ABSTRACTS OF PAPERS 107 



mind to the French and Italian Alps, the remarkable association of these de- 

 posits on the northern foreland was found to be applicable throughout. Hence 

 the names of four small tributaries of the Danube which cross the outwash 

 deposits on the Bavarian plateau — Giinz, Mindel, Riss, and Wiirm— ^were ap- 

 plied by Penck and Briickner to the 1st, Ilnd, Ilird, and IVth glaciations. 

 The deposits of the Tlird or Riss glaciation in the Swiss and French Jura 

 extend farther out on the foreland than the deposits of the other glacial ad- 

 vances, but in other districts the morainal deposits of the Ilnd or Mindel 

 stage extend beyond that of any other ; hence it is regarded as the most exten- 

 sive of the four alpine glaciations. The morainal and outwash deposits of the 

 1st or Giinz glaciation are least in evidence, while tliose of the IVth or Wiirm 

 glaciation, the last, are most in evidence. 



Tliat the temperature of the alpine region was considerably colder during 

 the stages of glaciation than during the interglacial stages and the Present, 

 wliich is at the close of the retreating liemicycle of the last glaciation, is shown 

 conclusively by the depressed snow-lines. Penck has determined their posi- 

 tion in the Alps for all four glaciations. They have a distribution parallel to 

 that of the present snow-line, but occupying lower levels, namely, Giinz, 1,200 

 meters ; Mindel. 1,350 meters ; Riss, 1,300 meters, and Wiirm 1,200 meters be- 

 low the present snow-line. During the interglacial stages the snow-line was 

 approximately 300 meters higher than the present one. From the Hettinger 

 breccia, near Innsbruck. Penck determined that there was a temperature 

 variation of 1° C. for every 200-metei- change in the altitude of the snow-line. 



The unit of measurement which Penck used in estimating the duration of 

 the Pleistocene period is tlie retreating hemicycle of glaciation of the IVth or 

 Wiirm stage, better known as the post-Glacial period. In the alpine district 

 Penck and Briickner found that in this retreating hemicycle there were three 

 minor advances, called the Biihl, Gschnitz, and Daun stadia. These advances 

 were preceded by a prominent minor retreat — the Achen oscillation. From the 

 lignite deposits of Diirnten, the deposits of the Muota deltas, and the turf de- 

 posits in many of the glacial swamps it has been possible to estimate the 

 duration of this hemicycle of glaciation in years, as follows : 



Suhdivisions of post-Glacial Time 



Years 



Achen oscillation 9,000 



Biihl advance and retreat 5,000 



Gschnitz advance and retreat 4,000 



Daun advance and retreat 3.000 



Age of Copper 1,000 



Post-Copper time 3,000 



Total 25.000 



The csthiiatt" mi tlic duration of post-(iUu-ial tiiiu- in .Vniciica is l)ast'd chielly 

 on the recession of tlic waterfalls of Niagara and Saint .\iitlioM.\. Recently 

 (Coleman' made an csliniate liased on the rate of wave erosion on the shores of 

 Lake Ontario and glacial Lake Iio(|iiois. Twenty-tive thous.md years is a tig- 



' A. V. C'oleuiun : I'roceedinga Twelfth Interu. Geol. Cong., Canada, liil,!. 



