1861.] KEY BOTET DEPOSIT. 19 



what would be expected imder the conditions above given ; and that 

 though in the Bovey deposit we do not find a uniform arrangement 

 of strata on each side of the basin, but a great development of fine 

 material on one side, attended by a corresponding regularity, — and 

 a paucity of clay and much irregularity on the other, yet, supposing 

 tliat the rivers and streams of the ancient lake ran into it from 

 similar situations to those now running into its bed, we could not 

 expect the same degree of regularity as in the more simple form of 

 the supposed lake and single river. 



Before the lake became di-ained by the bursting through, or wear- 

 ing down, of the channel between Buckland Point and Hackney, 

 the " Head " on the clay had probably run out over the greater por- 

 tion of the higher part of the deposit, every little stream, of course, 

 bringing its ovm formation from the hiUs ; hence the flint, chert, 

 and fossils from the Greensand. After the waters had retreated, 

 the Teign, the Bovey, and other streams must have channelled out 

 the loose material of the '' Head" considerably ; and to this cause 

 may be attributed the valley at the upper part of the basin, and 

 others canying small watercourses. 



The author proceeds to state his belief that the Bovey deposits 

 were composed of detritus derived from the surrounding hills, and 

 quietly deposited, with no more disturbance than the occasional 

 flood : that if the relative level of sea and land has been disturbed, 

 it has been over a large area, leaving the physical characters of the 

 country comparatively unaltered ; because he does not observe similar 

 deposits on the neighbouring hills ; because the basin appears to 

 have been always limited by the existing hiUs ; because there are 

 no slips or faults in the deposit; because the mode of deposition would 

 account for the inclination of the beds, and for their local variations. 

 Some of the beds have a dip of 45° or 50°, and the lignite at the Decoy 

 (fig. 3) is almost perpendicular ; but this is only for about 15 or 18 

 feet ; afterwards it takes an angle of 40° or 50°. The perpendi- 

 cularity of these beds is accounted for by the author, by the supposi- 

 tion that they have been bent outwards by the slipping or forcing 

 out of the lower wedge-shaped beds, when in a soft state, pressed 

 down by the weight of the " Head." 



Recurring, says the author, to the opinion I have heard expressed 

 by some geologists, that the Bovey deposit is a portion of more widely 

 spread beds that once existed over a large area, I can only say, it may 

 he so; but up to the present time 1 have never seen the least sign of 

 the clay and accompanying beds, cither in the valley of the Dart, on 

 the one hand, or that of the Exe, on the other. On the northern slope 

 of Dartmoor, it is true, near the village of Morton, there is a deposit 

 much resembling that of the Bovey basin, both in regard to the 

 quality of the clay and the manner in which it lies*; but the great 

 similarity in general features of the Morton basin with that of Bovey 

 explains the derivation of the clay-beds, and adds additional proof 

 that my view of the Bovey beds is correct. The Morton clays are 

 deposited in beds sloping at angles similar to those of Bovey ; the 

 deposit is cntiixly surrounded by hills, except at one point, where a 



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