384 . REVIEWS 
of accumulation; (5) the rapidity of Alpine glacier movement in the ice age; 
(6) aspect of the different parts of the Alps in the ice age; (7) character 
of the fauna and flora on the north side of the Alps; (8) the loess; (9) the 
climate curve of the glacial period; (10) absolute length of postglacial time 
and of the entire glacial period. 
‘We cannot enter into a review of each of these subjects but will speak 
only of the loess, and of the estimate of the absolute length of the glacial 
period. Typical fossiliferous loess is rather rare in the entire circumference 
of the Alps. Usually the deposit to which this term has been applied is a 
loam having some loess characteristics. This loam is best developed north 
of the Alps and is present on each of the older drift sheets, but not on the 
younger or Wiirm drift. Where there is an overlap of drift sheets it is 
found between them, in the position of an interglacial deposit. But while 
interglacial in position its fauna is not entirely of an interglacial type of 
warm climate animals. The mammalian remains in it are usually of the 
Arcto-Alpine type. Penck makes the suggestion that the loess was deposited 
in advance of a stage of glaciation in a sort of tundra condition with scanty 
vegetation. That the loess of the Riss-Wiirm interval closely preceded the 
Wiirm glaciation is indicated by the character of artifacts found at its base. 
They are closely allied to those which followed the Wiirm glaciation. The 
solution of the loess problem it is thought may be worked out more satis- 
factorily in the broad loess-covered areas of eastern Europe than in the 
rather limited area on the borders of the Alps. 
As to the absolute duration of post-Wiirm time and of the entire glacial 
period, Penck attempts only to present data that will serve to indicate 
roughly its order of size. From Heim’s estimate on the rate of growth of 
the Muota delta and similar estimates elsewhere in the Alps it appears that 
the Biihlstadium of the Wiirm stage of glaciation was reached between 
16,000 and 24,000 years ago. It is safe to conclude, therefore, that the 
culmination of the Wiirm glaciation was somewhat more than 20,000 years 
ago. This estimate is borne out by a study of the Swiss lake dwellings in 
their geologic relations. They are more recent than the Daunstadium, 
and yet lie back at least 4,000 to 4,500 years. Inasmuch as the changes 
effected by geological agencies on the drift of the Riss glaciation are fully 
three times the amount effected in the drift of the Wiirm stage and the 
changes in the Mindel drift twelve times that in the Wiirm, the Riss glacia- 
tion would have culminated fully 60,000 and the Mindel 240,000 years ago. 
The illustrations which accompany the work embrace many excellent 
photographs and several good maps as well as numerous diagrams. Among 
the maps that of the Etsch glacier and the moraine amphitheater of Lago 
