776 



SCIENCE 



[N. S. Vol. XXXVIII. No. 987 



" Der Mensch. der Vorzeit " very appropri- 

 ately constitutes Volume I of a monumental 

 work in three volumes^ entitled " Der Mensch 

 aller Zeiten Natur and Kultur der Volker der 

 Erde." 



By way of introduction the author gives a 

 resume of ancient cosmogony and archeology 

 as seen through medieval eyes, and the found- 

 ing of geology, paleontology and prehistoric 

 archeology as exact sciences. 



The key to the Glacial period is found in the 

 existing glaciers, which still cover about 10 

 per cent, of the land surface of the earth. 

 The author is particularly well qualified to 

 treat of the geology of the Ice Age as he has 

 made a special study of the glacial phenomena 

 in the French Pyrenees, where he found a suc- 

 cession of four terraces in the Garonne and 

 Ariege valleys precisely as had been noted 

 previously by Penck and Briickner in the foot- 

 hills of the Alps. These he refers to the four 

 glacial epochs for which he accepts Penck's 

 terminology, beginning with the oldest : Giinz, 

 Mindel, Eiss and Wiirm. In the Garonne 

 valley the Giinz terrace is 150 meters above 

 the present stream bed ; while the Mindel, Eiss 

 and Wiirm terraces are 100, 55 and 15 meters 

 respectively above the present stream. 



The great loess mantel stretching from 

 southern England, Belgium and northern 

 France across Germany to the Carpathian 

 Mountains, Obermaier considers an eolian 

 formation. His conclusion is based on the 

 position, structure and content of the loess. 

 In the Eiesengebirge it reaches an elevation of 

 400 meters above the sea; the lines of stratifi- 

 cation are not such as would be formed in 

 water; and the animal remains found in the 

 loess are for the most part land shells, fresh- 

 water shells being rare and fishes entirely 

 wanting. 



While the great loess mantel is evidently 

 eolian, there are restricted loess deposits con- 

 nected with valley terraces that owe their for- 

 mation to the agency of water. The loess of 



1 The authors of the other volumes are Ferdinand 

 Birkner, Wilhelm Schmidt, Ferdinand Hestermann 

 and Theodor Stratmann. 



western and central Europe is exclusively of 

 Quaternary age, but must be considered as 

 having been deposited at various epochs. The 

 author believes the latest loess to be post-gla- 

 cial, whUe Penck would place it as far back 

 as the maximum extension of the Wiirm gla- 

 ciation. 



The possible causes of the Ice Age may be 

 classed as astronomical, geological and phys- 

 ical. The basis for the astronomical theories 

 is that the movement of the earth is influenced 

 not only by the sun, but also by the planets; 

 the latter, although much smaller than the 

 sun, are nevertheless able to bring about 

 periodic changes in the form of the earth's 

 orbit and the inclination of the earth's axis to 

 the ecliptic. The precision of the equinoxes 

 should also be considered. No one of the 

 periodic changes in the movement of the earth 

 is sufficient in itself to bring about a succes- 

 sion of glacial and interglacial epochs. 



From the viewpoint of geology the legends 

 concerning the lost Atlantis, or those pointing 

 to a possible bridge across the north Atlantic, 

 must ever remain purely legends. Does the 

 theory of Kreichgauer furnish a key to the Ice 

 Age? The author thinks favorably of it. 

 Kreichgauer supposes the earth's axis to re- 

 main fixed and the earth's crust to move slowly 

 on the molten mass within. Thus a spot on 

 the equator might in the course of time find 

 itself over one of the poles. Paleontology and 

 the distribution of glacial phenomena are 

 thought to offer evidences in support of this 

 hypothesis. 



As possible physical causes there may be 

 cited changes in the character of the atmos- 

 phere, rendering it less penetrable by the sun's 

 rays. According to Svante Arrhenius, a 

 period of high percentage of carbonic acid in 

 the air would be a period of cold, and vice 

 versa. Periods of great volcanic activity 

 would thus correspond to periods of cold; and 

 the Quaternary volcanoes of Auvergne and the 

 Ehine are known to have been active during a 

 cold period. Of all the theories, the author 

 gives preference to Kreichgauer's. Whether 

 the glacial epochs were synchronous in the 

 northern and southern hemispheres he is un- 



