98 



material, must have traversed hundreds of miles to procure with 

 infinite labour foreign stones of enormous size and of no greater 

 virtue than those they found ready to hand. That these stones 

 were found in situ is a far more probable story, and compares 

 favourably with Mr. Clement Reid's idea of a supposed erratic- 

 strewn plain now sunk beneath the sea (page 80). 



Passing by a series of observations presented to us on pages 81 

 and 82 of facts bearing on possible glacial action in several districts, 

 including Dr. Colley March's interesting reference to his finds in 

 the Scilly Islands, all of which afford — I submit — evidence of the 

 action of floating ice, and not of an ice-sheet, we return to Dorset- 

 shire and visit Corfe Castle, on pages 83 and 84. It is of course 

 possible that during glacial times, ice may have caused the blocking 

 of one of the two streams which carved out the double valley ; but 

 there is surely a simpler explanation for this historic gap ? I would 

 suggest that the primary cutting down of the summit of the 

 anticlinal by the combined streams had been gradually widened by 

 the water passage, aided by sub-aerial denudation of the. chalk 

 sides, so that presently there was insufficient water to fill it, and 

 the two brooks began each to plough up a channel for itself, one at 

 the west and the other at the east side of the cutting. The middle 

 area would then become first an island, and then gradually form 

 the summit of the Corfe monticle, as each stream gradually 

 carved out and cut down its own side of the hill. This theory is 

 merely suggested to supplement the late Mr. Huddleston's view — 

 which certainly seems the simplest of those offered us — and to avoid 

 the necessity of presuming ice-action where other causes suffice. 



It seems rather unnecessary to invent a glacier to account for 

 Chesil Beach. Where are the mountains to supply such a glacier ? 

 Even in the glacial period glaciers could hardly have marched 

 about the country like lions seeking what they might devour. I 

 thought it was acknowledged that the bed of Kimmeridge clay, 

 upon which the beach rests, was in its normal geological position, 

 conformable and continuous with the adjacent bed of the Dorset 

 coast ; also that the clay had been cut down by marine erosion to 

 that point at which, covered by the shingle, it has since been protected 

 from wave action. The occurrence of the Fleet behind the beach 

 is certainly more difficult of explanation, if, as Dr. Colley March 

 assures us, it could not have been scoured out by water current. 

 Writing on this, Mr. Strahan says : " That the Fleet is the result 

 of sub-aerial denudation, as claimed by Messrs. Bristow and 

 Whitaker, seems scarcely to admit of doubt."* Had the clay bed 

 of the beach been due to ice-action, is it probable that a glacier of 

 this power could have left no traces in its course on shore beyond 

 the striated gravel near Chickerel ? The subject is a difficult one, 

 but perhaps further researches may throw fresh light upon it. 



The discovery of a supposed moraine at Chesilton is very 

 interesting. Certainly the specimens showed us last month may 

 well have been brought by ice. Not having visited the spot, one is 

 not qualified to discuss it. I would only suggest that the material 



* Memoirs of the Geological Survey, Isle of Purbeck, p. 206. 



