24 ON THE LONDON CLAY FORMATION 



ance of the London clay,— dark brown or blueish clay, with 

 rarely any fossil remains. The base of this low cliff is usu- 

 ally covered up with shingle, which extends towards the low 

 water mark for about fifteen or twenty yards, and there it ter- 

 minates. The remaining space intervening between the foot 

 of the shingle bed and low water mark, is in many places at 

 least 80 or 100 yards in length, and presents a surface, under 

 ordinary circumstances, of a clean, dark greyish-green sand, 

 with scarcely a single pebble to be seen : but after some 

 tides it is literally strewed with thousands of the detached 

 valves of Venericardia planicosta, and of other shells, while 

 at other times scarcely a shell can be found. The part of the 

 bay most interesting to the geologist, is that immediately in 

 the neighbourhood of Bracklesham Barn, especially at about 

 a furlong to the east of that spot, where there is a small 

 break or chine in the low clay cliff. At this place, and at a 

 few paces east and west of it, beneath about six or seven feet 

 of clay, there is a stratum of light green marly sand, abound- 

 ing in remains of Venericardia planicosia and other shells, 

 but which is frequently entirely hidden by thrown-up shingle, 

 and it is very rarely that more than a few feet in length of 

 this bed can be seen. It is from this bed, or from one ex- 

 ceedingly like it, somewhat lower in the series, that perhaps 

 most of the interesting shells of this district are to be pro- 

 cured. If we proceed from this little break or chine west- 

 ward, for about forty paces parallel to the coast, and then in 

 the direction of a line at a right angle to the cliff, and at the 

 time of low water, we shall find, near the low- water-mark, 

 the bed we have described as abounding in fossils, exposed 

 by the action of the sea in the most favourable manner. At 

 this spot Venericardia planicosia is found literally by thou- 

 sands, with the valves united, the shells resting upon their 

 edges, and packed close to each other, exactly in the manner 

 that we might expect to have found them, supposing them to 

 have been recent shells with the animals yet inhabiting them. 

 Comparatively very few are gaping, and their condition and 

 position strikingly impress upon the mind the idea that when 

 alive, they must have inhabited the spot from which they are 

 now disinterred; especially as there are numerous small and 

 fragile species of other well-known London-clay shells, which 

 could not have remained whole had they been subjected to 

 much attrition amid the larger shells siuTounding them. On 

 the sands in the vicinity of this spot I found large masses of 

 Nummularia Icevigata cemented together, and numerous de- 

 tached specimens of the same shell. 



At the eastern extremity of this bed, which, at the time of 



