H. J. Loive — Devonshire Geology. 275 



to their original basin. In quotation ante, p. 270, lie thinks the lake 

 theory unsatisfactory ; in the next extract he seems to accept that 

 theory. In another, p. 271, he considers the clays might have been 

 formed in lakes or catchment basins in the course of the Eocene 

 river ; but Mr. Eeid writes with conviction that the Bovey beds are 

 simply an outlier as expressed by Mr. Gardner in citation on p. 271. 



Now the assumption that the beds were formed in a lake by 

 an affluent of the Eocene river does not disturb the old theory at 

 all, and in consequence needs no comment. That the lake might 

 have been one in the course of the main stream would raise the 

 question, how are the clays further eastward to be accounted for 

 if the river was cleared of its detrital material by the Bovey lake ? 



The consideration of the Bovey area as a ' catchment ' basin 

 would imply that close under the slopes of Dartmoor low-lying land 

 9 by 4 miles in dimensions received a part only of the water and 

 detritus of a river flowing eastward along its southern border. 

 That in this way from 300 to 400 feet of deposits were formed 

 without the help of streams from land bordering it on the north ; 

 for although the Dartmoor granite is the undoubted origin of the 

 clay and sand material of these deposits, yet streams coming directly 

 into the area therefrom are precluded by the terms of the hypothesis. 

 Now streams have flowed down that slope of Dartmoor continuously 

 since even pre-Eocene times, so that the ' catchment ' supposition 

 can hardly be maintained in the case. 



It is, however, the ' outlier ' view that demands the closest 

 consideration. This implies that the deposits were spread more 

 or less regularly over the area before indicated, extending some 

 100 miles east and west. Data are wanting to get an estimate 

 of the width of the supposed basin, but if the gravels may be used 

 as such it might be taken to be from 12 to 25 miles westward, and 

 about 25 miles wide towards its eastern limits. This hypothetical 

 ' lagoon ' during the deposition within it of the Middle Eocene 

 fresh- water beds received apparently very little else than the detrital 

 material of Dartmoor, from which the clays and accompanying sands 

 were derived. Now, however, we may regard the distribution of 

 these beds over this area ; from the figures available respecting the 

 present existing remnants ! the supposition that they were continuous 

 implies such an enormous amount of derived material as to seem 

 incompatible with the reputed source of supply. Mr. Gardner 

 accepts Pengelly's estimate of the Bovey clays as " 440 feet without 

 bottom being reached," and his own estimate of the fresh-water 

 series of Bournemouth is from 600 to 700 feet thick. Eegarding 

 these deposits, 80 miles apart, as continuous in the light of the 

 remarks that they " have been mainly derived from an old rock 

 area," and " are derived from the weathering of the Dartmoor 

 granite" {vide ante), we are impressed with the enormous demand 

 made upon that comparatively small granite mass. Put into terms 

 of roughly comparable measurement, it may be represented thus : — 

 A part only of an area of less than 250 square miles called upon to 

 supply material hundreds of feet in thickness over more than 1,500 



