. Compositional analysis of 21 Martian equatorial dune
?elds and possible sand sources. LPI Contrib. 1552, 17?18.
Christensen, P.R., 1986. Regional dust deposits on Mars: physical properties, age,
and history. J. Geophys. Res. 91 (B3), 3533?3545.
Craddock, R.A., 2011. Aeolian processes on the terrestrial planets: Recent
observations and future focus. Prog. Phys. Geogr., 1-15, http://dx.doi.org/
10.1177/0309133311425399.
de Silva, S., 2010. The largest wind ripples on Earth: COMMENT. Geology e218.
http://dx.doi.org/10.1130/G30780C.1.
de Silva, S.L., Bailey, J.E., Mandt, K.E., Viramonte, J.M., 2010. Yardangs in terrestrial
ignimbrites: synergistic remote and ?eld observations on Earth with
applications to Mars. Planet. Space Sci. 58 (4), 459?471. http://dx.doi.org/
10.1016/j.pss.2009.10.002.
Detschel, M.J., Lepper, K., 2009. Optically stimulated luminescence dating properties
of Martian sediment analogue materials exposed to a simulated Martian solar
J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126 123
Author's personal copy
spectral environment. J. Lumin. 129 (4), 393?400. http://dx.doi.org/10.1016/
j.jlumin.2008.11.008.
Dickson, J.L., Head, J.W., Kreslavsky, M., 2007. Martian gullies in the southern mid-
latitudes of Mars: evidence for climate-controlled formation of young ?uvial
features base upon local and global topography. Icarus 188, 315?323. http://
dx.doi.org/10.1016/j.icarus.2006.11.020.
Dickson, J.L., Head, J.W., 2009. The formation and evolution of youthful gullies of
Mars: gullies as the late-stage phase of Mars? most recent ice age. Icarus 204,
63?86. http://dx.doi.org/10.1016/j.icarus.2009.06.018.
Diniega, S., Glasner, K., Byrne, S., 2010a. Long-time evolution of models of Aeolian
sand dune ?elds: in?uence of dune formation and collision. Geomorphology
121, 55?68. http://dx.doi.org/10.1016/j.geomorph.2009.02.010.
Diniega, S., Byrne, S., Bridges, N.T., Dundas, C.M., McEwen, A.S., 2010b. Seasonality of
present-day Martian dune-gully activity. Geology 38 (11), 1047?1050. http://
dx.doi.org/10.1130/G31287.1.
Edgett, K.S., Malin, M.C., 2000. New views of Mars Aeolian activity, materials and
surface properties: three vignettes from the Mars global surveyor Mars orbiter
Camera. J. Geophys. Res. 105 (E1), 1623?1650. http://dx.doi.org/10.1029/
1999JE001152.
Edgett, K.S., Malin, M.C., 2001. Rock stratigraphy in Gale crater, Mars. In: 32nd Lunar
and Planetary Science Conference. Lunar and Planetary Institute, Houston.
Abstract# 1005.
Edgett, K.S., Williams, R.M.E., Malin, M.C., Cantor, B.A., Thomas, P.C., 2003. Mars
landscape evolution: in?uence of stratigraphy on geomorphology in the north
polar region. Geomorphology 52 (3?4), 289?297.
Ehlmann, B.L., Mustard, J.F., Murchie, S.L., Poulet, F., Bishop, J.L., Brown, A.J., Calvin,
W.M., Clark, R.N., Marais, D.J.D., Milliken, R.E., Roach, L.H., Roush, T.L., Swayze,
G.A., Wray, J.J., 2008. Orbital identi?cation of carbonate-bearing rocks on Mars.
Science 322 (5909), 1828?1832.
Ehlmann, B.L.11 colleagues, 2009. Identi?cation of hydrated silicate minerals on
Mars using MRO-CRISM: Geologic context near Nili Fossae and implications for
aqueous alteration. JGRP 114 (E00D08).
Ehlmann, B.L., Mustard, J.F., Murchie, S.L., 2010. Geologic setting of serpentine
deposits on Mars. Geophys. Res. Lett. 37, L06201.
Ellehoj, M.D., Gunnlaugsson, H.P., Taylor, P.A., Kahanpaa, H., Bean, K.M., Cantor,
B.M., Gheynani, B.T., Drube, L., Fisher, D., Harri, A.-M., Holstein-Rathlou, C.,
Lemmon, M.T., Madsen, M.B., Malin, M.C., Polkko, J., Smith, P.H., Tamppari, L.K.,
Weng, W., Whiteway, J., 2010. Convective vortices and dust devils at the
phoenix Mars mission landing site. J. Geophys. Res. 115 (E00E16). http://
dx.doi.org/10.1029/2009JE003413.
Ewing, R., Peyret, A., Kocurek, G., Bourke, M., 2010. Dune-?eld pattern formation
and recent transporting winds in the Olympia Undae dune ?eld, north polar
region of Mars. J. Geophys. Res. (Planets) 115, E08005.
Fenton, L.K., Hayward, R.K., 2010. Southern high-latitude dune ?elds on Mars:
morphology, Aeolian activity and climate change. Geomorphology 121, 98?121.
Fenton, L.K., Michaels, T.I., 2010. Characterizing the sensitivity of daytime turbulent
activity on Mars with the MRAMS LES: early results. Mars 5, 159?171. http://
dx.doi.org/10.1555/mars.2010.0007.
Fenton, L.K., Bishop, M.A., Bourke, M.C., Bristow, C.S., Hayward, R.K., Horgan, B.H.,
Lancaster, N., Michaels, T.I., Tirsch, D., Titus, T.N., Valdez, A., 2010. Summary of
second international planetary dunes workshop: planetary analogs ?
integrating models, remote sensing, and ?eld data, Alamosa, Colorado, USA,
May 18?21, 2010. Aeolian Res. 2 (2?3), 173?178.
