460 J. Prestwich, Esq., on the 



Notwithstanding all the dislocations, disturbances, and changes of level, which we have enume- 

 rated above, the coal-measures and the other formations are not much contorted ; neither is the 

 angle of dip materially affected. Were it not for the actual exposure of a fault by means of sec- 

 tions, or more generally in the pits, its existence could rarely be inferred from the relative dips 

 of the disjointed strata. I now allude to a case where a repetition of similar lithological characters 

 renders a positive recognition of the majority of the strata impossible. For example : from the 

 dip at Bullock's Leasows and Randley, an observer miglit easily suppose a perfect continuity of 

 strata between those two places — the planes having a similar inclination, and in no wise indicating 

 the important intervening fractures. (See Section 6.) From the dip of the strata at Amies and 

 Caughley, they might be supposed to range likewise uninterruptedly between those two places ; 

 whereas a disjointed section of New Red Sandstone separates them. 



We might also imagine, from the dip of the carboniferous series at Steeraways, that a consider- 

 able fault ranged between that highly-inclined outcrop and the nearly horizontal strata half a mile 

 to the east, but only small slips have been noticed. (See Section 5.) So on both sides of all the 

 large faults, the disjointed strata preserve a near parailelijm of dip. 



Thus, notwithstanding all the dislocations, the deposits maintain a general dip eastward, de- 

 pendent upon the main line of disturbance or the protrusion of the igneous axis of the Wrekin. 

 (See Sections 3, 4, 5, 6, 7, &c.*). 



Diluvium, or Drift. 



The district bears evidence of a powerful aqueous action on its surface, 

 a large portion of it being covered with thick accumulations of gravel and 

 sand. These deposits are frequently separable into two divisions : the lower 

 consisting of a fine red sand, associated with beds of angular and rounded peb- 

 bles, derived from the adjacent rocks ; and the other of gravel, composed also 

 of rolled pebbles of the neighbouring formations, with a few small boulders 

 and pebbles of granite and older rocks, imbedded in a coarse, reddish sand, 

 frequently much mixed with clay. Where the sand is wanting, the separation 

 of the two gravels is almost impracticable. 



The sand occurs in only limited patches, though of considerable thickness, 

 both in the valleys and on moderate elevations, but more especially on the 

 sides of hills. Thin, distant seams of marl and clay show the irregular and cur- 



* From the phenomena detailed in the preceding pages, it appears, that the coal-field is but a 

 fractured portion of a larger deposit ; the remainder of which must, therefore, exist below the 

 surrounding new red sandstone. From the large faults which we know to traverse the coal 

 strata, and many of which are doubtlessly prolonged through the new red sandstone, the former 

 may, in some places, be brought within a moderate depth from the surface. Still, from the 

 proved irregular persistence of the coal and ironstone strata, it would require great caution in 

 inferring the existence of those beds below any given portion of the new red sandstone, except 

 in the places adjacent to the line of fault, where the coal-measures are well-developed and pro- 

 ductive at their abutment. 



