Coast o/Cuherhole Point, near Axmouth, 161 



dercliff of South-eastern Devon, in the acale and picturesque 

 effect of its features, is far superior to that of the Isle pf 

 Wight. 



It will be necessary, in order to give a clear idea of the 

 causes which have produced these convulsions, to premise a 

 few words as to the nature and distribution of the rock masses 

 on which they have acted. The tract of Downs ranging along 

 the coast is here capped by a stratum of chalk, this rests on 

 series of beds of consolidated sandstone, alternating with seams 

 of that variety of flints called Chert ; beneath these more than 

 one hundred feet of loose sand, locally (from an obvious etymo- 

 logy) termed fox mould ; this bed affords the principal cause 

 of the disturbances in question, for it imbibes all the atmo- 

 spherical water falling on the surface, and as it rests on reten- 

 tive beds of clay (belonging to the lias formation) these 

 waters are here held up and flow out in springs along the 

 margin of this deposit wherever it is exposed by the slope 

 of the ground, as is necessarily the case all along the face of 

 these Downs where they break down to the sea ; the springs 

 thus issuing wash out with them a very sensible portion of the 

 loose deposit of fox mould, through which they flow — and such 

 an action is of course greatly aggravated by the inordinate con- 

 tinuance of wet weather in a season such as has lately prevail- 

 ed. Thus considerable portions of the fox mould being gra- 

 dually removed along the lines through which these subterra- 

 nean springs have found their course, the superstrata will re- 

 main completely undermined ; and as an excessively wet season 

 will, by saturating the whole with moisture, increase the weight 

 of the incumbent mass, at the same time that (as we have seen) 

 it withdraws the support, it is easy to conceive that cracks will 

 in process of time be formed, and that the undermined por- 

 tions of the superstrata will be precipitated into the hollows 

 prepared beneath them. And further, as the adjacent masses 

 of rock, even where not thus completely undermined, rest on a 

 slippery basis of watery sand, the motion originally impressed 

 by the falling in of an actually undermined tract will readily 

 be propagated to a considerable extent in an internal direc- 

 tion. 



VOL. XXIX. NO. LVII. ^JULY 1840. L 



