36 Revieics — Dr. James Geikie's Great Ice Age. 



Treating of the "Valley Drifts," Dr. Geikie comments on the 

 investigations of M. Ladriere in the river valleys of France and 

 the North of Belgium, and considers that they throw great light 

 on the characters of the valley drifts of the Thames. He questions 

 the soundness of dividing these latter into an older high-level and 

 a younger low-level series, and thinks that it is only the bedded 

 gravels of the lower levels which are positively of fluviatile origin ; 

 the high-level loams and angular gravels which extend upwards 

 to the plateaux are more probably local formations like the similar 

 accumulations in Northern France. If those primitive implements, 

 discovered by Harrison at the high-levels on the Chalk plateau of 

 Kent, should be proved eventually to belong to the same age as 

 the Plateau-drifts, the human period would date back to a much 

 earlier period than has hitherto been dreamed of. 



Eeference is also made to the ice-cliffs on the shores of Northera 

 Alaska, described by Dall, which form part of a broad ridge of ice 

 about two miles in width and 250 feet high. Overlying this ice- 

 rock is a bed of clay containing the bones of Mammoth, Horse, Elk, 

 Eeindeer, Musk-Ox, Bison, and Big-Horn. The author supports 

 Dr. Penck's explanation that this ice-sheet must date back to Pleis- 

 tocene times, and that it has the same origin as the frozen bottoms 

 or grounds so commonly met with in the higher latitudes of North 

 America and Asia. This dead ice-sheet, which is now wasting away, 

 must belong to a period when the climate of those regions was much 

 colder than at present. It is not the relic of any glacier, but it 

 probably results from the accumulation of drifted snow in Glacial 

 times. 



Touching the period of the first appearance of Palaeolithic Man 

 in the European area. Dr. Geikie does not consider that we have 

 unequivocal evidence of his presence until the second inter-Glacial 

 epoch [ElejjJias antiqiius stage), when he is characteristically repre- 

 sented by the Chellean or St. Acheul type of flint implements so 

 common in the old river-gravels of the Thames and the Seine. 



Two chapters, containing a very graphic description of the Glacial 

 phenomena of North America, have been written by Prof. T. 0. 

 Charaberlin, who has taken a leading part in the study of the 

 deposits of the Ice Age on that continent. Drift deposits are 

 estimated to cover nearly one-half the area of North America, 

 which means that the glaciers of the Ice Age spread themselves 

 over about 4,000,000 square miles of territory. The main body of 

 ice, appropriately called the Laurentide Glacier, probably originated 

 in more than one centre in Labrador, and in the region north-west 

 of Hudson's Bay, and the nuclei grew until their borders coalesced 

 and the Hudson basin became a great reservoir of ice, from which 

 issued the streams or sheets which covered the eastern five-sixths 

 of the Dominion of Canada, and the larger part of sixteen of the 

 Northern States of the Union and smaller portions of even others. 

 The most southern point reached by the mer-de-glace was in the 

 State of Illinois, between the Ohio and the Mississippi rivers, in 

 lat. 37" 35'. 



