ANCIENT CLIMATES 8i 



limit of Pleistocenic glaciation in North America was at latitude 

 37° 30' in the Mississippi valley, while in Europe it did not extend 

 below about 53°, though the Alps and other great mountain ranges 

 were heavily glaciated. The high mountain areas of /\sia (Leb- 

 anon, the Caucasus, the Himalayas and the mountains of Man- 

 churia) were heavily glaciated, these glaciers reaching down to 

 4,500 feet A. T. in latitude 26° in Bengal, and to 2,000 or 3,000 

 feet in the western Himalayas. (Coleman-19 rj.^^.) The Atlas 

 Mountains of Africa and the lofty peaks under the equator all show 

 an advance of the glaciers of several thousand feet lower than at 

 present. A similar extent of glaciation of the southern hemisphere 

 would not have reached any of the continents, except the southern 

 end of South America and perhaps New Zealand. The greater 

 expanse of ocean, however, with its more moderate climate, would 

 favor a less extent of the Atlantic ice; and it may be questioned if 

 the ice sheet which is known to have been much more extensive 

 over the Antarctic continent extended much beyond its border. 

 Patagonia, it is true, was widely glaciated south of latitude 37°, 

 the ice reaching the sea. This may have been purely local, however. 

 In the Andes, further north, even within the tropics, are old mo- 

 raines, showing the extent of these glaciers 800 to 900 meters below 

 their present position. 



The now incontrovertible evidence pointing to glacial periods at 

 various times during the geologic history of the earth from pre- 

 Cambric time on, indicates not only repeated periods of greater cold 

 in the earth's atmosphere, explainable by the reduction in the 

 amount of COo, but also the existence of warmer and colder zones, 

 as shown by the limited extent of these glacial deposits. Indeed, 

 it may be questioned if zonal arrangement of temperature has not 

 always been the normal state of the atmosphere, and that the 

 changes have only been toward a greater universal increase or de- 

 crease in temperature, the former permitting expansion of tropical 

 types of organisms, the latter the expansion of the cooler types, 

 and culminating in many cases in periods of glaciation. Evidence 

 of early glaciation has now been recorded from the Lower Huronian 

 of Ontario, Canada (Coleman-19), the pre-Cambric (?) of 

 Varanger Fjord, Norway (Reusch, Strahan-90, etc.), and Spitz- 

 bergen (Gregory-37), the basal Cambric or pre-Cambric of the 

 Yangtse canyon of China (Willis-108), of South Australia (How- 

 chin, David-23, etc.), and Tasmania; of South Africa (Griqua- 

 town series, Rogers-79) ^"<i 'ess definitely from North America 

 and North Asia. The extent in the southern hemisphere was north- 

 ward to 29° in South Africa, and to 32° or 33° in South Australia, 



