0)1 the Agricultural Geology of England and Wales. 475 



if, as seems probable, the gravel once formed a continuous stratum 

 at the highest level at which it is found. Some very instructive 

 sections, showing the relations of the surface soil to this gravel 



No. 2. 



Christchurch. Hordwell. 



a Warp or surface loam. & Flint gravel. c Freshwater eocene. 



, Upper JJagshot. Headon-HiU sand. e Barton clay^ | Middle Basshots. 



and the older tertiaries, are afforded by the cliffs which extend 

 along the Hampshire coast from Christchurch to Hordwell. The 

 gravel covers the denuded surface of the older tertiaries, and is 

 covered by a warp, which deepens in the hollows, and thins off 

 towards the summits, as in the annexed diagram. 



We could never find anything in the gravel of Dorset and 

 Hants but flints and fragments of stone derived from the eocene 

 tertiaries. Shells, we believe, have never been seen in it. 



In the upper part of the elephant bed at Brighton, which is a 

 mass of fragmentary chalk, we observed a small boulder of trap ; 

 and Dr. Mantell describes water-worn blocks of granite, porphyry, 

 slate, limestone, and tertiary sandstone in the shingle, or ancient 

 beach, containing marine remains, on which the elephant bed 

 rests.* The Brighton deposits bear more resemblance than any 

 of those south of the Thames to portions of the upper erratics of 

 Norfolk. 



From the general difference of character exhibited by this 

 southern gravel, and from its being in immediate contact with the 

 eocene tertiaries or the chalk, the pliocene formation of the crag 

 being absent, some geologists refer it to a more ancient epoch 

 than that of the erratics of Norfolk, which, it will be remembered, 

 are superior to the pliocene crag. We are inclined, however, to 

 regard it as a modification of the upper erratics of the district 

 north of the Thames, the modifications of composition being, per- 

 haps, due to different conditions of climate prevailmg during its 

 formation, and perhaps to movements of disturbance, by which the 

 strata of the chalk were fractured during its formation. It must 

 be borne in mind that while the chalk strata north of the Thames 

 have been thrown up with a strike from north-east to south-west, 

 in ridges whose direction has influenced the distribution of the 

 superficial deposit, they have an east and west strike south of the 

 Thames. This east and west line of disturbance, which upset the 

 chalk and tertiaries of the Isle of Wight, threw up the parallel 

 chalk ridges of the North and South Downs, laid open the Weald 



* Mantell's Geology of the South-East of England. 



