Noticefi of 3Iemoii's — W. Gib.son — Ooal-D/oas/ire-'i. 79 



!j)lace, and Bourn, soutb of Elswortli, and a few other localities, 

 And like rock was found in Wells. 



The outcrop can be traced almost continuously from a mile west of 

 the brickyard at St. Ives, striking eastwards along the northern flank 

 of the Ouse valley, and passing north of St. Ives to Needingworth ; 

 here it bends abruptly southwards to Holywell and forms a gentle 

 rise. The southern part of the village of Holywell stands on 

 a gravel-capped escarpment of the rock ; a collection of fossils in the 

 Woodwardian Museum, Cambridge, agreeing closely with those of 

 the Elsworth and St. Ives Rocks, was believed to have come from 

 Holywell. East of Holywell the outcrop must cross the Ouse valley; 

 I found traces of the rock in a drain some distance west of Swavesey. 

 From here, south-westwards, it is not seen again till it appears at 

 the surface between Hilton and Conington, where a rock was noted 

 by Mr. Cameron. Southwards from here the outcrop crosses a valley 

 to the rising ground west of Elsworth, through which village 

 a narrow tongue of the rock runs still further south. The main 

 outcrop, however, flanks the northern slope of the drift-capped high 

 ground to the west, and can be traced along the slope through 

 Papworth Everard, westwards to Yelling, following the contour of 

 the ground. At both of these localities there are good and highly 

 fossiliferous exposures in streams. Thence the outcrop disappears 

 southwards under drift, but the rock maybe seen again to the south, 

 less than two miles south of Croxton, in a ditch in the valley of the 

 Abbotsley Brook. 



To the north, east, and south-east of the line of outcrop of this 

 limestone, the ground is occupied by Ampthill Clay, to the west by 

 'Oxford Clay. It will thus be seen that the Elsworth and St. Ives 

 Kocks, besides agreeing closely in their fauna, outcrop along the 

 same line of strike, with Ampthill Clay above and O.Kford Clajj^ below. 

 The dip is always small, and the rock at Bluntisham, if it reaches 

 the surface at all, does so probably as an inlier, though it may be 

 directly connected at the surface with the outcrop east of St. Ives. 



T. — On Eapid CnANGEs in the Tiiickness and Ciiauactee of 

 THE Coal-measures op Noutji Staffokdsiiire.' By W. 

 Gibson, F.G.S. 

 (Communicated by permission of the Director- General of the Geological Survey.) 



YARIABILITY in thickness and character of the strata is 

 universal throughout the Carboniferous period, but is nowhere 

 ■more marked in the Midlands than in the coalfield of the North 

 Staffordshire Potteries. 



This important coalfield consists of two portions. On the east 

 the productive measures lie in a well-marked syncline, while on the 

 west the strata rise in a sharp anticline extending from Silverdale 

 to Talke. The two productive areas are separated by a strip of 

 ground two and a half miles broad, composed of barren upper 

 jneasures. 



' Read before the British Association, Section C (Geology), Bradford, Sept.. 1900. 