Fishbaugh, K.E., Poulet, F., Chevrier, V., Langevin, Y., Bibring, J.-P., 2007. On the origin
of gypsum in the Mars north polar region. J. Geophys. Res. 112, E07002. http://
dx.doi.org/10.1029/2006JE002862.
Gardin, E., Allemand, P., Quantin, C., Thollot, P., 2010. Defrosting, dark ?ow features
and dune activity on Mars: example in Russell Crater. J. Geophys. Res. 115,
E06016.
Gardin, E., Bourke, M.C., Allemand, P., Quantin, C., 2011. High albedo dune features
suggest past dune migration and possible geochemical cementation of Aeolian
sediments on Mars. Icarus 212, 590?596. http://dx.doi.org/10.1016/
j.icarus.2011.01.005.
Gardin, E., Allemand, P., Quantin, C., Silvestro, S., Delacourt, C., 2012. Dune ?elds on
Mars: recorders of climate change? Planet. Space Sci. 60 (1), 314?321. http://
dx.doi.org/10.1016/j.psss.2011.10.004.
Geissler, P.E., Johnson, J.R., Sullivan, R., Herkenhoff, K., Mittlefehldt, D., Fergason, R.,
Ming, D., Morris, R., Squyres, S., Soderblom, L., Golombek, M., 2008. First in situ
investigation of a dark wind streak on Mars. J. Geophys. Res. (Planets) 113
(E12S31). http://dx.doi.org/10.1029/2008JE003102.
Gheynani, B.T., Emami-Razavi, M., Taylor, P.A., 2011. Thermophoresis and dust
devils on the planet Mars. Phys. Rev. E 84 (5), 056305. http://dx.doi.org/
10.1103/PhysRevE.84.056305.
Gillies, J.A., Nickling, W.G., King, J., Lancaster, N., 2010. Modeling Aeolian sediment
transport thresholds on physically rough Martian surfaces: a shear stress
partitioning approach. Geomorphology 121, 15?21. http://dx.doi.org/10.1016/
j.geomorph.2009.02.016.
Golombek, M., Robinson, K., McEwen, A., Bridges, N., Ivanov, B., Tornabene, L.,
Sullivan, R., 2010. Constraints on ripple migration at Meridiani Planum from
opportunity and HiRISE observations of fresh craters. JGRP 115 (E00F08), 1?20.
Greeley, R., Iversen, J.D., 1985. Wind as a Geological Process on Earth, Mars, Venus,
and Titan. Cambridge Univ, Press, New York.
Greeley, R., Williams, S.H., 1994. Dust deposits on Mars: the ??Parna?? analog. Icarus
110 (1), 165?177.
Greeley, R.27 colleagues, 2004. Wind-related processes detected by the Spirit rover
at Gusev crater, Mars. Science 305, 810?814.
Greeley, R.15 colleagues, 2008. Columbia Hills, Mars: Aeolian features seen from the
ground and orbit. J. Geophys. Res. 113 (E06S06). http://dx.doi.org/10.1029/
2007JE002971.
Greeley, R., Waller, D.A., Cabrol, N.A., Landis, G.A., Lemmon, M.T., Neakrase, L.D.V.,
Pendleton Hoffer, M., Thompson, S.D., Whelley, P.L., 2010. Gusev crater, Mars:
observations of three dust devil seasons. J. Geophys. Res. 115 (E00F02). http://
dx.doi.org/10.1029/2010JE003608.
Grotzinger, J.P.19 colleagues, 2005. Stratigraphy and sedimentology of a dry to wet
eolian depositional system, Burns formation, Meridiani Planum, Mars. Earth
Planet. Sci. Lett. 240, 11?72. http://dx.doi.org/10.1016/j.espl.2005.09.039.
Hansen, C.J.11 colleagues, 2011. Seasonal erosion and restoration of Mars? northern
polar dunes. Science 331, 575?579.
Harrison, S.K., Balme, M.R., Hagermann, A., Murray, J.B., Muller, J.-P., 2010. Mapping
Medusae Fossae formation materials in the southern highlands of Mars. Icarus
209, 405?415. http://dx.doi.org/10.1016/j.icarus.2010.04.016.
Hayes, A.G., Grotzinger, J.P., Edgar, L.A., Squyres, S.W., Watters, W.A., Sohl-Dickstein,
J., 2011. Reconstruction of eolian bed forms and paleocurrents from cross-
bedded strata at Victoria crater, Meridiani Planum, Mars. J. Geophys. Res. 116
(E00F21). http://dx.doi.org/10.1029/2010JE003688.
Hayward, R.K., 2011. Mars global digital dune database (MGD3): north polar region
(MC-1) distribution, applications, and volume estimates. Earth Surf. Proc.
Landforms 36, 1967?1972. http://dx.doi.org/10.1002/esp.2219.
Hayward, R.K., Mullins, K.F., Fenton, L.K., Hare, T.M., Titus, T.N., Bourke, M., Colprete,
A., Christensen, P.R., 2007. Mars digital dune database. J. Geophys. Res. (Planets)
112 (E11007). http://dx.doi.org/10.1029/2007JE002943.
Hayward, R.K., Titus, T.N., Michaels, T.I., Fenton, L.K., Colaprete, A., Christensen, P.R.,
2009. Aeolian dunes as ground truth for atmospheric modeling on Mars. J.
Geophys. Res. (Planets) 114, E11012.
Hobbs, S.W., Paull, D.J., Bourke, M.C., 2010. Aeolian processes and dune morphology
in Gale crater. Icarus 210, 102?115.
