PROCEEDINGS OF GEOLOGICAL SOCIETIES. 
59 
at Counter Hill (New Cross), Loam Pit Hill (Lewishatn), and very many- 
other places. 
The great shingle-beds of the neighbourhood of Bromley and Black- 
heath, have been in part classed by Mr. Prestwieh, though doubtfully, 
vrith the "basement-bed" of the London Clay ; but there is some reason 
to think that they may all belong rather to the Woolwich beds. In somo 
places, and markedly in the " rock-pit " in Sundericlge Park, near Bromley, 
and in the railway-cutting at Beckenham, there are fossils in the pebble- 
beds ; and it seems strange that many very delicate shells should be pre- 
served in a loose mass of hard pebbles. 
In some places, as on the hill above Abbey Wood, the shell-beds have 
thinned out, and there is nothing but sand and pebbles from the top to the 
bottom of the formation. The pebble-beds, as might be expected of de- 
posits of that nature, are merely lenticular masses on a large scale, of great 
thickness at one spot and near by altogether absent. 
Eastward of the valley of the Cray, Tertiary formations have suffered 
much from denudation, and from Dartford to beyond Gravesend are pre- 
sent only in the form of outliers. The clay shell-beds get thinner, and at 
the great section on the bank of the Medway, at Upnor, are only 6 feet 
thick, the sand above, however, also containing shells, but not that below. 
For some way east of Rochester this formation has been almost wholly 
denuded, but it comes on again west of Sittingbourne. Near this latter 
place the estuarine shell-beds thin out and are not seen further eastward. 
The pebble-bed at the bottom is also lost, and it is then difficult to draw 
the line between the Woolwich beds and the underlying Tlianet Sand, the 
former, however, being mostly a coarser and sharper sand, with here and 
there a few pebbles. The fossils also of the two formations are more alike, 
those of the Woolwich beds being here of a purely marine kind, and in 
great part of the same species as those of the lower formation, but of rarer 
occurrence. The sands tiiat in East Kent represent the AVoolwich beds 
are 25 to 40 feet thick, and are well shown on the coast west of the Eecul- 
vers, in sections near Canterbury and Ash, and in the railway-cutting at 
Richborough Castle. 
3. The Basement Bed of London Clay consists, near Lewisham and 
Bromley, of a more or less clayey pebble-bed, from 3 inches to 2 or 3 feet 
thick, and is well shown in the large pits at Loam Pit Hill, near the former 
place. 
Mr. Prestwieh classes with this bed, though somewhat doubtfully, the 
thick wide-spread mass of shingle of Blackheath, Charlton, etc.; but in 
the railway-cutting, east of Bickley, a sandy pebble-bed, like that of Black- 
heath, is seen to be overlaid by the usual clayey pebble-bed at the bottom 
of the London Clay, and it would seem therefore that the thick mass of 
pebbles in sand at Blackheath, etc., do not belong to this bed ; whether 
they belong to the underlying Woolwich beds or not, is another question. 
From this western part of Kent there are no sections of the " basement- 
bed " for some distance eastward, and possibly it may have thinned out. 
At Upnor, near Rochester, however, the whole of the Tertiary beds, from 
the lower part of the London Clay to the top of the Chalk, are shown. The 
former is underlaid by some 4 or 5 feet of fine light-coloured sands with 
shells, in a very friable state, and with pebbles near the bottom. These 
Mr. Prestwieh classes with the " basement-bed," and they certainly seem 
to be separable from the underlying sands and shell-beds of the Woolwich 
series, though, on the other hand, they are sharply divided structurally 
from the stiff London Clay above The fossils in them are, for the most 
part, of species generally found in the basement-bed (chiefly of the 
