National Zoological Park: Smithsonian Institution? Washington , D.C. 20008 
Letter from the Desk of David Challinor
 
October 1991
 
For two weeks this past month I led a smithsonian Associates 
cruise from Belgium to Barcelona. While preparing my lectures 
about the geological history of the Mediterranean, I learned some 
surprising information about this almost land-locked sea and the 
strange mammals and birds that lived until relatively recently 
(10,000 years ago) on such islands as Malta and Sardinia. I 
would like to share with you some of this knowledge. 
In the Miocene epoch, about 20 million years ago, a large sea 
stretched from Gibralter all the way to what is now Irani we call 
it the Tethys Ocean. Plate movement closed the eastern end of 
this sea so that about 15 million years ago the rough boundaries 
of the present Mediterranean were formed. The west end had two 
entrances to the Atlantic, one in southern Spain and one in 
Morocco. 
About 5-1/2 million years ago, an extraordinary event occurred. 
The Atlantic Ocean access to the Mediterranean was severed or 
severely curtailed, either by tectonic movement or by a lowering 
of the world's oceans caused by expanding ice caps in Greenland 
and the Antarctic. Without adequate inflow, the Mediterranean 
dried up. The Rhone, Nile, and other smaller rivers were unable 
to offset the rapid evaporation, and huge canons were cut at the 
mouths of these two major rivers as they cascaded down to the 
deep floor of the former sea. 
We can only speculate on how long it took for the Mediterranean 
to dry UPi estimates vary from as little as 1,000 years to as 
much as 500,000. What resulted, however, was a series of deep?
lying salt pans, which rapidly evaporated whatever water (fresh 
or salt) reached them. 
Cores taken below the top 500' of the current Mediterranean sea 
bottom by the research drilling ship Glomar Challenger during the 
1970's have revealed a bed of evaporites (the salts that are left 
when sea water evaporates) about 3000' thick. This is an 
incredible amount of salts, and its presence is difficult to 
explain. 
1889-1989 
" ...for the advancement of science and 
the education and recreation of the people. " 
Letter From the Desk of ...	 October 1991 
Page 2 
To give you an idea of how much salt water had to evaporate to 
produce a salt bed this thick, it would be necessary to evaporate 
a volume of sea water equal to the upper 350 feet (110 m) of the 
World Ocean. The lowering of the Mediterranean sea level started 
with the closure of one of two narrow passageways in northern 
Morocco. Dick Benson, a smithsonian scientist working on the 
paleobiology of Morocco, estimates that the one remaining 
passageway could have furnished enough salt water in less than 
30,000 years to form the thick salt deposits found by the Glomar 
challenger. Other scientists think the Mediterranean must have 
emptied and refilled 40 times -- an unlikely scenario. 
While the Mediterranean was virtually empty, African mammals 
migrated north, and hippos and elephants, for example, colonized 
much of the high lying area. When the Mediterranean filled again 
some half million years later, the high elevations became islands 
and the elephants and hippos were isolated. Malta, for example, 
had 3 species of pygmy elephants, the tallest standing only 7' at 
the shoulder. Fossils of pygmy elephants have been found on many 
other Mediterranean islands. Clearly, as their habitat shrank 
with the rising waters, these elephants had to become smaller to 
survive. Almost all of these island animals disappeared about 
the time man arrived; today only their bones survive to tell us 
what they looked like. 
The elephants at the National Zoo are faring considerably better 
than their ancient island relatives. You may remember my April, 
1990 letter about Tony, the female Indian elephant from the now 
defunct Scranton, Pennsylvania zoo. She was the last animal to 
be placed, and when she arrived in Washington, D.C. she had not 
seen another elephant for 17 years. As a result, she was 
terribly shy and frightened of the three other elephants (one 
African and two Indian) living together in the next paddock. I 
am happy to report that under the patient training of our 
elephant keepers, Tony has now joined the others in the elephant 
yard. 
The mammoths and mastodons may have been extirpated by human 
hunters as the pygmy elephants of Malta and Sardinia may also 
have been. All these elephants existed with people, but the 
exact cause of their extinction may never precisely be known. 
Today, however, we can see the detrimental effect humans are 
having on the two remaining elephant species, and thus we have a 
global responsibility to stave off their demise. Zoo breeding is 
one way to accomplish this goal. Shanti, our large female Indian 
elephant, is now on breeding loan to the Schenectady Zoo. If she 
successfully conceives, do not hold your breath awaiting the 
arrival of the baby, because elephants have a gestation period of 
over 600 days!