Holstein-Rathlou, C.20 colleagues, 2010. Winds at the Phoenix landing site. J.
Geophys. Res. (Planets) 115 (E00E18), 1?20.
Horgan, B.H., Bell, J.F., 2012. Seasonally active slipface avalanches in the north polar
sand sea of Mars: evidence for a wind-related origin. Geophys. Res. Lett. 39,
L09201. http://dx.doi.org/10.1029/2012GL051329.
Horgan, B., Bell, J.F., Dobrea, E.N., Cloutis, E.A., Bailey, D., Craig, M., Roach, L.H.,
Mustard, J.F., 2009. The distribution of hydrated minerals in the north polar
region of Mars. J. Geophys. Res. 114 (E01005), 1?20. http://dx.doi.org/10.1029/
2008JE003187, B.,.
Horgan, B., Fenton, L., Christensen, P., 2012. Comparing active modes of mass
movement on Martian dunes. In: Third International Planetary Dunes
Workshop. Lunar and Planetary Institute, Houston. Abstract #7052.
Horvath, A., Kereszturi, A., Berczi, S., Sik, A., Pocs, T., Ganti, T., Szathmary, E., 2009.
Analysis of Dark albedo features on a southern polar dune ?eld of mars.
Astrobiology 9 (1), 90?103.
Howard, A.D., 2000. The role of eolian processes in forming surface features of the
Martian polar layered deposits. Icarus 144, 267?288.
Hugenholtz, C.H., Levin, N., Barchyn, T.E., Baddock, M.C., 2012. Remote sensing and
spatial analysis of Aeolian sand dunes: a review and outlook. Earth Sci. Rev. 111
(3?4), 319?334. http://dx.doi.org/10.1016/j.earscirev.2011.11.006.
Hynek, B.M., Phillips, R.J., 2008. The stratigraphy of Meridiani Planum, Mars, and
implications for the layered deposits? origin. Earth Planet. Sci. Lett. 274 (1?2),
214?220.
Isenberg, O., Yizhaq, H., Tsoar, H., Wenkart, R., Karneili, A., Kok, J.F., Katra, I., 2011.
Megaripple ?attening due to strong winds. Geomorph 131, 69?84. http://
dx.doi.org/10.1016/j.geomorph.2011.04.028.
Jerlomack, D.J., Mohrig, D., Grotzinger, J.P., Fike, D.A., Watters, W.A., 2006. Spatial
grain size sorting in eolian ripples and estimation of wind conditions on
planetary surfaces: application to Meridiani Planum. J. Geophys. Res. 111
(E12S02). http://dx.doi.org/10.1029/2005JE002544.
Kerber, L., Head, J.W., 2010. The age of the Medusae Fossae formation: evidence of
Hesperian emplacement from crater morphology, stratigraphy, and ancient lava
contacts. Icarus 206 (2), 669?684. http://dx.doi.org/10.1016/
j.icarus.2009.10.001.
Kerber, L., Head, J.W., 2011. A progression of induration in Medusae Fossae
formation transverse Aeolian ridges: evidence for ancient Aeolian bedforms and
extensive reworking. Earth Surf. Proc. Landforms. http://dx.doi.org/10.1002/
esp.2259.
Kerr, R.A., 2011. How an alluring geologic enigma won the Mars rover sweepstakes.
Science 333, 508?509.
Kieffer, H.H., Martin, T.Z., Peterfreund, A.R., Jakosky, B.M., Miner, E.D., Palluconi, F.D.,
1977. Thermal and albedo mapping of Mars during the Viking primary mission.
J. Geophys. Res. 82, 4249?4291.
Kereszturi, A., M?hlmann, D., Berczi, S., Ganti, T., Kuti, A., Sik, A., Horvath, A., 2009.
Recent rheologic processes on dark polar dunes of Mars: driven by interfacial
water? Icarus 201 (2), 492?503.
Kereszturi, A., Mohlmann, D., Berczi, Sz., Ganti, T., Horvath, A., Kuti, A., Sik, A.,
Szathmary, E., 2010. Indications of brine related local seepage phenomena on
the northern hemisphere of Mars. Icarus 207, 149?164. http://dx.doi.org/
10.1016/j.icarus.2009.10.012.
Kereszturi, A., Mohlmann, D., Berczi, Sz., Horvath, A., Sik, A., Szathmary, E., 2011.
Possible role of brines in the darkening and ?ow-like features on the Martian
polar dunes based on HiRISE images. Planet. Space Sci. 59 (13), 1413?1427.
http://dx.doi.org/10.1016/j.pss.2011.05.012.
Kocurek, G., Ewing, R., 2010. In: First Conference on Mars Sedimentary and
Stratigraphy. Lunar and Planetary Institute, Houston. Abs# 6068.
124 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126
Author's personal copy
Kocurek, G., Carr, M., Ewing, R., Havholm, K.G., Nagar, Y.C., Singhvi, A.K., 2007. White
sands dune ?eld, New Mexico: age, dune dynamics and recent accumulations.
Sediment. Geol. 197 (3?4), 313?331.
Kok, J.F., Renno, N.O., 2009. Electri?cation of wind-blown sand on Mars and its
implications for atmospheric chemistry. Geophys. Res. Lett. 36, L05202.
Kok, J.F., 2010a. Difference in the wind speeds required for initiation versus
continuation of sand transport on Mars: implications for dunes and dust storms.
Phys. Rev. Lett. 104, 074502.
Kok, J.F., 2010b. An improved parameterization of wind-blown sand ?ux on Mars
that includes the effect of hysteresis. Geophys. Res. Lett. 37, L12202. http://
dx.doi.org/10.1029/2010GL043646.
