GEOGRAPHICAL DEVELOPMENT OF THE AMERICAS 133 



fornia. The upheavals late in the Pleistocene, or at its close, 

 were far greater than on the Atlantic side, 4000 feet in south- 

 eastern Alaska, 200 feet on the coast of Oregon and rising again 

 to 3000 feet in southern California ; all the western mountain 

 ranges and plateaus were increased in height by these move- 

 ments. The volcanoes continued to be very active, as may be 

 seen from the lava-sheets and streams in Alaska, all the Pacific 

 states, Arizona and New Mexico. 



South America. — No such vast ice-sheets were formed in 

 the southern hemisphere as in the northern. Patagonia was 

 the only part of South America to be extensively covered with 

 ice and there traces of three glaciations have been observed, 

 of which the first was the greatest and reached to the Atlantic 

 coast, and there were great ice-masses on the coast of southern 

 Chili. Mountain glaciers existed throughout the length of the 

 Andes across the Equator to 11° N. lat., the elevation increas- 

 ing northward to the tropics. The surface of the great Argentine 

 plain of the Pampas between 30° and 40° S. lat. is covered 

 with a vast mantle, largely of wind-accumulated dust, the Pam- 

 pean, which is the sepulchre of an astonishing number of great 

 and strange beasts. The Pampean formation corresponds 

 in a general way to the Sheridan or Equus Beds of North 

 America, but involves a much greater lapse of time, beginning 

 earlier, possibly in the late PUocene, and apparently lasting 

 through the entire Pleistocene. While largely of seoUan origin, 

 the Pampean seems to be in part made of delta deposits 

 laid down by rivers. One striking difference between the 

 Pampean, on the one hand, and the Sheridan and the loess of 

 the Mississippi Valley and of Europe, on the other, is that the 

 former is in many places much more consoUdated and stony, 

 which gives it a false appearance of antiquity. Another and 

 very rich source of Pleistocene mammals is found in the hme- 

 stone caves of eastern Brazil, which have yielded an incredible 

 quantity of such material, but not in such a remarkably per- 

 fect state of preservation as the skeletons of the Pampean. 



