GRAVEL AND BOULDERS IN THE WEST OF ENGLAND. 199 
angular and slightly rolled detritus of the adjacent hills, so that we 
have pebbles of the porphyry and greenstone of Charnwood Forest, 
at Abingdon, and Oxford; and pebbles of the rocks near Birmingham, 
at Henley and Maidenhead, and in Hyde Park. 
It appears then we have evidence, that a current from the north 
has drifted to their present place, along the whole east coast of 
England, that portion of the pebbles there occurring, which cannot 
have been derived from this country; a certain number of them may 
possibly have come from the coast of Scotland, but the greater part 
have apparently been drifted from the other side of the German Ocean. 
It appears also that there are proofs of a similar current having passed 
over the central and south-eastern parts of England; and if we 
examine its western side, we find similar evidence of a violent rush 
of waters from the north, in the pebbles and blocks of granite and 
sienite of a very peculiar character, that have been drifted from the 
Criftle Mountain in Galloway, across Solway Frith, to the north base 
of the mountains of Cumberland, where I have seen them at a spot 
called Shalk, between Ireby and Carlisle; whilst pebbles and large 
blocks of another kind of granite have been drifted in still greater 
numbers from Ravenglass, on the west of Cumberland, over the plains 
of Lancashire, Cheshire, and Staffordshire: their course is marked in 
Mr. Greenough’s map of England, and they lie in masses of some tons 
weight on the west of the towns of Macclesfield and Stafford, and 
between Dudley and Bridgnorth. 
In an appendix, I shall subjoin the details of the evidence we 
find in the south-west of England, to show the excavation of valleys 
along the coast of Devon and Dorset, by the denuding force of the 