Kolb, E.J., Tanaka, K.L., 2001. Geologic history of the polar regions of Mars based on
Mars global surveyor data: II. Amazonian period. Icarus 154 (1), 22?39. http://
dx.doi.org/10.1006/icar.2001.6676.
Kurgansky, M.V., 2012. Statistical distribution of atmospheric dust devils. Icarus
219 (2), 556?560. http://dx.doi.org/10.1016/j.icarus.2012.04.006.
Laity, J.E., Bridges, N.T., 2009. Ventifacts on Earth and Mars: analytical, ?eld, and
laboratory studies supporting sand abrasion and windward feature
development. Geomorph 105 (3?4), 202?217. http://dx.doi.org/10.1016/
j.geomorph.2008.09.014.
Lancaster, N., 1995. Geomorphology of Desert Dunes. Routledge, London.
Lancaster, N., 2006. Linear dunes on Titan. Science 312, 702.
Lancaster, N., 2009. Dune morphology and dynamics. In: Parsons, A.J., Abrahams,
A.D. (Eds.), Geomorphology of Desert Environments. Springer, pp. 557?595.
http://dx.doi.org/10.1007/978-1-4020-5719-9_18.
Langevin, Y., Poulet, F., Bibring, J.-P., Gondet, B., 2005. Sulfates in the north polar
region of Mars detected by OMEGA/Mars express. Science 307, 1584?1586.
Lanza, N.L., Meyer, G.A., Okubo, C.H., Newsom, H.E., Wiens, R.C., 2010. Evidence for
debris ?ow gully formation initiated by shallow subsurface water on Mars.
Icarus 205 (1), 103?112. http://dx.doi.org/10.1016/j.icarus.2009.04.014.
Le Gall, A., Janssen, M.A., Wye, L.C., Hayes, A.G., Radebaugh, J., Savage, C., Zebker, H.,
Lorenz, R.D., Lunine, J.I., Kirk, R.L., Lopes, R.M., Wall, S.D., Callahan, P., Stofan,
E.R., Farr, T., 2011. Cassini SAR, radiometry, scatterometry and altimetry
observations of Titan?s dune ?elds. Icarus 213, 608?624. http://dx.doi.org/
10.1016/j.icarus.2011.03.026.
Le Gall, A., Hayes, A.G., Ewing, R., Janssen, M.A., Radebaugh, J., Savage, C., Encrenaz,
P., Cassini Radar, Team, 2012. Latitudinal and altitudinal controls of Titan?s dune
?eld morphometry. Icarus 217 (2012), 231?242. http://dx.doi.org/10.1016/
j.icarus.2011.10.024.
Lewis, K.W., Aharonson, O., Grotzinger, J.P., Kirk, R.L., McEwen, A.S., Suer, T.A., 2008.
Quasi-periodic bedding in the sedimentary rock record of Mars. Science 322,
1532?1535.
Livingstone, I., Wiggs, G.F.S., Weaverm, C.M., 2007. Geomorphology of desert sand
dunes: a review of recent progress. Earth Sci. Rev. 80, 239?257. http://
dx.doi.org/10.1016/j.earscirev.2006.09.04.
Lopes, R.M.C., Stofan, E.R., Peckyno, R., Radebaugh, J., Mitchell, K.L., Mitri, G., Wood,
C.A., Kirk, R.L., Wall, S.D., Lunine, J.I., Hayes, A., Lorenz, R., Farr, T., Wye, L., Craig,
J., Ollerenshaw, R.J., Janssen, M., LeGall, A., Paganelli, F., West, R., Stiles, B.,
Callahan, P., Anderson, Y., Valora, P., Soderblom, L., 2010. Distribution and
interplay of geologic processes on Titan from Cassini radar data. Icarus 205 (2),
540?558.
Lorenz, R.D., 2008. The changing face of Titan ? on Saturn?s hazy moon Titan,
torrential downpours of methane punctuate centuries of drought on a
landscape of sand dunes and badlands. Phys. Today 61 (8), 34?39.
Lorenz, R., 2010. Winds of change on Titan. Science 329, 519?520.
Lorenz, R., 2011. On the statistical distribution of dust devil diameters. Icarus 215,
381?390. http://dx.doi.org/10.1016/j.icarus.2011.06.005.
Lorenz, R.D., Radebaugh, J., 2009. Global pattern of Titan?s dunes: radar survey from
the Cassini prime mission. Geophys. Res. Lett. 36, L03202.
Lorenz, R.D.39 colleagues, 2006. The sand seas of Titan: Cassini RADAR observations
of longitudinal dunes. Science 312, 724?727.
Lorenz, R.D.15 colleagues, 2008. Titan?s inventory of organic surface materials.
Geophys. Res. Lett. 35, L02206.
Lorenz, R.D., Claudin, P., Andreotti, B., Radebaugh, J., Tokano, T., 2010. A 3 km
atmospheric boundary layer on Titan indicated by dune spacing and Huygens
data. Icarus 205 (2), 719?721.
Lunine, J.I., Lorenz, R.D., 2009. Rivers, lakes, dunes, and rain: crustal processes in
Titan?s methane cycle. Annu. Rev. Earth Planet. Sci. 37, 299?320.
Malin, M.C., Edgett, K.S., 2000. Sedimentary rocks of early Mars. Science 290 (5498),
1927?1937. http://dx.doi.org/10.1126/science.290.5498.1927.
Malin, M.C., Calvin, W.M., Cantor, B.A., Clancy, R.T., Haberle, R.M., James, P.B.,
Thomas, P.C., Wolff, M.J., Bell Iii, J.F., Lee, S.W., 2008. Climate, weather, and north
polar observations from the mars reconnaissance orbiter Mars color imager.
