﻿MURCHISON — FLINT DRIFT OF S.E. ENGLAND. 



377 



In ascending a tributary of the Tillingbourne to the south of Al- 

 bury Heath*, I perceived, that whilst the summits and slopes of the 

 hills of Lower Greensand were there entirely denuded, the little up- 

 land valley (as exposed by deep drains) is filled, from side to side, with 

 coarse debris of the harder beds of the surrounding formation (chert, 

 clinkers, &c), but void of chalk-flints. 



In looking to these facts, and to the distribution of the rock-masses 

 and the form of the country, we may, I think, apply nearly the same 

 reasoning as to the environs of Petersfield and Pulborough. That 

 the mass of the drift accumulated in Pease Marsh and the valley of the 

 Tillingbourne proceeded from the nearest great fractures in the chalk 

 and greensand admits, I think, of little doubt. Thus, the clinkers 

 that constitute one half of the detrital matter have been washed in 

 from the surrounding hills of Lower Greensand. The mass of the 

 flints may, indeed, have been well derived from the narrow impend- 

 ing broken chalk-ridge, and the fissure by which the Wey escapes. 

 For here, as in parts of the South Downs, there is evidence of anti- 

 clinal elevation as well as transverse fracture, to which Mr. Austen 

 called my attention, and by which, in one spot near St. Martha's 

 Chapel f, the Gault is thrown up in a mural form, together with the 

 Chalk. The few fragments of grey-wether or tertiary sandstone which 

 occur in the drift are, I have no doubt, remnants of a former cap- 

 ping of tfhe adjacent chalk-ridge at Guildford. 



Again, when we move southwards into any adjacent depression, we 

 find that the only debris is that of the greensandstone of the adjacent 

 and surrounding formations. Thus, I repeat, that we here have 

 pretty much the same results of longitudinal and transverse fractures of 

 the adjacent rocks along a west and east zone, as we have in the south- 

 western extremity of the region or other side of the great axis. 



Under such circumstances, and particularly when I see this drift 

 at Albury and on the sides of the Tillingbourne, and again to the 

 south of Wonersh, mounting to heights of 60 and 70 feet above its 

 level in Pease Marsh, 1 can neither admit that it could have been 

 accumulated in a lake, nor, in looking to the exclusively terrestrial 

 remains which are found in the deposit, can I believe that this was 

 an estuary of a former sea. Anyone who examines the highly 

 eroded surface of the chalk, and the fractured tertiary detritus above 

 Merrow, and, passing over the summit, descends into the beautiful 

 valley of the Tillingbourne, whether near Chilworth or at Weston- 

 street, but particularly at the latter, will see what quantities of 

 shattered chalk-flints are even now lying dislodged from their na- 

 tural position, and overlapping successively the escarpment-edges 

 of the Lower Chalk and Upper Greensand. A very little more 

 transport down the steep, in an ancient condition of things, and 

 when the depressions were occupied by broad bodies of water up- 

 wards of 200 feet above the present drainage, and they would be 

 aggregated in the depressions like the " Combe-rock" at Weston- 

 street. I am disposed, indeed, to think that a low imperfect anti- 



* In company with Mr. H. Drummond, M.P., of Albury Park. 



f The Lower Greensand at St. Martha's Chapel is 580 feet above the sea. 



