THE "WONDER." — A MODERN LANDSLIP. 



435 



to many ecroulemens of Alpine tracts. Dislocated masses of the Upper Ludlow rock, in all amount- 

 ing to about 20 acres, still attest the extent of the calamity, by exposing gaping fissures between 

 them. Some of the masses have slid so gradually and equably as to preserve the angle of inclination 

 of 12° or 15° which they had before they broke away from the parent mass, and these have trees and 

 grass growing luxuriantly on their summits. Others have been thrown upon their edges into in- 

 clined positions. The broken rocks have advanced, however, but a very short distance upon the 

 ground below them, and the slip is therefore quite insignificant, when compared with the " ecroule- 

 mens " of the Alps, nor is it by any means so striking as the slip of the Palmer's Cairn near Lud- 

 low. (See wood-cut, p. 248,) 



As the strata are slightly inclined in the adjoining ridge, or in that portion of it from which this 

 mass has been detached, it is more difficult to imagine why the subsidence should specially have 

 taken place at this point ; though a consideration of the structure of the Ludlow rock will facilitate 

 the explanation. It has been before remarked, that it is a common feature of this rock to be split 

 into lozenge-shaped masses, by joints which are more or less vertical to the surfaces of the strata. 

 We have only to imagine this mass of Ludlow rock replaced in its former position, with several such 

 cracks at its upper extremity, and that water descending from the ridge above, and percolating 

 for ages through the apertures, gradually washed away some underlying, perishable way-boards. 

 We can then readily suppose, that having been so far loosened, it would, upon some slight exciting 

 cause, slide down into the valley beneath. An unusual flood, the breaking up of a long frost, or 

 other ordinary atmospheric changes would in such a condition of things be quite adequate to pro- 

 duce this "wonder," particularly in this district, where the lower grounds consisting of soft clays 

 near the junction with the Old Red Sandstone, are very likely to have given way, and thus to have 

 aided the descent of this mass of rock. 



The explanation previously given of similar phenomena in the neighbourhood of 

 Ludlow, may, indeed, be applied to this and all other slips in rocks having the same 

 structure. Owing to the broken condition of the strata, I could not detect beneath the 

 dislocated mass a layer of unctuous shale or fuller's earth which might have facilitated 

 its descent on the inclined plane in the manner before suggested ; but I have little doubt 

 that such "Walker's Soap" existed, for it abounds in the Ludlow formation of this 

 neighbourhood, and is largely extracted for economical uses at Shucknell Hill 1 . (See 

 Map.) I have minutely described this, because although noticed by foreign writers 2 , it 

 has escaped the observation of native geologists. We now learn, that so far from being 

 an isolated phenomenon, it is one of frequent occurrence in the Upper Silurian rocks, 

 resulting naturally from their structure and position. 



In the account given of the old chroniclers, no part seems less intelligible, than the 



1 Shucknell Hill, distant only two miles from the northern edge of the Woolhope elevation, is a distinct 

 Silurian mass surrounded by Old Red Sandstone and composed exclusively of Ludlow rocks, the calcareous or 

 central band of which (representing the Aymestry limestone) is exposed in sharply inclined strata and largely 

 quarried for road making. The major axis of Shucknell Hill is from W.S.W. to E.N.E., and therefore at right 

 angles to that of Woolhope, and is coincident with the remarkable trap dyke of Bartestree described pp. 185 

 and 186. 



2 Bertrand, Revolutions du Globe, Paris. The account is taken from the old English writers. 