Icarus 194, 501?512.
Malin, M.C., Edgett, K.S., Cantor, B.A., Caplinger, M.A., Danielson, G.E., Jensen, E.H.,
Ravine, M.A., Sandovail, J.L., Supulver, K.D., 2010. An overview of the 1985?2006
Mars orbiter camera science investigation. Mars 5, 1?60. http://dx.doi.org/
10.1555/mars.2010.0001.
Mangold, N., Baratoux, D., Arnalds, O., Bardintzeff, J.-M., Platevoet, B., Gregoire, M.,
Pinet, P., 2011. Segregation of olivine grains in volcanic sands in Iceland and
implications for Mars. Earth Planet. Sci. Lett. 310, 233?243.
Mass?, M., Bourgeois, O., Le Mouelic, S., Verpoorter, C., Le Deit, L., Bibring, J.-P., 2010.
Martian polar and circum-polar sulfate-bearing deposits: sublimation tills
derived from the north polar cap. Icarus 209, 434?451. http://dx.doi.org/
10.1016/j.icarus.2010.04.017.
Mass?, M., Bourgeois, O., Le Mouelic, S., Verpoorter, C., Spiga, A., Le Deit, L., 2012.
Wide distribution and glacial origin of polar gypsum on Mars. Earth Planet. Sci.
Lett. 317?318, 44?55. http://dx.doi.org/10.1016/j.espl.2011.11.035.
McEwen, A.S.38 colleagues, 2007. Mars reconnaissance orbiter?s high resolution
imaging science experiment (HiRISE). J. Geophys. Res. 112 (E05S02), 1?20.
http://dx.doi.org/10.1029/2005JE002605.
McEwen, A.S.69 colleagues, 2010. The high resolution imaging science experiment
(HiRISE) during MRO?s primary science phase (PSP). Icarus 205, 2?37.
McEwen, A.S., Ojha, L., Dundas, C.M., Mattson, S.S., Byrne, S., Wray, J.J., Cull, S.C.,
Murchie, S.L., Thomas, N., Gulick, V.C., 2011. Seasonal ?ows on warm Martian
slopes. Science 333 (6043), 740?743. http://dx.doi.org/10.1126/
science.1204816.
McGlynn, I.O., Fedo, C.M., McSween, H.Y., 2011. Origin of basaltic soilds at Gusev
crater, Mars, by Aeolian modi?cation of impact-generated sediment. J. Geophys.
Res. 116 (E00F22). http://dx.doi.org/10.1029/2010JE003712.
McKee, E.D., 1966. Structures of dunes at white sands national monument, New
Mexico (and a comparison with structures of dunes from other selected areas).
Sedimentary 7 (1), 1?60.
Merrison, J.P., Bechtold, H., Gunnlaugsson, H., Jensen, A., Kinch, K., Nornberg, P.,
Rasmussen, K., 2008. An environmental simulation wind tunnel for studying
Aeolian transport on Mars. Planet. Space Sci. 56 (3?4), 426?437. http://
dx.doi.org/10.1016/j.pss.2007.11.007.
Merrison, J.P., Gunnlaugsson, H.P., Knak Jensen, S., N?rnberg, P., 2010. Mineral
alteration induced by sand transport: a source for the reddish color of Martian
dust. Icarus 205 (2), 716?718.
Metz, J.M., Grotzinger, J.P., Rubin, D.M., Lewis, K.W., Squyres, S.W., Bell, J.F., 2009.
Sulfate-rich eolian and wet interdune deposits, erebus crater, Meridiani
Planum, Mars. J. Sediment. Res. 79 (5?6), 247?264.
Metzger, S.M., Balme, M.R., Towner, M.C., Bos, B.J., Ringrose, T.J., Patel, M.R., 2011. In
situ measurements of particle load and transport in dust devils. Icarus 214,
766?772. http://dx.doi.org/10.1016/j.icarus.2011.03.013.
Milana, J.P., 2009. Largest wind ripples on Earth? Geology 37 (4), 343?346. http://
dx.doi.org/10.1130/G25382A.1.
Milana, J.P., Forman, S., Krohling, D., 2010. The largest wind ripples on Earth: REPLY.
Geology. http://dx.doi.org/10.1130/G31354Y.1, e219?e220.
Milliken, R.E., Grotzinger, J.P., Thomson, B.J., 2010. Paleoclimate of Mars as captured
by the stratigraphic record in Gale crater. Geophys. Res. Lett. 37 (4), L04201.
Mitchell, J.L., 2008. The drying of Titan?s dunes: Titan?s methane hydrology and its
impact on atmospheric circulation. J. Geophys. Res. (Planets) 113, E08015.
Mohlmann, D., Kereszturi, A., 2010. Viscous liquid ?lm ?ow on dune slopes of Mars.
Icarus 207, 654?658.
Muhs, D.R., Reynolds, R.L., Been, J., Skipp, G., 2003. Eolian sand transport pathways
in the southwestern United States: importance of the Colorado River and local
sources. Quat. Internat. 104, 3?18.
Murchie, S.20 colleagues, 2007. Compact reconnaissance imaging spectrometer for
Mars (CRISM) on Mars reconnaissance orbiter (MRO). J. Geophys. Res. 112
(E05S03). http://dx.doi.org/10.1029/2006JE0026.
Murchie, S.12 colleagues, 2009a. Evidence for the origin of layered deposits in
Candor Chasma, Mars, from mineral composition and hydrologic modeling. J.
Geophys. Res. 114 (E00D05). http://dx.doi.org/10.1029/2009JE003343.
