OSBOR^\ REVIEW OF THE PLEISTOCENE 



231 



are of later date than tlie marine Pliocene deposits of southern Europe. 

 Before any of these glacial deposits occurred there was an elevation of 

 the marine Pliocene strata along the southern Alpine borders from sea 

 level to a height of from 300-500m. ; there also occurred erosion of these 

 marine strata by rivers. Thus in the valley of the Po there is a consid- 

 erable time interval between the closing marine conditions of the Plio- 

 cene and the opening Pleistocene conditions. In the valley of the Ehone 

 also there is a marked interruption between the strata of the Pliocene and 

 of the Glacial epochs, the latter overlying the strata recogiiized as Upper 

 Pliocene^, which in turn overlie the marine Pliocene.^''' 



This interval between the Pliocene and Pleistocene corresponds with 

 very important changes which occur in the mammalian life of Europe, 

 namely, in the extinction of many characteristic Pliocene mammals, such 

 as the anthropoid apes, the antelopes and the mastodons. 



S/erra de Credos Alps Mis 



Mas Mrs j Pyrenees Mrs 



Strair of Gibraltar 



Garonne Rhone 

 Valley Valley 



North Sk^ger 

 Sea Rak 



PROriLE OF PAST AND PRESENT SNOWLINES AND GLACIERS OF EUROPE 

 Fig. 4. — Theoretic snoic levels during the G-lavial Epoch 



Prepared under the direction of the author by Chester A. Keeds from data given by 

 J. Geilxie. Penck. Briichner. Leverett and Stieler's Hand-Atlas, December. 1914. 



The traces of four different glacial advances and retreats observed 

 around the northern slopes of the Alps by Penck and Briickner^^ were fol- 

 lowed with their ^^river drifts'' and moraines down the Danube to the 

 neighborhood of Vienna: they were found to be clearly marked in the re- 

 gion of the upper Ehine and of the Ehone around Lyons, and distin- 

 guishable both by the greater or the less extension of their borders and by 

 the greater or less erosion which has occurred in the intervals between 

 their successive depositions. These four advances were named respec- 

 tively the Griinz, the Mindel. the Eiss and the Wiirni. 



As an instance of the disparity between the duration of these several 

 glacial advances with the accompanying descent of the ice and snow line, 

 the old moraines of the Eiss or third glaciation form a girdle around tlie 

 more recent Wlirm or fourth glaciation, proving that the Eiss wa,s not 



" Op. at., pp. 654-6.55. 

 ^^ Op. cit., p. 47. 



