864 Mr. H. E. Strickland on the Elevatory Forces 



dykes which Professor Phillips was the first to describe. By 

 penetrating the shales (as trap-dykes often do) in the planes of 

 stratification, they would produce an apj)earancc of contempora- 

 neity, though their real dates might be long subsequent. 



The district here referred to seems to be exactly analogous to 

 the well-known elevatioii crater of Woolhope, distant only seven 

 or eight miles to the westward, in which we also see the ineffec- 

 tual struggles of a focus of volcanic energy to burst through the 

 incumbent strata. Here also the concealed volcano has left a 

 collateral proof of its existence in the single basaltic dyke of 

 Bartestree Chapel. 



These detached indications seem to show that the volcanic 

 matter which underlies, and which has elevated this region, is 

 different in mineral character from the more ancient syenite of 

 Malvern, and is probably more allied to greenstone or basalt. 

 The trap-rocks of Wyre Forest, north of Abberley, further corro- 

 borate this view. 



In tracing to the north or south that long line of dislocation 

 of which the IMalvern Hills form a part, we find a continuation 

 of analogous phsenomena more or less modified by local circum- 

 stances. The Abberley range of hills is, as is ably shown by 

 Professor Phillips (Mem. Geol. Surv., vol. ii. p. 145), completely 

 analogous to the Malvern district ; the chief difference being, 

 that the syenitic axis which upheaved the Silurian rocks is here 

 almost wholly concealed from view, and (with one small excep- 

 tion) is only known by its effects. The Silurian and Old Red 

 formations are here, as on the west of Malvern, overturned for a 

 distance of several miles. This remarkable phsenomenon may, 

 I think, be explained in a simpler mode than either of those pro- 

 posed by Professor Phillips. All that is requisite is to resolve 

 a certain portion of the vertical uplifting force into a lateral 

 direction. Now it is certain that an enormous fault-line runs 

 along the eastern side of all the disturbed and elevated district, 

 and that the downcast region on the east has remained relatively 

 rigid and unmoved. In accordance with the well-known law 

 that the plane of a fault (almost invariably) dips towards the 

 downcast side, it is evident that this oblique surface would act 

 mechanically as an inclined plane or wedge, in reference to a 

 vertical uplifting of the strata on the west, and would force them 

 over to a certain distance in a lateral direction. (See Plate I.)* 



The same lateral force would explain the sharp anticlinal 



* A very analogous case occurs at Hohnstein in Saxony, where a mass 

 of granite, upheaved in a sohd state, has not only elevated but overturned 

 the contiguous strata, causing beds of the Jurassic series to repose upon 

 Cretaceous ones. (SeeCotta, Geognostische Wanderungen, Dresden, 1838.) 



