﻿378 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



clinal, to which Mr. Austen directed my attention, and which runs 

 along the Greensand from Chilworth to Weston-street, may further 

 explain the shedding-ofF of some of the coarse detritus of that forma- 

 tion, and serve to account for the unusual quantity of rubbish in 

 the lower part of the depression at Pease Marsh*. The heavy mass 

 of unstratified clay by which the whole is covered, brings it distinctly 

 into the same category as the bone-preserving loam-drift of other 

 places. 



In this, as in all the other tracts hitherto described, I see little 

 chance of being able to separate the drift, which is more or less 

 loose on the sides of the hills, from that which has been cemented and 

 aggregated in combes and hollows, and in the lower parts of which 

 the fossil animals have for the most part been entombed. Such remains 

 have, indeed, been occasionally found considerably above the lower 

 tracts. One example has already been cited on the Downs of Brighton, 

 and another was mentioned to me by Mr. Austen, who was in company 

 with Dr. Buckland when the latter discovered the bone of a Rhi- 

 noceros in loam on the side of the Greensand escarpment, and at some 

 height above the massive slopes of drift on the banks of the Tilling- 

 bourne. I believe, then, that the detritus in and around Pease Marsh 

 was chiefly the result of disturbances of the adjacent strata, whilst 

 broad and torrential bodies of water were moved along under the 

 escarpment of the North Downs, and translated the debris into na- 

 tural depressions. Admitting that the detrital gravel offers clear 

 signs of having been accumulated under water, I cannot, in the oc- 

 casional transverse lamination of the sand, see any proof that the 

 accumulations were not made to a great extent in the same manner 

 as the Brighton breccia. If these false laminae or oblique striae 

 were formed by the sea, they must be assumed to afford also proofs 

 of a shore-deposit. At all events, such false stratification is usually 

 seen where the associated sand and pebbles indicate long-continued 

 abrasion and rolling, which is certainly not the case in the deposit 

 under consideration. 



In this case, a drifting-action, which swept the debris of the adja- 

 cent hills into the hollow of Pease Marsh, might leave them to settle 

 down during a pretty long time, there being no egress for the waters 

 except by the narrow gorge of Guildford. It may also be well ima- 

 gined how, in this pon ding-back of the waters, the coarser and heavier 

 materials would be collocated, just as we now find them, and how the 

 stiff loam, resulting from the final settlement of the smaller particles 

 of matter in the turbid water, would naturally form the covering of 

 the stony debris. It is this thick, impervious, superficial clay which 

 has protected the bones of the large animals from atmospheric action 

 and decay ; whilst the abundance of bones in such hollows can be 

 only, I imagine, satisfactorily explained by supposing that the animals 

 were drifted into these depressions and entombed beneath the mass of 

 detritus. 



* Mr. Austen further spoke to me of evidence he had to prove, that longitudinal 

 fractures have occurred along this valley since the deposit of the drift and 

 gravel. 



