Notices of Memoirs — F. W. Harmer — The Eastern Glacier. 509 



the well-known Cambridge Greensand pbosphatic seam, lies uncon- 

 formably upon the Gault. It is succeeded by various divisions of 

 the Chalk up to the zone of Micraster. 



The glacial deposits consist chiefly of the Chalky Boulder-clay ; 

 the great boulder at Ely is also of interest. 



The Pleistocene gravels include the plateau gravels on the Chalk 

 hills and the well-known mamrualiferous gravels forming terraces on 

 the valley-sides. The March marine gravels are usually correlated 

 with the gravels of one of these terraces. 



Alluvium is found on the valley-bottoms, and in the fenland peat 

 occurs with intercalated patches of Scrobicularia clay. The peat 

 contains the fauna of Neolithic and later times. 



III. —The Great Eastern Glacier. By F. W. Harmer, F.G.S.^ 



THIS name is proposed for the great ice-stream the moraine 

 of which, the Chalky Boulder-clay, covers an area of more 

 than 5,000 square miles in the east of England, frequently attaining 

 a thickness of more than 100 feet. 



As far back as 1858, Trimmer, a pioneer in glacial investigation, 

 pointed out that the county of Norfolk had been twice invaded 

 by ice, first from the North Sea and then from the west, the 

 resulting detritus in the one case being characterised by igneous 

 blocks, some of them of Scandinavian origin ; and in the other 

 by a predominance of Jurassic material. The first invasion is 

 represented by the Cromer Till and the Contorted Drift of the 

 Norfolk coast; the second, by the Chalky Boulder-clay, the subject 

 of the present paper, which does not occur in north-east Norfolk. 



The region covered by the latter deposit, which extends over 

 a great part of the eastern counties of England, has a palmate 

 outline, its lobes, which radiate from the great depression of the 

 Lincolnshire and Cambridgeshire Fens, being of unequal length. 

 The latter region was not only the centre whence the Chalky Boulder- 

 clay of the southern part of the area was distributed, but also the 

 quarry out of which was excavated most of the enormous mass of 

 Jurassic material of which the matrix of this deposit is so largely 

 composed. 



The present physiographical features of the east of England 

 resemble, moi'e or less, those which obtained in Glacial times, the 

 Drift deposits not only covering the plateaux between the valleys 

 in which the rivers of the district now run, but descending into 

 them, sometimes to below sea-level. Hence by the study of the 

 existing contours, aided by that of well-borings, it is possible to 

 obtain a general idea of the pre- Glacial topography by which the 

 movements of the ice must have been determined or influenced. 



Although the erratics of the Chalky Boulder-clay are more or less 

 of a similar character over a wide area, indicating that it was 

 distributed from a common centre, the predominant character of its 



^ Abstract of paper read before the British Association, Cambridge, Section 

 (Geology), August, 1904. 



