62 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



bands of sand and shingle, with sea-shells. One of these, and the 

 principal one, having a continuous range over a very wide area of the 

 Sussex levels, occurs towards the upper part of this accumulation ; 

 but there are other seams which are fairly included in it. In these 

 last shells are scarce, and usually much broken ; being much in the 

 condition of those to be met with in the upper portions of gravel- 

 beaches ; but their variety is by no means so great as the present 

 beach affords. 



The upper shell-zone contains abundantly a large form of Cardium 

 edide : at one place there was a most wonderful collection in a band 

 of fine sand, but owing to their matrix the shells were in a very friable 

 condition. It pould be seen that very many had the valves joined ; 

 some few were closed, but mostly gaping ; with these was Turritella 

 terebra. This condition of the bivalve shells indicates a disturbance 

 of the sea-bed where these animals had lived, and which had trans- 

 ferred them to the higher marginal zone. 



The materials of this bed are much water-worn, and consist mostly 

 of chalk-flints. There are also pebbles of granite, porphyry, and 

 other old and crystalline rocks, but which also are much water-worn, 

 and never of large size. It is for this reason, and from the circum- 

 stance that the larger blocks of the subjacent drift-formation have 

 never been disturbed by the process of denudation which the latter has 

 experienced, that I am disposed to consider that the foreign materials 

 of this stage have been derived from the waste of the subjacent one, 

 and that the conditions under which the larger blocks have been 

 conveyed to the places where we now find them, had altogether 

 ceased. (See p. 57.) 



I believe it to be this stratum which, appearing in many places 

 over the Sussex-levels, and along the courses of some of the rivers 

 (as the Arun), with its characteristic sea-shells, has been taken as an 

 indication of a recent change of level, whereas it is truly anterior 

 to the spread of the brickearth-formation. It is to this level, too, 

 that I think must be referred the old sea-beach from Brighton to 

 Rottingdean. Of this age also are the beds of sand, shingle, and 

 clay described by Sir Roderick Murchison as seen between Brighton 

 and Hove, and of the identity of which with the old beach at Kemp 

 Town he considers there is the clearest proof. 



4. The BHck-earth. — The uppermost deposit on the coast-section 

 consists of a uniform layer of imstratified clay, with an average thick- 

 ness of from 2 to 3 feet. (Fig. 4, b.) It is of a dark-chocolate colour, 

 contains small sharp splinters of flint, and occasionally a few rounded 

 pebbles, which have apparently been derived from some lower tertiary 

 beds. These materials are dispersed irregularly throughout the mass. 



In following this bed from the coast-section inwards, it is seen 

 to form part of that great layer of earthy matter which overlies all 

 the gravel and other beds of the Sussex-levels, and is extensively 

 used for brick-making. The beds fittest for this purpose are those 

 nearest the hills, and where tertiary clay- strata come to the surface ; 

 but throughout it is characterized by the small angular fragments of 

 flint, which, when near high ground, are often arranged somewhat 



