1866.] WHITAKEE LOWER LONDON TEETIAEIES. 415 



AVoolwich species (Cyrena cuneiformis, C. cordata, Melania in- 

 quhiata, and Cerithium) ; "whilst in another, less than a mile off, 

 they are for the most part marine (Cardium, Pectunculus, Apor- 

 rhais, Ccdyptrcea, Fusus), but with a mixture of ^the freshwater 

 shells. 



But a little southwards from these pits another change takes 

 place, there being nothing but some 30 feet of pebble-beds over the 

 Woolwich sand at the outlier of Shottenden Hill, the only place in 

 East Kent where this part of the series thickens in the same way as 

 at Blackheath, Bromley, (fee. 



Westwards the pebble-bed is thin, and sometimes there are merely 

 a few pebbles in the bottom part of the Oldhaven sand ; but on the 

 Cobham hills it swells out again, and from Erith by Plumstead Com- 

 mon to Blackheath is very thick, as also on the south at Bromley and 

 Chiselhurst, the name of which last place, indeed, is derived from 

 the Saxon " Chesil," a pebble. 



From Blackheath to Lewisham, a distance of about a mile, the 

 pebble-beds thin away quickly ; and in the cutting on the Lewisham 

 and Tunbridge Hallway there was to be seen (in 1864) a layer (no 

 more than from a few inches to a foot thick) of pebbles in sand 

 capped by another (of the same thickness) of pebbles in clay, the 

 latter being the true basement-bed of the London Clay. 



Although this division of the Oldhaven Series has been here treated 

 as one bed, yet one cannot be sure that the w^hole of the thick mass 

 of pebbles of West Kent represents, or is the same as, the thin layer 

 of the eastern division of the county ; for it is possible that other 

 beds may come on above, and that the sand of East Kent may be 

 replaced westward by pebbles ; but I think that it is the safe and 

 right thing to treat of it so until the contrary view can be proved, 

 and the more so as here and there a layer of sand occurs above the 

 pebbles in the neighbourhood of London. 



Most observers must be struck with the very great extent to 

 which these pebbles have been worn. The flint-shingie of our coasts 

 nearly always contains flints in many states of wear, from the rough 

 piece that has not long fallen from the chalk-clifFs to the rounded peb- 

 ble ; but here cdl are finished ; at least it is very rarely indeed that even 

 anything like a subangular flint is to be seen. It would seem there- 

 fore that these old pebble-beds could hardly have been a shingle- 

 beach along a chalk shore, for in that case they ought to contain 

 many flints but partly worn. They must, however, have been de- 

 rived from the Chalk; and one is led to infer therefore that they 

 must have been deposited as a shingle-bank some way off shore, 

 to which no flints could get until they had been so long exposed to 

 the wearing action of the sea as to be well rounded. 



(y) In East Kent a fine light-buff sand forms nearly the whole 

 of the Oldhaven Beds, excepting at Shottenden Hill, where it is not 

 shown. Near Canterbury and the Eeculvers, this is from 15 to 20 

 feet thick, for the most part finely false-bedded, sometimes with 

 layers of clay or of sandstone, and sometimes with fossils. 



