288 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jutie 1, 



as indicating the presence of a large pipe beneath them, and as known 

 to the workmen there by the name of "core." For about 15 yards 

 in the centre of the section, there is a bed from 1|^ to 2 feet thick of 

 laminated loam, in the midst of a mass of loosely aggregated gravel, 

 with little appearance of stratification. The gravel above this loam 

 is apparently much coarser than that below; which, however, is 

 much obscured by a talus. The eastern end of this loam, which 

 is thickest, is curved downwards, as is another smaller seam which 

 makes its appearance a little above and beyond it, and which ter- 

 minates against another "core," composed chiefly of an unstratified 

 mass of silty loam, but with gravel on the side having a rude vertical 

 stratification, and with coarse gravel above it. A little to the north, 

 there is a circular cavity in the chalk, which the workmen have 

 followed downwards for a few feet for the sake of the fine gravel 

 which it contains. This is composed almost wholly of small eocene 

 pebbles, but it is evident that they have been re-arranged, from the 

 presence of a few subangular flints and fragments of the cherty sand- 

 stone before mentioned. 



In an old gravel-pit at Sutton Place the greatest depth is about 

 15 feet, but there are several points at which peaks of chalk rise to 

 within 5 feet of the surface. 



At the cutting near the Dartford Station, rounded eocene pebbles 

 are the most numerous, mixed with unworn and partially abraded 

 flints, some of them of considerable size. With them are associated 

 in much smaller quantities other pebbles, which indicate transporta- 

 tion from the north and west. The most abundant of these are 

 pebbles of white quartz, and those peculiar quartzose pebbles which 

 form so large a portion of the gravel of the Midland Counties, formerly 

 described by the Dean of Westminster under the name of the War- 

 wickshire Gravel*. 



It will be remembered that Dr. Buckland traced these pebbles 

 from their source in a Triassic conglomerate, about Cannock Chase 

 and the Upper Lickey, to the base of the Cotteswolds, and through 

 depressions in that range to the high grounds bordering the Thames 

 in the neighbourhood of Oxford, and thence brought by denuding 

 action, then called by him the reflux of the diluvial wave, into the 

 valley of the Thames, as far as Hyde Park. 



With these quartzose pebbles I have found at Dartford several 

 fragments of those sandstones which I refer to the subcretaceous 

 rocks, one small pebble of granite, and a pebble of flinty slate, such 

 as accompany the quartzose pebbles in the Midland counties. I have 

 also found one flat angular piece of hornblende rock, which must be 

 considered as doubtful, since it was not actually imbedded, and may 

 have come from the surface and have been deposited there through 

 the instrumentality of the London manure cart. 



The gravel bed which rests on a ridge of chalk bounding the 

 valley of the Darent on the east, varies much in the mode of aggre- 

 gation through the length of the section exposed, which is about 

 ()00 yards. In some parts it consists chiefly of coarse sand, con- 

 * Trans. Geol. Soc. 1st Series, vol. v. p. 521. 



