Vol. 59.] DISTURBANCES IN THE CHALK NEAR K0YST0N. 365 



had an opportunity of visiting- the district ; and then, having 

 examined the four pits where the high dips are marked on the 

 Geological Survey-map, I found evidence which satisfied me that 

 the disturbances were due to glacial action — a view con- 

 firmed on a subsequent visit during the present year. 



The four sections are as follows, proceeding from east to west. 



(1) Great Chishall. 



The pit here lies to the north of the village, and the 400-foot con- 

 tour-line passes through it. It has not been worked for some years, 

 and is a good deal overgrown. There was no indication of any definite 

 dip. A few large flints and broken tabular layers w r ere observed. 

 Much of the Chalk was broken and shattered, and near the surface 

 this portion was weathered into rounded lumps. At one spot the 

 interspaces had been filled with ochreous earth, and on the exposed 

 face the chalk-lumps stood out in relief, scored and furrowed by 

 down washes of rain and mud, so as almost to simulate the Boulder- 

 Clay with its glaciated chalk-stones, w T hich on the northern side of 

 the pit rested upon the Chalk. 



This weathered Chalk is of some interest, as from such material, 

 and especially from weathered rounded portions of the Chalk-Rock 

 and harder beds of the Middle Chalk, much of the Chalk-detritus in 

 the Boulder-Clay was no doubt to a large extent derived. 



I could find no evidence of the high dip recorded by Penning. 

 All he says (op. cit. p. 10) is that 



' In the pit north of Great Chishall Church the lines of bedding dip apparently 

 25° N. by W., this being on the line of flexure already noticed.' 



(2) Pinner's Cross, Smith's End,, south of Barley. 



Here in a pit by the roadside, 387^ feet above sea-level, Chalk is 

 exposed with two well-marked bands of nodular- flint, about 6 feet 

 apart, dipping northward at an angle of about 40°. Farther north 

 in the pit there are evidences in the Chalk of what were formerly 

 two other flint-bands, but are now a mixture of broken nodular 

 and tabular flint and flint-chips, the fragments of tabular flint 

 having an approximately vertical position. Still farther north, the 

 Chalk presented at the surface the rubbly weathered aspect else- 

 where observed, and banked against it w T as 6 feet or more of Chalky 

 Boulder-Clay. The Boulder-Clay stones were mainly Chalk, many 

 glaciated, also Oolite, quartz-pebbles, etc. Here the icy agent had 

 evidently pressed against the Chalk, bending it in mass and shivering 

 and streaking out the flint-layers. 



The note on this pit in the Geological Survey Memoir is by 

 Mr. Penning & Mr. Whitaker. 1 The Chalk with flint-layers is 

 stated to dip north by west 40° to 45°, and Boulder-Clay was 

 observed in a hollow in the north. No mention is made of the 

 shattered Chalk, which probably was not then opened up. 



1 ' The Geology of the N.W. Part of Essex & the N.E. Part of Herts, &c.' 

 Mem. Geol. Surv. (1878) p. 7. 



