OSBORX. REVIEW OF THE PLEISTOCENE 283 



Third Glacial Stage — Illixoiax, Polaxdiax, Riss 



In North America the Third Glacial Stage is heralded by the advance 

 of a great ice cap radiating from Labrador which sent its glaciers to the 

 south and far southwest, depositing the Illinoian drift which is regarded 

 (Leverett, 1910, p. 315) as of an earlier period than the Polandian or 

 '"'Middle Drift^^ of northern Germany or the Eiss drift of the x^lpine 

 region. This Third glaciation of the Alpine region has a period of ad- 

 vance and retreat which is relatively estiniated by Penck at 20,000 years, 

 the snow line descending 1,250m. With it are associated the "^^high ter- 

 race" deposits of the Alpine region. The Third glaciation was greatly 

 extended along the Ehine, in parts of Switzerland, in France, and in 

 the valley of the Po (Fig. 9). In northern Germany the principal rea- 

 son for separating the "Middle Drift" (Polandian) from the '^TTpper 

 Drift" (Mecklenburgian) is the presence of loess deposits between them 

 which seems to strengthen the evidence for a Third Interglacial interval. 

 These loess deposits are regarded by certain German geologists (Koken) 

 as the continuation of the '^^Older Loess" but by Penck and Leverett they 

 have been regarded as belonging to the "Newer Loess." 



THIRD GLACIAL FAUNA 



The recurrence of a cold climate in Germany is heralded in the 

 Upper Sands of Mauer by the arrival of the reindeer and other arctic 

 types. In the Mammut Lehm of Cannstatt is found a fauna which is 

 regarded by Koken and Schmidt (1912, op. cit.) as contemporaneous 

 with the Third Glacial advance. It is noteworthy as containing two 

 new arrivals from the tundras of the north, namely, the woolly mam- 

 moth {E. primigenius) and woolly rhinoceros (D. antiquitatis) , as well 

 as the reindeer (R. tarandus). The other members of this fauna in- 

 clude two species of horse, the giant deer, the stag, the bison and the 

 urus. "Cannstatt," observes Schmidt (1912, p. 270), "affords a geologi- 

 cal and final connecting link between the Second Interglacial fauna of 

 Mauer and the fauna of Early Palaeolithic [or Third Interglacial] 

 times." If this fauna actually entered Germany during the cold period 

 of the Third glaciation it returned to the north with the approach of the 

 warm-temperate climate of the Third Interglacial Stage, because no 

 trace of it is found until near the close of the Third Interglacial Stage. 



Third Interglacial Stage — Riss-WtJRM^ Sangamon 



The Third Interglacial Stage is shorter than the Second, its geologic 

 and faunal characters are more fullv known, and it embraces the first 



