546 Rev. W. Loiver Carter — Glaciation of Bon Vctlleija, etc. 



and its consequent predominant power in capturing consequent 

 streams north and south. 



The northwards bend of the Don, after its entrance into tlitt 

 central plain, is due to river capture by a feeder of the Aire. The 

 course of the old Don river from Thorne, along the north side of 

 Hatfield Chase to Adlingfleet on the Trent, is clearly traceable, and 

 was the previous channel of the river before its artificial diversion 

 by the Dutch Kiver to Goole. 



VII, — The Glaciation of the Don and Dearne Valleys. 

 By the Rev, W. Lower Carter, M.A., F.G.S.^ 



TN studying the geological history of the rivers of the Don sj'steni. 

 ray attention was specially directed to the evidences of glacial 

 action in the area, with the object of ascertaining whether glaciation 

 had anything to do with the interesting diversions of the Don, 

 Dearne, and Dove. Certain valleys in the area, also, attracted my 

 attention as possessing abnormal features with respect to the present 

 drainage of the district, and I began to inquire what their relations 

 might be to an altered system of drainage during the Glacial Period, 

 The present paper is an attempt to piece together the scattered 

 glacial evidence, and to ascertain the effect that the advance of 

 a glacier from the north and north-east would have on the drainage 

 of this district, and how far the present valleys would help to 

 explain the water-flow under such conditions. 



1. The Glacial Deposits of the Don System. — These are fragmentary 

 and scattered, and probably but relics of considerable deposits of 

 drift. There are two considerable areas covered with true Boulder- 

 clay in this district — one at Staincross, Carlton, and Eoyston, near 

 Barnsley, and the other at Balby, near Doncaster — each filling 

 a small valley which, since the Glacial Period, has been slightly 

 removed from the line of direct drainage, and hence has escaped 

 denudation. 



The Staincross Boulder-clay, as described in the " Memoir on the 

 Yorkshire Coalfield," consists of two beds of stiff, unstratified till, 

 separated by a thin seam of warp and sand, the lower containing 

 only boulders of Carboniferous Sandstone and Limestone, chert, and 

 a blue, close-grained trap. The upper bed is more sand3% and on 

 the surface have been fotmd many erratics, including a large Shap 

 granite (25 cwt,), Armboth felsite, Threlkeld quartz - porphyry, 

 andesitic ash, rhyolite, etc. These beds fill a hollow cut out of the 

 Woolley Edge Eock ; the junction is much shattered and smashed, 

 and large blocks of the sandstone are embedded in the chi}'. The 

 Yorkshire Boulder Committee report that the country to the north 

 and east of this patch is covered with erratics, and similar Boulder- 

 clays are found at Burton Grange, near Barnsley, and at Ardsley, on 

 the opposite side of the river Dearne. Mr, Walter Hemingway, of 



1 Paper read beiore the British Association, Cambridge, Section C (Geology), 

 August, 1904. 



