248 



LANDSLIPS OF THE SILURIAN ROCKS. 



wood-cut at the head of this chapter, to that of the Bone Well, p. 250, and to the 

 following view of the landslip at the Palmer's Cairn. 



34. 



The Palmer's Cairn, from a drawing by Mr. B. W. Evans. 



Landslips of the Silurian Rocks. 



There are some remarkable examples of landslips in the hills west and south-west of 

 Ludlow. As it has been already explained that the rocks in the Ludlow promontory 

 are thrown up on an anticlinal line, and dip away, sometimes at a considerable angle 

 on both sides from a common axis of elevation, it might be supposed, that this sloping 

 position was in itself sufficient to account for masses occasionally sliding down into the 

 lower country. This position alone is, however, inadequate to explain the phenomena 1 . 

 Two other causes have contributed. 



1st. The number of joints by which the overlying rocks are divided. 2ndly. The 

 unctuous nature of the surface of the underlying strata. 



The most striking landslip in the vicinity of Ludlow is at the Churn bank or "Palmer's 



1 Landslips are in general simply subsidences caused by the shrinkage and wearing away of soft and decompo- 

 sing materials when overlaid by solid and heavy masses of rock. The south coast of the Isle of Wight abounds 

 in examples of these subsidences, where the pyritous nature of the blue clay, called gault, occasions its disintegra- 

 tion, and hence the overlying rocks of upper green sand slip down and form an undercliff. There are also many 

 similar subsidences at the escarpment of the oolite and lias in the Cotteswold Hills. 



