22 THE PROBLEM OF ANTIQUITY OF MAN IN AUSTRALIA 
David, 1924 Lewis, 1933, 1934 Edwards, 1941 
Giinz Glaciation . ? Malanna glacia~ ?>Submerged 
tion in part. basalt-filled val- 
leys. 
Pre-Glacial'. . . Gravels at 50-100 
ft. Helicidae 
sandstone at 100 
ft. Claypan de- 
posits underlying 
Mowbray 
Swamp. 
Contour maps prepared by Noetling (1909) from soundings 
recorded on Admiralty charts show that a lowering of sea level 
by 25 fathoms (150 ft.) Would almost connect Tasmania and 
Australia by land, and a fall of 30 fathoms (180 ft.) would com- 
plete the land-bridge.’ Lewis (1934) correlates the greatest fall 
in sea level that he found in Tasmania, about 150 ft., with the 
Malanna glacial phase, and Edwards (1941) with the Yolande. 
If either of these opinions is correct, and there have been no 
appreciable tectonic movements, island and mainland have been 
separated by sea since the second or third Pleistocene glacial 
epoch, a period antedating the migration of Homo sapiens into 
Hurope. 
The fauna of Tasmania and adjacent islands in Bass Strait 
differs from that of the Australian mainland in several respects, 
suggesting that the two regions have been isolated from each other 
long enough for evolutionary changes to have taken place. The 
Tasmanian region is small and its topography and climate 
resemble those of the adjacent mainland, particularly Gippsland. 
Differences in fauna may be illustrated by birds and mammals. 
Tasmania has about 200 species of birds, most of them in common 
with Australia, of which about one-fourth are passerine, a ratio 
of 1 to 3 in contrast to a ratio of 1 to 1 on the mainland. Of nine 
good species confined to the Tasmanian region, two are restricted 
to Tasmania proper and seven are also found on adjacent islands. 
In addition, many well-defined subspecies are peculiar to this 
region. Tasmania has 32 species of land mammals; two mono- 
tremes (Platypus and Echidna), 20 marsupials, and 10 placentals 
(rats and bats). The Echidna is a subspecies confined to Tasmania 
and adjacent islands. Twelve of the marsupials are found also 
in Australia, but eight good species and three subspecies are 
restricted to the Tasmanian region; of these, four species are 
found only in Tasmania, and four species and three subspecies 
also inhabit adjacent islands. Macropus billardieri, one of the 
7. For supplementary soundings see Dannevig (1910). 
