PALEOZOIC TIME — CARBONIC. 737 



TOPOGRAPHIC CHANGES IN THE INDIAN OCEAN; GONDWANA LAND. 



The close relations in species of India and South Africa during the 

 Permian and Triassic periods has led to the belief that the two were then 

 connected by a belt of land, and Suess has named the emerged area 

 ''Gondwana Land," from the name of the series, including the Permian and 

 Triassic beds, in India. R. D. Oldham remarks (1894) that " the plants of 

 the India and Africa Coal-measures are absolutely identical ; and among the 

 few animals which have been found in the India deposits, one is indistinguish- 

 able from South African species, and another is closely allied; and both 

 faunas are characterized by the remarkable group of Reptiles comprising the 

 Dicynodon and other allied forms." In a map by Neumayr (1885), and its 

 reproduction with some modifications by Oldham, the connecting belt of land 

 extends from India south-southwest ward over the Indian Ocean along the 

 range of islands to Madagascar and southern Africa. Among the groups of 

 islands there is the line of the Maldives and the Chagos group ; then, farther 

 west, the Seychelles group heading a line reaching to Newfoundland, and 

 also, to the eastward, a line extending to the Mascarene Islands east of 

 Madagascar. The emerged land makes an off-shore belt for eastern Africa, 

 somewhat like the island range off the shores of eastern Asia, but more 

 continuous. But great depths now exist between the groups. 



The identity in Permian coal-plant vegetation is as great with Australia 

 as with South Africa. The emerged land, on this evidence, has been supposed 

 by some writers to have covered much of the Indian Ocean. But it is most 

 probable that whatever connection existed for the migration of the plants, it 

 "Was produced by the spreading of the Antarctic continent northward to a line 

 between the parallels of 35° and 45° S. The absence of the Karoo Reptiles 

 from Australia appears to indicate that the connection Avith South Africa was 

 not complete ; but it may be that the climate of the northern part of Ant- 

 arctica was not warm enough to favor their migration, while suflficient for 

 that of the plants. Australia also was enlarged ; for Triassic fossil plants 

 from iSTew Zealand and New Caledonia show that these islands, as well as 

 New Guinea, were then included within its limits. 



The idea that Antarctic land of so great extent became emerged in the 

 Permian era, or about that time, suggests a reason for the existence of evi- 

 dences of glacial phenomena in the Permian of South Africa, India, and 

 Australia. For such a geographical change would certainly have caused a 

 general refrigeration of southern climates ; and if sufficient to produce icy 

 winters and glaciers about high summits, all the observed facts would have 

 their explanation. 



Dana's manual — 47 