Murchie, S.L.16 colleagues, 2009b. A synthesis of Martian aqueous mineralogy after
1 Mars year of observations from the Mars reconnaissance orbiter. J. Geophys.
Res. (Planets) 114 (E00D06).
Mustard, J.F., Ehlmann, B.L., Murchie, S.L., Poulet, F., Mangold, N., Head, J.W., Bibring,
J.-P., Roach, L.H., 2009. Composition, Morphology, and Stratigraphy of Noachian
Crust around the Isidis basin. J. Geophys. Res. 114 (E00D12). http://dx.doi.org/
10.1029/2009JE003349.
Neakrase, L.D.V., Greeley, R., 2010a. Dust devil sediment ?ux on Earth and Mars:
laboratory simulations. Icarus 206, 306?318. http://dx.doi.org/10.1016/
j.icarus.2009.08.028.
Neakrase, L.D.V., Greeley, R., 2010b. Dust devils in the laboratory: effect of surface
roughness on vortex dynamics. J. Geophys. Res. 115, E05003. http://dx.doi.org/
10.1029/2009JE003465.
Necsoiu, M., Leprince, S., Hooper, D.M., Dinwiddie, C.L., Mcginnis, R.N., Walter, G.R.,
2009. Monitoring migration rates of an active subarctic dune ?eld using optical
imagery. Remote Sens. Environ. 113, 2441?2447.
Neish, C.D., Lorenz, R.D., Kirk, R.L., Wye, L.C., 2010. Radarclinometry of the sand seas
of Africa?s Namibia and Saturn?s moon Titan. Icarus 208, 385?394.
Parteli, E.J.R., Almeida, M.P., Duran, O., Andrade, J.S., Herrmann, H.J., 2009a. Sand
transport on Mars. Comput. Phys. Commun. 180 (4), 609?611.
Parteli, E.J.R., Duran, O., Tsoar, H., Schwaemmle, V., Herrmann, H.J., 2009b.
Dune formation under bimodal winds. Proc. Nat. Acad. Sci. 106 (52),
22085?22089.
Pathare, A.V., Balme, M.R., Metzger, S.M., Spiga, A., Towner, M.C., Renno, N.O., Saca,
F., 2010. Assessing the power law hypothesis for the size-frequency distribution
of terrestrial and martian dust devils. Icarus 209, 851?853. http://dx.doi.org/
10.1016/j.icarus.2010.06.027.
Pelkey, S.M., Jakosky, B.M., Christensen, P.R., Sur?cial properties in Gale crater,
Mars, from Mars Odyssey THEMIS data. Icarus, 167(2), 244-270, http://
dx.doi.org/10.1016/j.icarus.2003.09.013.
Radebaugh, J., 2009. Titan?s sticky dunes? Nat. Geosci. 2, 608?609.
Radebaugh, J., Lorenz, R.D., Lunine, J.I., Wall, S.D., Boubin, G., Reffet, E., Kirk, R.L.,
Lopes, R.M., Stofan, E.R., Soderblom, L., Allison, M., Janssen, M., Paillou, P.,
Callahan, P., Spencer, C., Cassini Radar, Team, 2008. Dunes on Titan observed by
Cassini radar. Icarus 194 (2), 690?703.
J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126 125
Author's personal copy
Radebaugh, J., Lorenz, R., Farr, T., Paillou, P., Savage, C., Spencer, C., 2010. Linear
dunes on Titan and earth: initial remote sensing comparisons. Geomorph 121,
122?132. http://dx.doi.org/10.1016/j.geomorph.2009.02.022.
Reiss, D., Erkeling, G., Bauch, K.E., Hiesinger, H., 2010a. Evidence for present day
gully activity on the Russell crater dune ?eld, Mars. Geophys. Res. Lett. 37 (6),
L06203.
Reiss, D., Raack, J., Rossi, A.P., Di Achille, G., Heisinger, H., 2010b. First in situ analysis
of dust devil tracks on Earth and their comparison with tracks on Mars.
Geophys. Res. Lett. 37, L14203. http://dx.doi.org/10.1029/2010GL044016.
Reiss, D., Zanetti, M., Neukum, G., 2011a. Multitemporal observations o identical
active dust devils on Mars with the high resolution stereo camera (HRSC) and
Mars orbiter (MOC). Icarus 215, 358?369. http://dx.doi.org/10.1016/
j.icarus.2011.06.011.
Reiss, D., Raack, J., Hiesinger, H., 2011b. Bright dust devil tracks on Earth:
implications for their formation on Mars. Icarus 211, 917?920. http://
dx.doi.org/10.1016/j.icarus.2010.09.009.
Roach, L.H., Mustard, J.F., Murchie, S.L., Bibring, J., Forget, F., Lewis, K.W., Aharonson,
O., Vincendon, M., Bishop, J.L., 2009. Testing evidence of recent hydration state
change in sulfates on Mars. J. Geophys. Res. 114 (E00D02).
Rodriguez, J.A.P., Tanaka, K.L., Langevin, Y., Bourke, M., Kargel, J., Christensen, P.,
Sasaki, S., 2007. Recent Aeolian erosion and deposition in the north polar
plateau of Mars. Mars 3, 29?41. http://dx.doi.org/10.1555/mars.2007.0003.
Rogers, D., Christensen, P.R., 2003. Age relationship of basaltic and andesitic surface
compositions on Mars: analysis of high-resolution TES observations of the
northern hemisphere. J. Geophys. Res. 108 (E4), 5030. http://dx.doi.org/
10.1029/2002JE001913.
