420 J. Prestwich, Esq., on the 



ward of Much Wenlock, the limestone escarpment has a very regular strike 

 south-west and north-east, and the strata at the outcrop, along its summit, 

 dip about 25° south-east, the inclination decreasing- in following the direction 

 of the dip. About two miles north of Much Wenlock, the escarpment is 

 broken through by numerous transverse glens, marking the range of large 

 faults ; and the strata dip in all directions. The synchnal line along Farly 

 Glen, and the dome-shaped structure of Tickwood, resulted apparently from 

 these fractures and disturbances*. 



The belt of hmestone reassumes its usual regularity at Benthall Edge, with 

 a strike E.N.E. and a dip from 20° to 25° S.S.E. At the large quarry about 

 midway along this ridge, the basseting edges of the limestone dip at an angle 

 of 26° S.S.E., but the dip rapidly decreases as the strata recede from their 

 outcrop, being only 16° at the distance of 70 feet from that point; and still 

 further in the same direction, the strata are comparatively horizontal, and are 

 overlaid unconformably by the coal-measures. 



This arrangement prevails the whole length of the escarpment, but at Lin- 

 coln Hill, the strata, instead of forming, as at Benthall Edge, a short and rapid 

 curve, are very singularly contorted. These undulations are well exposed in 

 the limestone caverns, in the eastern flanks of the hill, and extend along the 

 plane of the rock to a depth of 100 yards from its basset. The strata dip at an 

 angle of about 55° for the first few yards ; they then begin to curve gradually ; 

 but about 80 yards from the outcrop the undulations present a series of very 

 slightly convex planes, 20 yards in breadth, and separated by rapid, step-formed 

 descents, from 4 to 6 yards in the fall, and the apex of the curves exhibiting 

 no fracture in the limestone. 



The escarpment of this rock finally disappears below the coal-measures, 

 near Castle Green, and though it does not crop out, it has been proved to 

 continue as an underground ridge in the same direction, at several coal-pits 

 lying in that plane in the parish of Madeley. (See Map and Sections.) 



The upper beds of the Wenlock limestone are thin and argillaceous, and 

 of a light gray or blue colour. In proportion as the series descend, so the 

 strata are thicker and more compact. The central beds are extensively quar- 

 ried, both for agricultural purposes and the iron furnaces. At Wenlock, 

 Gleedon Hill, and Tickwood they are extremely pure, of a very light gray 

 colour, but sometimes tinged or rather speckled of a light flesh colour, owing 

 to the imbedded Encrinites. The structure is concretionary and the fracture 



* Mr. Philips notices similar effects from like causes in the scar limestone of Yorkshire, (see 

 Phil. Geol. of Yorkshire, vol. ii. p. 114.) Mr. Murchison also explains the phaenomena of Wool- 

 hope, and the Wren's Nest by the doctrine of valleys of elevation — Silurian System, p. 428, et sea., 

 and p. 4S3, ct seq. 



