Vol. 59 .] 



IN THE CHALK NEAK EOYSTON. 



363 



the Middle Chalk, which forms a scarp to the south, and rises up in 

 the picturesque undulating tract of the Royston Downs. It is well 

 exposed in large pits south of Royston, beyond which the dip-slope 

 has been hollowed into a broad undulating vale bounded by the 

 region of disturbance. (See map, fig. 1.) 



Along the crest of this higher ground, which rises from 400 to a 

 little over 500 feet, the Upper Chalk is capped by Boulder-Clay; 

 this descends southward across the eroded Chalk, and follows the 

 dip-slope into the London Basin. The Chalk-Rock may be traced 

 here and there below the crest, but it extends farther north than 

 represented on the Geological Survey-map near Heydon, as observed 



Fig. 1. — Geological map of the neighbourhood of Royston, based on 

 Sheet Jf7 of the Geological Survey-map. 



Bilderi-si 

 ,_ End/* 



tattle •'•■381- 

 GHishall - ; .-r-- 



h ill 



*;|Barkwk-yJ - 



^Morrice 

 '•"' Green 



ESS Gravel Hill Boulder- Clay I ^Middle & Upper Chalk 



[Scale: 1 inch = 2 miles.] 



Note. — The bigger numerals indicate the chalk-pits described in this paper ; 

 the smaller numerals the altitudes in feet : and the dotted lines indicate 

 the contours. 



by Mr. Whitaker, and it likewise extends farther north at Barley. 

 It was clearly injudicious on the part of those who made the map 

 to connect the line of disturbance with the outcrop of the Chalk- 

 Rock, although in truth it follows close upon it in a general way. 



It was during a series of traverses made in this region in the 

 spring of 1900, and after an examination of a part of the disturbed 

 area, that I was led to question the explanation of the flexure given 

 by Penning ; and I ventured to remark in an article on the Geology 

 of Essex, 



' Whether the disturbance is due to faulting or to the surface-derangements 

 produced by Glacial agents has not been satisfactorily determined.' 1 



It was not, however, until the autumn of last year that I again 

 1 ' Victoria History of the Counties of England : Essex ' vol. i (1903) p. 5. 



2 c* 



