134 Geology of the South East of Dorsetshire. 



but think, that since that time the cliff has become lower at 

 that point, owing to atmospheric agency, assisted by the 

 waves, which have reduced the height, by throwing the cliff 

 back, into a hollow in the surface. But the cliff immediately 

 rises to the south of Old Harry. 



Dr. M. speaks of a tabular mass, half way to Ballard Point, 

 about 100 feet high, (3 in fig. 13) ; and says, 50 years ago, 

 there was a connection between it and the main land. This 

 I have heard before and since ; but, if 50 years have been suf- 

 ficient to separate so far, this pillar of "so exceedingly hard'''' 

 chalk, the waves, assisted by rain, and frost, and fog, those 

 mighty agents of destruction, far more insidious and powerful 

 than old Neptune himself, with all his battering rams, will, 

 assuredly, save me from the charge of exaggeration in my o- 

 pinion, (expressed at p. 419), that "two other and larger pin- 

 nacles will not remain many years uncompleted." I have in 

 this paper assigned a sufficient reason, viz. the existence of 

 vertical cracks, which traverse the whole strata. Whether 

 these cracks be true joints, or mechanical dislocations, I will 

 not pretend to say ; though I think they imply, that at the 

 north end of the promontory, there have been upheavings and 

 depressions, collateral with those near Ballard Point. If Dr. 

 M. doubts my assumption of the measure of decay in these 

 cliffs, let him compare Mr. Webster's drawing, made in 1813, 

 with what he himself saw in 1833. 



Lastly, Dr. Mitchell " endeavours to remove an error which 

 has appeared in Sir Henry Englefield's work, and is also in 

 that of Messrs. Coneybeare and Phillips," (p. 591). This 

 supposed " error" alludes to the "shivered" flints of the Pur- 

 beck range. Now it is hardly fair to attribute such an "error" 

 to the works in question, when they do not commit it. Mr. 

 Webster actually says ; " These flints do not frequently fall 

 into fragments in the hand, as those in the Isle of Wight,'''' 

 (the charge alleged against this author being, that he says 

 they do), "the parts being firmly imbedded in the chalk ; but 

 there is the same variety in the size of the fragments, from 

 large pieces to the finest powder." (Englefield's I. Wight, 

 p. 167). The fact is, there are whole flints and broken flints, 

 all through the Purbeck chalk range; and at Corfe Castle, the 

 fragments of flint are separated, in the same nodules, by chalk 

 and crystallised carbonate of lime, to considerable distances, 

 even where the casts of fossils, (such as Galerites, Spatangi, 

 &c.) exist, the flinty mass is traversed by cracks and little 

 faults, which have been cemented by carbonate of lime, or a 

 siliceous paste of another colour. And oftentimes, the casts 

 of these fossils, which, though in flint, are of carbonate of 



