454 T. V. Holmes — On Deneholes and Bell Pits. 



a year and a half after the publication of our Denehole Eeport.^ 

 Mr. J. B. Ogle, a member of the Geologists' Association, was then 

 good enough to tell me of some subsidences which had recently 

 occurred between Stifford and Grays Thurrock. Close to but west 

 of the road connecting Grays and Stifford, just where the boundary 

 between the two parishes comes to the road from the east, were two 

 holes, the result of a recent subsidence. They were nearly cylindrical 

 in shape, each being between 7 and 8 feet in diameter and from 

 9 to 10 feet apart. Mr. Frank, residing at The Lodge, Stifford, had 

 kindly provided a ladder, and we descended into the pit. The sides 

 of the shaft were approximately vertical, and the section displayed 

 consisted of — 



Eed clay ... ... ... ... ... about 8 feet. 



Yellow sand ... ... ... about 2 to 3 „ 



Gravel, green-coated flints here and there 1 to 2 „ 



Chalk. 



On reaching the Chalk the pit had been at once widened out, the 

 thickness of the Chalk roof increasing as the distance from the 

 shaft increased. It was found possible to creep through a chalk- 

 roofed excavation connecting the two openings, which were similar 

 in the section they presented and in general appearance. The chalk 

 had been worked in various directions somewhat irregularly and 

 without any regard to permanent stability. There were many 

 pick-marks here and there. The shape and size of the workings 

 were much obscured by fallen material, but judging from what we 

 saw they may have extended to a distance of 20 to 25 feet from the 

 centre of the shaft we descended. I remarked in the Essex 

 Naturalist at the time, and still think, that " the purpose of the 

 excavators seems to have been simply the extraction of chalk for 

 agricultural purposes." The workings had apparently been filled 

 with vegetable i-efuse capped by earth, which had remained firm 

 long after the stuff beneath had rotted away, a sudden subsidence 

 being the result. Another subsidence had occurred in the road 

 nearer Stifford shortly before our visit, but had naturally been 

 filled up as soon as possible. 



It would seem that these workings for chalk must be of consider- 

 able age. About 150 yards westward there is a huge open chalk- 

 pit, which had then been disused about 30 years. And two others 

 of much smaller size, but also disused, may be seen, a little 

 northward and a little southward of the subsidences, east of the 

 road. The large chalk-pit may cover perhaps 12 to 14 acres. 

 The workings at the subsidences can hardly have been made after 

 any of these open pits were begun, but must have been of much 

 earlier date. 



The beds above the Chalk at these workings appear to be old 

 river-deposits. Similar beds were also visible at the northern end 

 of the very large chalk-pit west of the road between Grays and 

 Stifford, but much nearer Grays. The old river, which formed 



1 See Essex JVaturalist, vol. iii (1889), p. 183. 



