PRESIDENTIAL ADDRESS. LXXXV 



The large discoidal Orhitolites, once so common in the warm 

 Tertiary seas of the Paris basin, are abundant in the Miocene 

 greensands of the Victorian Mallee. It has now retreated to 

 lower latitudes, being found in Shark's Bay, Western Aus- 

 tralia, at latitude 26°, and off the Great Barrier Reef, Queens- 

 land, at about the same parallel. 



The Kalimnan (L. Pliocene) climate (warm temperate to 

 cold). — The Limopsis heaumariensis of the Lower Pliocene 

 of Beaumaris, in Victoria, is closely allied to a Japanese 

 species now found in lower latitudes. Tlie presence of 

 Saxicava and abundant Natica and Tellina indicate a con- 

 siderable cooling down of the climate in this period. 



Post-kalimnan (Late Pliocene and Pleistocene) climate 

 (temperate to cold). — The brackish foraminifera of the Mallee 

 indicate a further cooling down from temperate to cold con- 

 ditions, "i 



This pal^eontological evidence implies a chilling of the waters 

 in South Australian seas to the extent of about 6° to 7" F., and 

 all this has taken place since Pleistocene time. In view of the 

 fact that the Area trapezia beds are about 15 feet above sea-level 

 in New South Wales, it is suggested that perhaps these raised 

 beaches may have formed during an interglacial epoch in late 

 Cainozoic time. The melting off of a thickness of about 600 feet 

 of ice in Antarctica would suffice to raise sea-level around Australia 

 by about the above amount of 15 feet. 



It is quite beyond the scope of the present inquiry to seek for 

 all possible causes of these vicissitudes of climate, but the question 

 as to whether variation in the geographical distribution in land 

 and water will explain all the phenomena may be very briefly 

 discussed. 



In Permo-Carboniferous time, Chamberlain and Salisbury state^ 

 that a census a few years ago gave the known animal species of the 

 carboniferous as 10,000, while those of the Permian were only 300, 



* Mr. Walter Howcbin has called my attention to the following interesting facts in regard 

 to the Post-Tertiary climate of Australia : — At the graving dock at Glanville. near Adelaide, and 

 also at a drainage tank at Dry Creek, not far from the same city, are two well marked horizons 

 carrying a geologically recent marine fauna. The lower horizon is separated from the Lower 

 Pliocene marine series by alluvial beds, without any evidence of marine conditions, 300 feet in 

 thickness. Of the two Post-Pliocene marine horizons the [ower at its upper limit is now about 

 25j feet below high water at Glanville, and 6J feet below high water at Dry Creek. It is 

 separated from the upper, and evidently recent, marine horizon bya thickness of from 16-25 feet 

 of freshwater beds, chiefly clays and sands. The upper marine deposit, a few feet in thickness, 

 contains remains of a marine fauna identical with that in the neighboring seas, but the lower 

 marine deposit, while all its species are recent, contains some forms not found now on the coasts 

 of South Australia. For example, both at Dry Creek and at Glanville it contains an abundance 

 of Area trapezia and "the large \i&rm-se&' iorajmniiei, Orhitolites comjjlanata.'' The latter 

 species has now deserted South Australian waters, and has moved up to about 26° on the west 

 coast of Western Australia, and up to about the same parallel of latitude on the east coast. 

 As Area trapezia is known to live at present in Australian wpters as far south as Western Port, 

 Victoria, its evidence of former warmer seas is not as strong as that of the above foraminifer. 



2 Geoioav, Straticraphical, Vol. IT., p. 642. Considerable additions have of late been made 

 to the number of Permian species, but nevertheless the fact is still broadly as above stated. 



