H. J. Lotve — Sketch of a bit of Dartmoor. 399 



from the hardest varieties of the granite, viz., the schorl rock, elvans, 

 and quartz veins ; but the former constitutes much the greater 

 proportion of the coarser material, and there is very little of the 

 more easily disintegrated porphyritic granite to be met with. 



Receding from the foot of the Tor the drift material becomes 

 finer, and finally as sand mixed with humus forms cultivable land. 

 A cutting made by a roadway through a portion on the opposite side 

 of the strip from the Tor shows sand of varying degrees of coarse- 

 ness, roughly stratified, with the finer material increasing upwards. 



From the description it will be seen that the materials are all 

 water-worn and water-borne, and are sorted out after the manner 

 of river drift where a stream, turned from a direct course, by wearing 

 away the opposing mass loses much of its carrying power while 

 increasing the area of drift deposit at the bend.^ 



There is, then, little doubt that this drift now lying far above the 

 present bed of the Eovey stream is the work of that river, a deposit 

 made in its earlier and probably more vigorous age, when its course 

 was along the north side of Hunters' Tor and down the broader 

 Moretonhampstead valley, now occupied by the puny Wray stream. 

 But while it was expending its force in shearing a drift area on 

 the north side of the Tor, a small stream on the south-west of the 

 Cleave was cutting its way back in a north-westerly direction and 

 thus gradually approaching the bend of the larger stream, until 

 the gradually narrowing ridge dividing the principal from the 

 subordinate valley became worn down to the level of the higher 

 and main stream, when it would leave its old circuitous course and 

 descend the more direct and precipitous one towards its destination. 

 The old course and the approaching valleys are indicated on the 

 following map. 



Half a mile south of the river-deserted patch of gravel and near 

 to the newer and present course of the Bovey stream stands the 

 farmstead of Foxworthy, remembered probably by some who may 

 read this note as the moorland retreat of a well-known geologist 

 and friend of geologists— Mr. A. R. Hunt, M.A., F.G.S., etc., who 

 directed the Geologists' Association for the day and entertained them 

 at this delightful spot (Easter, 1900).* To him I am much indebted 

 for geological help, and indeed he introduced the problem of the 

 drift, a solution of which is here offered. Close to Foxworthy estate 

 is a peculiarity in the channel of the river that may be accounted 

 for by the turning of the greater stream into the course of a small 

 tributary. Horsham Steps (see Map 1) is an extraordinary aggre- 

 gation of granite boulders choking the river channel for a considerable 

 number of yards. These boulders are, generally speaking, very 

 massive, so that the interstices are suificiently large to allow all the 

 water to pass through them except at times of freshets of more than 

 average volume. The boulders are so piled together that they form 

 a natural fording-place at most states of the stream, which at 



1 Eeferences to the valley deposits are made in papers by G. W. Ormerod, Quart. 

 Journ. Geol. Soc, vol. xxiii, p. 425, and Prestwich, Geol. Mag. for 1898, p. 414. 



2 Proc. Geol. Assoc, vol. xvi, p. 430, 



