S. V. Wood— Origin of the Loess. 415 



How far the " clay with flints," which covers and conceals large 

 areas* of chalk in the southern half of England, corresponds in its 

 mineral constituents, and the arrangement of these, with the Picardy 

 limon, I am unable to say, being now physically unable to examine 

 it ; but in the memoir of the Geological Sui-vey for Sheet 13 it is 

 stated to be met with only on the Upper Chalk, i.e, the chalk with 

 flints; and it is this clay formation which, judging from the notes 

 engraved on the Survey Maps, wraps all those higher chalk elevations, 

 beyond the limit to which the land ice reached, that from their 

 constituting areas higher than the line up to which the submergence 

 of the major glaciation is shown by the evidence of gravel beds to 

 have extended, or elevations so little below this line that they 

 became land before that glaciation passed away, that I have referred 

 to the action in question during the major glaciation. 



The material which in England has, in my view, originated from 

 this action during the minor glaciation only, is in the south-east of 

 England represented by brick-earth, which, in the neighbourhood 

 of the Upper Chalk, is, like the Picardy limon, full of angular 

 fragments of flint. This, travelling from the chalk of the South 

 Downs, has " ravined " ^ and overspi-ead the shingly sands with 

 marine mollusca (all of living British species), occupying the area 

 between those Downs and the British Channel — sands which I 

 regard as coeval with the CyreAia formation of the Thames Valley, 

 which, in the parts of it (such as the London Koad pit at Uford) 

 that were above the river level of the time, is overlain by the 

 corresponding atmospheric material of this glaciation, but in the 

 parts of it that were below this level is covered with the river 

 gravel of the same glaciation, as at the Uphall Eield, Uford. 



In other places, such as the limestone districts of South Lincoln- 

 shire, which were buried under the land ice of the major glaciation, 

 and the medium and lower elevations of the south-west of England, 

 which, covered by the great submergence, but not reached by the land 

 ice of the major glaciation, did not become land until that glaciation 

 had passed away, the material thus originating during the minor is 

 the loam with angular fragments which ca]3s the Lincolnshire lime- 

 stone, the loam with Mammalian remains which wraps the Jurassic 

 beds of Wilts and Somerset, and the intrusive cave-earth generally 

 of the South-west of England. These forms of it vary according to 

 the character of the parent formation upon which the process has 

 operated ; and it is the same material which, under one or other of 

 these guises, buries the cliffs that skirted the British Channel coast 

 at the time of the incidence of the minor glaciation, and of which 

 sections have occurred at Brighton, Isle of Wight Foreland, Portland, 

 and Sili Bay, Glamorganshire. 



In the North of England, as far as the land ice supj)lied moraine, 

 the formation contemporaneous with this material of the minor 



1 This brick-earfh with angular fragments of flint is shown by Prof. Prestwich 

 (Q.J.G.S. vol. XV. p. 216) to overlie and " ravine " these sands in the sections of them 

 which he gives from Avisford, just as M. de Mercey describes the base of the limon 

 to " ravine " the subjacent deposits in Picardy. 



