CLIMATES OF GEOLOGIC TIME. 



267 



ment of the entire organic world of the Pleistocene lands, other than that of the tropics. 

 More than once man and his organic surroundings have been forced to wander into new 

 regions; the life of cool to cold climates has dispossessed that of milder temperatures, and 

 with each moderation of the climate the hardier floras and faunas have advanced with the 

 retreating glaciers, or become stranded and isolated in the mountains. As the organic 

 world is dependent upon sunlight, temperature, and moisture, it is not difficult to see why 

 these same factors are essential to man and his civilization. 



PERMIC GLACIATION. 



Hardly had the Pleistocene glacial climate been proven when geologists began to point 

 out the possibility of earlier ones. An enthusiastic Scotch writer. Sir Andrew Ramsay, 

 in 1855 described certain late Paleozoic conglomerates of middle England, which he said 

 were of glacial origin, but his evidence, though never completely gainsaid, has not been 

 generally accepted. In the following year, an Enghshman, Dr. W. T. Blanford, said that 



Fig. 88.— Paleogeography and Glaciation of Early Permic Times. 



the Talchir conglomerates occurring in central and southern India were of glacial origm, 

 and since then the evidence for a Permic glacial period has been steadily accumulating. 

 The land of ancient tills (tiUites of geologists) is Africa, and here in 1870 Sutherland pointed 

 out that the conglomerates of the Karoo formation were of glacial origin, and, further, 

 that they rest on a land surface which has been grooved, scratched, and polished by the 

 movement of glaciers. Australia also has Permic glacial deposits. It is only very recently 

 that the evidence found in many places in the southern hemisphere has become widely 

 known, but so convincing is this testimony that all geologists are now ready to accept the 

 conclusion that a glacial chmate was as widespread in Permic time as was that of the 



