﻿MURCHISON FLINT DRIFT OF S.E. ENGLAND. 3,">7 



see the reason why. In the apex to which the Greensand is re- 

 duced in this situation, there are no courses of clinkers, nor any escarp- 

 ments of the formation whence such materials could have been de- 

 rived. After passing, however, the hills of Trotton, Midhurst, 

 and Petworth, in which clinkers abound, we can easily understand 

 how a drift or current, acting from west to east, should have merged 

 its chalk-flints with debris of the harder beds of the sandstone over 

 which it passed, and have also translated fragments of chert from 

 the still lower and well-exposed inferior member of the same formation. 

 This view supposes, that the movements which fractured the rocks 

 along this western portion of the great anticlinal of the Weald were 

 accompanied by a sudden rush of waters. 



The loftiest position occupied by the flint-drift to the east of Peters- 

 field has been already alluded to as the summit of Rogate Common, 

 about 500 feet above the sea, where the Lower Greensand forms 

 the southern flank of the deep denudation of Weald Clay in Harting 

 Combe (see fig. 3). By consulting the geological map I formerly 

 published*, the reader will see that the Lower Greensand there sub- 

 tends the Weald-clay at a sharp angle, the point of which is pre- 

 cisely directed to the angle of confluence of the chalk, whence this 

 flint-drift is supposed to have proceeded. The flints which lie on 

 the summit of the escarpment have been chiefly shivered to small 

 angular fragments, and intermixed with detritus of the rock in situ ; 

 but larger flints and in greater quantities have been carried down the 

 sides of the southern escarpment and advance over undulations of the 

 Lower Greensand to the edge of the clay in the deepest part of the 

 depression. In trending the northern and north-western sides of this 

 deep combe, the geologist can, however, detect no flint-detritus ; the 

 sand-rock being everywhere at the surface. This is well seen on the 

 edge of Rake Common, along which the London and Portsmouth 

 road passes, and which overhangs the picturesque Harting Combe. 



This portion of the escarpment has been quite excluded from the 

 drift ; but immediately to the south of the public-house called the 

 " Jolly Drovers," the zone of broken flints is met with, and is seen 

 to descend into the combe, and to keep to its southern side only, 

 under the escarpment before alluded to (see fig. 3). Much of the 

 drift has doubtless passed to the south side of the combe by a 

 marked aperture in the ridge of Lower Greensand, caused by a rup- 

 ture of the strata in the acute angle into which the formation is there 

 thrown. Now this break and depression at the very apex of the Lower 

 Greensand, and where the strata are highly inclined, point directlv 

 to the greater break and depression in the chalk west of Petersfield. 



In these phsenomena, and in the fact that no trainee of flints can 

 be traced from the nearest chalk escarpments, or those of Hawkley 

 Hills across Rake Common, whilst a zone of such is distinctly trace- 

 able along the southern side of the great Wealden anticlinal, we have, 

 I think, good grounds for believing, that the drift in question pro- 

 ceeded, as before said, from the angle of fracture and denudation of the 



* See Trans. Geol. Soc. Lond. N. S. vol. ii. PI. XIV. 



