LANDSLIPS OF THE SILURIAN ROCKS. 



249 



Cairn," where large masses of the Aymestry limestone have slid down from the crest 

 of the hill into a comb, exposing the sloping surface of the Lower Ludlow rock over 

 which they have slipped, as explained in the above wood-cut. The area here affected 

 exceeds fifty acres. 



The wood-cut exhibits the slope of the beds, and the joints which divide the rock into 

 lozenge-shaped masses : the thin layer of unctuous clay or "Walker's soap" which was 

 spread over the inclined floor of flagstone, facilitated the descent of the disrupted masses. 



Of the two causes, the second or jointed condition of the strata has been perhaps the 

 most efficient ; and the descent of the masses would doubtless be aided by ordinary at- 

 mospheric agents, and perhaps determined by the breaking up of a powerful frost, &c. 



The same causes have led to similar slips in other parts of the environs of Ludlow, 

 as on the steep external slope of the ridge called Brindgwood Chace, at a spot called 

 Wheeler Vallet's Wood ; while another has occurred in the grounds of Ferney Hall. 

 At the latter place the rocks not being inclined at so high an angle and not impending 

 over so deep a comb as at the Palmer's Cairn, have been slightly moved down the gentle 

 slope, but the joints of the rock have opened out to yawning fissures, extending over a 

 surface of about seven acres. These chasms being now well wooded are very orna- 

 mental. On my first visit to the country they appeared inexplicable or were generally 

 supposed to be old stone quarries, and it was not until I had seen the remarkable land- 

 slip of Ludlow rocks, in Marcle Hill, (to be described in the chapter on the valley of 

 Woolhope) that I became acquainted with the true causes of the open chasms of Ferney 

 Hall and the great slip of Palmer's Cairn. All these phenomena agree so closely, with 

 slight differences of scenery, that the description of one may serve for all. The slip of 

 Marcle Hill, however, is recorded by our old chroniclers and will be noticed at greater 

 length. Those in the environs of Ludlow may also have occurred in modern times, 

 but from their remote situations or the absence of local historians, the dates of the ca- 

 tastrophes have not been preserved 1 . 



Besides these greater and more complex landslips of the Ludlow rocks, others of more simple 

 characters occur. One of the most striking cases of this sort happened about fifty years ago on the 

 right bank of the Severn, one mile west of the entrance to Coalbrook Dale, and destroyed a house 

 and barn. This was doubtless occasioned by the disintegration and subsidence of the incoherent 

 shale which here occupies the banks of the Severn. This shale forms the unstable support of heavy 

 overlying masses of the carboniferous rocks; and its partial subsidence is what might very naturally 

 have been expected. Several acres of ground were thrown into a highly varied outline, and now 

 compose little conical hillocks separated by deep hollows, the whole extending in a deltoid form 

 from the side of the hill whence they slipped, to the high road in the valley of the Severn. 



1 Dr. Lloyd, who has proved so good a coadjutor, and who first directed my attention to the fissures at Ferney 

 Hall, has acquainted me that recently, on Mr. Duppa Lloyd's estate at Longville, a large mass of Caradoc Sand- 

 stone slid smoothly and rapidly down from its parent seat. The strata are there inclined about 15°, and unctuous 

 clay underlaid the mass affected. 



