292 ANNALS NEW YORK ACADEMY OF SCIENCES 



the time since the last great glacial stage was not less than 31,000 years. 

 Gilbert, Upham and other geologists of the United States Geological 

 Survey after pointing out many sources of error in all such calculations 

 were inclined to the adoption of periods ranging from 6,000 to 10,000 

 years. Gilbert's survey is the most careful which has been made; he 

 estimated (1896) that the gorge of Magara is not more than 7,000 years 

 of age. The Canadian geologist Spencer arrived at a result almost iden- 

 tical with that of Lyell, namely, 32,000 years. 



The most careful estimates on the subdivisions of Postglacial time in 

 Europe are those of Penck (1909, p. 1168) which may be briefly sum- 

 marized as follows : 



IV. 2nd Wurm maximum, beginning of Upper Palaeo- 

 lithic culture 20,000 to 34,000 years 



Achen retreat, period of Aurignacean and Solutrean 

 culture 



Buhl advance, period of early Magdalenian culture 



(Neusch) 16.000 " 24.000 " 



Post-Buhl, period of late Magdalenian culture 10,000 " 16,000 " 



Daun Stage, period of the close of the Upper Palaeo- 

 lithic, Azilian culture 7,000 " 



Age of Copper in Europe 4.000 ' ; 5,000 " 



According to Heim's S3 calculations the period since the deposition of 

 the Buhl moraines in the Lake of Lucerne amounts approximately to 

 16,000 years and if the Magdalenian culture deposits of this formation 

 are of the age of the Buhl advance we mjay estimate with ISTeusch that 

 the Buhl advance occurred at least 24,000 years ago. This advance is a 

 very important period because it represents the last of the Arctic, Tundra 

 and Steppe Faunas in central Europe prior to the establishment of the 

 modern forested conditions and fauna. 



Fauna of the Fourth Glacial Stage. — The severe climate of the Fourth 

 Glacial Stage is indicated by the mammalian life found at Achenheim 

 and Sirgenstein associated with what is known as the "full Mousterian" 

 Palaeolithic culture (Schmidt, 1912). Here for the first time there is a 

 predominance of the Tundra Fauna (fifteen species) as well as the ad- 

 vent of the Steppe Fauna (two species), while the Forest Fauna (seven 

 species) and Meadow Fauna (four species) are still represented. The 

 straight-tusked elephant (E. antiquus) and broad-nosed rhinoceros (D. 

 merchii) have disappeared and are now replaced by the woolly elephant 

 (E. primigenias) and woolly rhinoceros (D. antiquitatis) . The mam- 



83 Heim, A. : "uber das absolute Alter der Biszeit." Viei-tel.jahrsschrift der natur- 

 forsch. Ges. in Zurich, Jahrg. 39. No. 2, pp. 180-186. 1894. 