Rodriguez, J.A.P., Tanaka, K.L., Yamamoto, A., Berman, D.C., Zimbelman, J.R., Kargel,
J.S., Sasaki, S., Jinguo, Y., Miyamoto, H., 2010. The sedimentology and dynamics
of crater-af?liated wind streaks in western Arabia Terra, Mars and Patagonia,
Argentina. Geomorphology 121, 30?54. http://dx.doi.org/10.1016/
j.geomorph.2009.07.020.
Rubin, D.M., Hesp, P.A., 2009. Multiple origins of linear dunes on Earth and Titan.
Nat. Geosci. 2, 653?658.
Ruff, S.W., Christensen, P.R., 2007. Basaltic andesite, altered basalt, and a TES-based
search for smectite clay minerals on Mars. Geophys. Res. Lett. 43, L10204.
http://dx.doi.org/10.1029/2007GL029602.
Seiferlin, K., Ehrenfreund, P., Garry, J., Gunderson, K., H?tter, E., Kargl, G., Maturilli,
A., Merrison, J.P., 2008. Simulating Martian regolith in the laboratory. Planet.
Space Sci. 56 (15), 2009?2025.
Selvans, M.M., Plaut, J.J., Aharonson, O., Safaeinili, A., 2010. Internal structure of
Planum Boreum, from Mars advanced radar for subsurface and ionospheric
sounding data. JGRP 115, E09003.
Silvestro, S., Fenton, L.K., Vaz, D.A., Bridges, N.T., Ori, G.G., 2010a. Ripple migration
and dune activity on Mars: evidence for dynamic wind processes. Geophys. Res.
Lett. 37, L20203.
Silvestro, S., Rossi, A.P., Flahaut, J., Fenton, L.K., 2010b. Active and fossil dunes as
evidence of different Aeolian constructional events in Gale crater (Mars). In:
Lunar and Planetary Science, 41. Lunar and Planetary Institute, Houston. Abs#
1838.
Silvestro, S., Di Achille, G., Ori, G., 2010c. Dune morphology, sand transport
pathways and possible source areas in East Thaumasia region (Mars).
Geomorphology 121, 84?97. http://dx.doi.org/10.1016/
j.geomorph.2009.07.019.
Silvestro, S., Vaz, D.A., Fenton, L.K., Geissler, P.E., 2011. Active Aeolian processes on
Mars: a regional study in Arabia and Meridiani Terrae. Geophys. Res. Lett. 38,
L20201. http://dx.doi.org/10.1029/2011GL048955.
Silvestro, S., Vaz, D.A., Ewing, R.C., Rossi, A.P., Fenton, L.K., Michaels, T.I., Flahaut, J.,
Geissler, P.E., 2013. Pervasive Aeolian activity along the rover Curiosity?s
traverse in Gale crater, Mars. Geology 1. http://dx.doi.org/10.1130/G34162.1.
Spiga, A., Lewis, S.R., 2010. Martian mesoscale and microscale wind variability of
relevance for dust lifting. Mars 5, 146?158. http://dx.doi.org/10.1555/
mars.2010.0006.
Squyres, S.W.54 colleagues, 2004a. The Spirit rover?s Athena science investigations
at Gusev crater, Mars. Science 305, 794?799.
Squyres, S.W.51 colleagues, 2004b. The Opportunity rover?s Athena science
investigations at Meridiani Planum, Mars. Science 306, 1698?1703.
Squyres, S.W.33 colleagues, 2009. Exploration of Victoria crater by the Mars rover
opportunity. Science 324 (5930), 1058?1061.
Sullivan, R.17 colleagues, 2005. Aeolian processes at the Mars exploration rover
Meridiani Planum landing site. Nature 436 (7047), 58?61.
Sullivan, R.10 colleagues, 2008. Wind-driven particle mobility on Mars: insights
from Mars exploration rover observations at ??El Dorado?? and surroundings at
Gusev Crater. J. Geophys. Res. 113 (E06S07). http://dx.doi.org/10.1029/
2008JE003101.
Szynkiewicz, A., Ewing, R.C., Moore, C.H., Glamoclija, M., Bustos, D., Pratt, L.M., 2010.
Origin of terrestrial gypsum dunes?implications for Martian gypsum-rich dunes
of Olympia Undae. Geomorphology 121, 69?83. http://dx.doi.org/10.1016/
j.geomorph.2009.02.017.
Tamppari, L.K.25 colleagues, 2010. Phoenix and MRO coordinated atmospheric
measurements. J. Geophys. Res. (Planets) 115 (E00E17).
Tanaka, K.L., Rodriguez, J.A.P., Skinner, J.A., Bourke, M.C., Fortezzo, C.M., Herkenhoff,
K.E., Kolb, E.J., Okubo, C.H., 2008. North polar region of Mars: advances in
stratigraphy, structure, and erosional modi?cation. Icarus 196, 318?358.
Thomas, P.C., Weitz, C., 1989. Sand dunes and polar layered deposits on Mars. Icarus
81, 185?215.
Thomson, B.J., Bridges, N.T., Greeley, R., 2008. Rock abrasion features in the
Columbia Hills, Mars. J. Geophys. Res. 113, E08010. http://dx.doi.org/10.1029/
2007JE003018.
Thomson, B.J., Bridges, N.T., Milliken, R., Baldridge, A., Hook, S.J., Crowley, J.K.,
Marion, G.M., de Souza Filho, C.R., Brown, A.J., Weitz, C.M., 2011. Constraints on
the origin and evolution of the layered mound in Gale crater, Mars using Mars
reconnaissance orbiter data. Icarus 214, 413?432. http://dx.doi.org/10.1016/
j.icarus.2011.05.002.
Tirsch, D., Jaumann, R., Paci?ci, A., Poulet, F., 2011. Dark Aeolian sediments in
Martian craters: composition and sources. J. Geophs. Res. 116, E03002. http://
dx.doi.org/10.1029/2009JE003562.
