32 Reviews — i)r. James Geihie's Great Ice Age. 



in England before the epoch of maximum glaciation. From the 

 time of the Eed Crag onwards, the number of northern forms of 

 life continues to increase, whilst the southern forms die out, so that 

 in the Cbillesford and Weybourn Crags the Molluscan fauna has 

 a thoroughly Arctic facies. On the other hand, the flora and fauna 

 of the next succeeding Forest-bed series is of a temperate character, 

 very similar to that which now prevails ; and Mr. Clement Reid, who 

 has so carefully worked out the Forest-bed flora, considers that it 

 may have been contemporaneous in our area with the Arctic fauna 

 of the Weybourn Crag. Dr. Geikie, however, does not think this 

 probable, and favours the view that the Forest-bed was formed in 

 a comparatively genial climate which succeeded the Arctic one of 

 the Weybourn Crag. Be this as it may, there is no doubt whatever 

 of the Arctic character of the climate which followed the period of 

 the Forest-bed, as shown by the plants discovered by Nathorst in 

 the overlying fresh -water bed, which indicate, according to Mr. 

 Eeid, a lowering of the temperature by about 20°. A still more 

 severe period of cold accompanied the formation of the Cromer Till, 

 the intermediate sands, gravels, and clays, and the contorted drift 

 with which all geologists are so familiar. With respect to the 

 " contorted drift," the author now regards it as a peculiar form of 

 ground-moraine, in which masses of Chalk and different kinds of 

 Pliocene and Pleistocene beds are jumbled together in the wildest 

 confusion, and yet, curiously enough, this kneaded-up material 

 usually rests with a horizontal junction on quite undisturbed beds. 

 The intercalated beds of sand and gravel in the Boulder-clay series 

 are attributed to the action of water flowing beneath the ice-sheet, 

 and the author concludes that all the Pleistocene accumulations of 

 the Cromer Cliffs are of glacial and subglacial origin, and belong to 

 one and the same period of glaciation. 



As to the succession of the glacial deposits in Lincolnshire and 

 Eastern Yorkshire, Dr. Geikie agrees with Mr. Lamplugh that the 

 Sewerby beach and the Speeton shell-bed are probably contem- 

 poraneous with the Leda my alls bed of the Norfolk cliffs, and that 

 they were formed during mild conditions of climate before the 

 advent of the great mer-de-glace, which crept in upon the land from 

 the north-east, out of the bed of the North Sea, and produced the 

 basement or lowest Boulder-clay. The Scandinavian erratics in this 

 clay may have travelled all the way from their place of origin 

 underneath the ice- sheet; the suggestion, which recently appeared 

 in this Magazine, that they had been transported as ballast in the 

 Vikings' ships, is of too late a date to be noticed by the author. The 

 formation of the purple clay, with its associated sands and gravels, 

 has been referred by Mr. Lamplugh to the period of the retreat of 

 the margin of the ice from Holderness. In this clay the erratics are 

 more conspicuously of home origin. The marine gravels of Kelsea 

 Hill are attributed to a later date, when the land had been submerged 

 for 100 feet, and the presence of the Pleistocene Mammalia and of 

 the fresh-water shell, Gorhicvla fluminalis, are accepted as proving an 

 extended period of genial conditions since the time of the maximum 



