﻿Vol. 64.] CHANNEL OF DRIFT AT HITCHIN. 25 



locality was not far from the edge of the great ice-sheet, where the 

 ice thinned rapidly southwards. The water underneath the ice, if 

 unable to escape northwards, would escape southwards, flowing 

 uphill towards the thin edge of the ice. Water in a sub-Glacial 

 stream did not descend in the same direction as its containing 

 channel ; it resembled a tidal scour which could cut out long 

 channels or basins, with closed ends, in the sea-bed. 



Mr. G. Barrow drew attention to the general resemblance of the 

 phenomena described, and the conformation of the ground, to that 

 seen in the Cleveland area of North-East Yorkshire. The able 

 explanation of the Glacial phenomena of that area, which had been 

 published by Prof. P. F. Kendall, seemed quite applicable to the 

 Hitchin district; and the deep Drift-filled hollow connecting the 

 low-lying area on the north of the town with the valley-system on 

 the south, might easily have been a gorge-like gash, cut through the 

 watershed by a stream flowing along the edge of a mass of melting 

 ice lying in the great hollow north of Hitchin. 



Mr. K. H. TiDDEMAN mentioned that, when he was mapping the 

 ground about 40 years ago, there was a brick-field section of 

 Glacial Drifts at Stevenage, and he was struck by the jSTorthern 

 character of the boulders and more especially by the occurrence 

 among them of Carboniferous Limestone. 



Dr. A. E. Salter was much interested in the detailed account 

 given by the Author of these puzzling deposits in the neighbourhood 

 of the Hitchin and Stevenage Gap. In and to the south of the Gap 

 the gravels could be shown to belong to a ' Drift Series ' in which 

 the higher members had a much simpler composition than those 

 below, and appeared to have been deposited by an old stream 

 draining the Midlands at a time when the Chalk-escarpment was 

 much farther north. The deposits described by the Author were of 

 later date, and belonged to an obsequent stream draining northwards. 

 The northward deepening of the channel excluded the possibility of 

 its being of Glacial origin ; and the fact that it was in places below 

 sea-level pointed to the extreme probability of earth-movements of 

 a regional character having taken place, which caused the old valley 

 to be filled in by debris. There was no necessity and, so far as he 

 could see, no evidence to invoke the aid of a great ice-sheet in the 

 Midlands to explain the phenomena observed by the Author. 



Mr. G. W. YouNGr dwelt on the similarity between the features 

 of the district described in the paper and certain features studied 

 by him along the North Downs. He did not perceive the necessity 

 of invoking the presence of Glacial streams to account for the 

 phenomena, Avhich could be sufficiently explained by long-continued 

 solution of the Chalk. 



Mr. H. B. Woodward remarked that, in a boring at Glemsford, 

 north-west of Sudbury, described by Mr. Whitaker, 470 feet of 

 Drift had been encountered, when Chalk had been expected within 

 about 40 feet of the surface. In this case the base of the Drift was 

 348 feet below Ordnance-datum. The data brought forward by the 

 Author would be of great service in the study of the old channels 