Tirsch, D., Craddock, R.A., Platz, T., Maturilli, A., Helbert, J., Jaumann, R., 2012.
Spectral and petrologic analyses of basaltic sands in Ka?u Desert (Hawaii) ?
implications for the dark dunes on Mars. Earth Surf. Proc. Landforms. http://
dx.doi.org/10.1002/esp.2266.
Titus, T., Hayward, R., Bourke, M., Lancaster, N., Fenton, L., 2008a. Planetary Dunes
Workshop: A Record of Climate Change (Alamogordo, NM). Lunar and Planetary
Institute, Houston, TX, LPI Contribution No. 1403, pp. 84.
Titus, T.N., Lancaster, N., Hayward, R., Fenton, L., Bourke, M.C., 2008b. Priorities for
future research on planetary dunes. Eos Trans. AGU 89 (45), 447?448.
Titus, T., Hayward, R., Bourke, M., Lancaster, N., Fenton, L., 2010. Second
International Planetary Dunes Workshop: Planetary Analogs ? Integrating
Models, Remote Sensing, and Field Data (Alamosa, CO). Lunar and Planetary
Institute, Houston, TX, LPI Contribution No. 1552, pp. 77.
Tokano, T., 2008. Dune-forming winds on Titan and the in?uence of topography.
Icarus 194 (1), 243?262.
Tokano, T., 2010. Relevance of fast westerlies at equinox for the eastward
elongation of Titan?s dunes. Aeol. Res. 1, 113?127.
Vedie, E., Costard, F., Font, M., Lagarde, J.L., 2008. Laboratory simulations of Martian
gullies on sand dunes. Geophys. Res. Lett. 35, L21501.
Wald, C., 2009. In dune map, Titan?s winds seem to blow backward. Science 323,
1418.
Ward, A.W., 1979. Yardangs on Mars: evidence of recent wind erosion. J. Geophys.
Res. 84, 8147?8166.
Warner, N.H., Farmer, J.D., 2008. Importance of Aeolian processes in the origin of the
north polar chasmata, Mars. Icarus 196 (2), 368?384.
Wells, G.L., Zimbelman, J.R., 1997. Extraterrestrial arid surface processes. In:
Thomas, D.S.G. (Ed.), Arid Zone Geomorphology: Process, Form and Change in
Drylands, second ed. John Wiley & Sons, New York, pp. 659?690.
Whitney, M.I., 1978. The role of vorticity in developing lineation by wind erosion.
Geol. Soc. Am. Bull. 89 (1), 1?18.
Wilson, S.A., Zimbelman, J.R., 2004. The latitude-dependent nature and physical
characteristics of transverse Aeolian ridges on Mars. J. Geophys. Res. 109,
E10003. http://dx.doi.org/10.1029/2004JE002247.
Wurm, G., Teiser, J., Reiss, D., 2008. Greenhouse and thermophoretic effects in dust
layers: the missing link for lifting of dust on Mars. Geophys. Res. Lett. 35,
L10201. http://dx.doi.org/10.1029/2008GL033799.
Yizhaq, H., Balmforth, N.J., Provenzale, A., 2004. Blown by wind: nonlinear dynamics
of Aeolian sand ripples. Physics 195, 207?228. http://dx.doi.org/10.1016/
j.physd.2004.03.015.
Yizhaq, H., Isenberg, O., Wenkart, R., Tsoar, H., Karnielia, A., 2009. Morphology and
dynamics of Aeolian megaripples in Nahal Kasay, Southern Israel. Isr. J. Earth
Sci. 57, 149?165.
Yizhaq, H., Katra, I., Kok, J.F., Isenberg, O., 2012. Transverse instability of
megaripples. Geology 40 (5), 459?462. http://dx.doi.org/10.1130/G32995.1.
Zhu, J., Chen, C.-X., 2010. Model for formation of dunes at the north Martian pole.
Chin. Phys. Lett. 27.
Zimbelman, J.R., 2010. Transverse Aeolian ridges on Mars: ?rst results from HiRISE
images. Geomorph 121, 22?29. http://dx.doi.org/10.1016/
j.geomorph.2009.05.012.
Zimbelman, J.R., Grif?n, L.J., 2010. HiRISE images of yardangs and sinuous ridges in
the lower member of the Medusae Fossae formation, Mars. Icarus 205, 198?210.
http://dx.doi.org/10.1016/j.icarus.2009.04.003.
Zimbelman, J.R., Scheidt, S.P., 2012. Crater retention ages indicate a Hesperian age for
western and central portions of the Medusae Fossae formation, Mars. In: Lunar
and Planetary Science. Lunar and Planetary Institute, Houston. Abstract# 2052.
Zimbelman, J.R., Williams, S.H., Tchakerian, V.P., 1995. Sand transport paths in the
Mojave Desert, Southwestern United States. In: Tchakerian, V. (Ed.), Desert
Aeolian Processes. Chapman and Hall, New York, pp. 101?129.
Zimbelman, J.R., Irwin, R.P., Williams, S.H., Bunch, F., Valdez, A., Stevens, S., 2009.
The rate of granule ripple movement on Earth and Mars. Icarus 203, 71?76.
http://dx.doi.org/10.1016/j.icarus.2009.03.033.
Zimbelman, J.R., Williams, S.H., Johnston, A.K., 2012. Cross-sectional pro?les of sand
ripples, megaripples, and dunes: a method for discriminating between
formational mechanisms. Earth Surf. Proc. Landforms 37, 1120-1125.
126 J.R. Zimbelman et al. / Aeolian Research 11 (2013) 109?126