3 
LONDON CLAY. 
Soil.-— Colour, Orange brown, Y. R B, % of Sowerby's Chromatic Scale, varying when wet. 
Consistence, Tenacious; free from Stone; dries clotty; cracks in drying; surface 
frequently covered with alluvial Pebbles. 
Subsoil and Ditches, Retentive. 
Excavations, Hold Water. 
Stratum, Dry, of a dun colour. Darker when wet. 
Water, Rarely any ; the little which it produces of a bad quality . 
THIS thick Stratum, from its being the site of the Metropolis, and most abundant in 
its environs, has been called the London, Clay. Its course north-eastward to the sea is 
described in the Map, by the same colour as the plate annexed. 
The greatest length, from S. W. to N. E. is in a line passing from Richmond, through 
London to Harwich. 
The greatest breadths, from Norwood Hill to Enfield Chase, and from Langdon Hills to the 
extremity of Epping Forest. It thence occupies the heights in the hundreds of Essex, and east 
of Chelmsford and Colchester ; extends through the Sokens to the sea side at Walton Nase, 
and Harwich. 
The soil is of a mellow brown or umber colour, and the subsoil generally the same, although 
the Stratum deeper (as lately shown by the tunnels under London,) is of the colour by which I 
have endeavoured to represent it. 
The exact boundaries of soft Strata are generally difficult to define, but particularly so in this 
district, where they alternate with no hard materials in the form of Rock. 
Outcrops also of such loose Strata, are too confused for the Geologist to avail himself of the 
distinctive advantages to be derived from their peculiar imbedded Fossils, as throughout the district 
over Chalk, they are found only in deep excavations. 
The shelly part of the London Clay bears but a small proportion to the thickness of the mass. 
The shells, therefore, should rather be considered as Indices to the site of that particular part, 
than to a knowledge of the whole. They lie near the bottom of the Stratum, and in some 
instances are difficult to be distinguished from those of the Crag, which accompanies the sand. 
ORGANIZED FOSSILS . 
FIG, 
1 Vivipara fluviorum - - Well at Brixton Causeway. Hordwell Cliff/ 
% Tellina, &c. -• - Sheppey. Happisburgln 
3 Area Linn. Pectunculus Lam . - Bognor 
4 Chama - - - ~ Hordwell Cliff. 
