1G President's address. 



and may be traced, according to some geologists, nearly to the western 

 side of England, rising in that direction to a greater height above sea- 

 level. But as it is impossible to prove that all isolated patches of 

 these materials are identical in age, we can only be certain that some 

 of them are older than the next deposit, a boulder clay, which extends 

 over a large part of the lowlands in the Eastern Counties. This has 

 a general resemblance to the Cromer Till, but its matrix is rather 

 more clayey and is variable in colour. In and north of Yorkshire, 

 as well as on the seaward side of the Lincolnshire wolds, it is 

 generally brownish or purplish, but on their western side and as far as 

 the clay goes to the south it is some shade of grey. Near to these 

 wolds, in mid-Norfolk and on the northern margin of Suffolk, ib has 

 a whitish tint, owing to the abundance of comminuted chalk. To the 

 south and west of this area it is dark, from the similar presence of 

 Kimmeridge clay. Yet further west it assumes an intermediate colour 

 by having drawn upon the Oxford clay. This boulder clay, whether 

 the chalky or the purple, in which partings of sand sometimes occur, 

 must once have covered, according to Mr. F. W. Harmer, an area 

 about ten thousand square miles in extent. It spreads like a coverlet 

 over the pre-glacial irregularities of the surface. It caps the hills, 

 attaining sometimes an elevation of fully 500 feet above sea-level; 1 

 it fills up valleys, 3 sometimes partly, sometimes wholly, the original 

 floors of which occasionally lie more than 100 feet below the 

 same level. This boulder clay, often with an underlying sand or 

 gravel, extends to the south as far as the neighbourhood of Muswell Hill 

 and Finchley; hence its margin runs westward through Buckingham- 

 shire, and Mien, bending northwards, passes to the west of Coventry. 

 On this side of the Pennine Chain the matrix of the boulder clay 

 is again reddish, being mainly derived from the sands and marls of 

 the Trias; pieces of chalk and flint are rare (no doubt coming from 

 Antrim), though other rocks are often plentiful enough. Some autho- 

 rities are of opinion that the drift in most parts of Lancashire and 

 Cheshire is separable, as on the eastern coasts, into a lower and an 

 upper boulder clay, with intervening gravelly sands, but others think 

 that the association of the first and third is lenticular rather than 



1 Not far from Royston it is found at a height of 525 feet above O.D. See F. W. 

 Harmer, Pleistocene Period in the Eastern Counties, p. 115. 



2 At Old North Road Station, on a tributary of the Cam, the boulder clay was 

 pierced to a depth of 180 feet, and at Impington it goes to 60 feet below sea-level. 

 Near Hitchin, a hidden valley, traced for seven or eight miles, was proved to a depth of 

 68 feet below O.D., and one near Newport in Essex to 104 feet. Depths were also 

 found of 120 feet at West Horseheath in Suffolk, of 120 feet on low ground two miles 

 S.W. of Sandy in Bedfordshire, of from 100 to 160 feet below the sea at Fossdyke, 

 Long Sutton, and Boston, and at Glemsford in the valley of the Stour 477 feet of drift 

 was passed through before reaching the chalk. See F. W. Harmer, Quart. Journ. Oeol. 

 Soc, Ixiii. (1907), p. 494. 



