﻿MR. W. HILL ON A DEEP [Feb. I908, 



On a Deep Channel of Dkift at Hitchin (Hertfordshire). 

 By William Hill, F.G.S. (Read December 18th, 1907.) 



Contents. 



Page 



I. Introduction 8 



II. Physical Features of the Hitchin and Stevenage Gap . 9 



III. Evidence of the Deep Channel in the Drift 13 



IV. Materials filling the Hitchin and Stevenage Gap 19 



V. Summary 21 



I. Introduction. 



Deep channels filled with Drift occurring in Scotland and in the 

 North of England have long been noticed by geologists,^ and more 

 recently the existence of similar buried valleys has been discovered 

 in the East of England. In 1890 Mr. W. Whitaker " drew attention 

 to a deep channel of Drift in the valley of the Cam ; and in 1898 

 Dr. A. Irving recorded a great depth of Drift in the valley of the 

 Stort.' 



It has long been known that a considerable thickness of Drift 

 covers the Chalk immediately to the south of Hitchin, wells and 

 road-cuttings indicating that deposits of sand, gravel, or Boulder- 

 Clay were at least 60 feet thick in certain localities ; a boring at 

 Messrs. Lucas & Co.'s brewery at Hitchin in the year 1831 ^ was 

 carried to a depth of 466 feet, passing through 3 feet of soil and 

 77 feet of sand. But the Chalk is so frequently seen that an 

 exceptional thickness of Drift was unsuspected. 



During the last few years five borings have been made in the 

 neighbourhood of Hitchin, all of which have disclosed a greater 

 thickness of Drift than was expected. They happen to have been 

 made in a line running about north and south nearly at right angles 

 to the outcrop of the Chalk, the southernmost being 3 miles south 

 of Hitchin, and the northernmost 4 miles north of the town. The 

 object of this paper is to record these borings, which, with other 

 evidence, seem to point to the existence of a deep and narrow 

 channel of Drift, the length of which (as at present ascertained) is 

 about 7 miles, although probably it extends farther. 



^ Sir A. Geikie, ' On the Phenomena of the Glacial Drift of Scotland ' 

 Trans. Geol. Soc. Glasgow, vol. i, pt. ii (1863) pp. 49-66 ; J. Croll, ' Two River- 

 Coannels buried under Drift' Trans. Edin. Geol. Soc, vol. i (1869-70) 

 pp. 330-45 ; T. M. Reade, ' The Buried Valley of the Mersey ' Proc. Liverpool 

 Geol. Soc. vol. ii (1873-74) Sess. xiv, p. 42. 



■^ ' On a Deep Channel of Drift in the Valley of the Cam, Essex ' Quart. 

 Journ. Geol. Soc. vol. xlvi, p. 333 ; see also the same author's ' Water-Supply 

 of Suffolk ' Mem. Geol. Surv. 1906, p. 3 ct passim. 



3 Proc. Geol. Assoc, vol, xv, p. 224. 



■* ' The Geology of the London Basin ' Mem. Geol. Surv. vol. iv (1872) 

 p. 453. 



