212 Geological Notes ona Recent Sewer Section at Park Hill Rise. 
seemed rather as if the latter were the more superficial layers 
of the clay which had changed colour owing to a process of 
weathering and unequal oxidation of the contained iron and 
manganese. 
The outcrop of this clay on the surface had a breadth of only 
11 yards, and its exposed thickness was about 23 ft. : 
G. Shelly Sand.—The last bed met with in the course of the 
excavation rested upon the mottled clay, and was of a sandy 
nature, varying from a coarse shelly sand containing numerous 
small rounded pebbles—in fact, almost a pebble gravel—to a 
yellow loamy sand with partings of blue clay, not unlike the 
sand met with below the pebble bed in the lower part of Park 
Hill Rise, except that while the latter contained no fossils, this 
bed was full of shells, chiefly fragmentary, though some very 
well preserved specimens of the round oyster (Ostrea bellovacina) 
were met with, this being the most abundant species. There 
were also a few specimens of the long oyster (Ostrea tenera), and 
of Cyrena and Melania, and some fragments of oyster were 
covered with Serpula. 
This bed may, I think, be classed as Oldhaven, and probably 
if the section had been prolonged to the south-east it would have 
been found to pass under the pebble gravel, which is exposed in 
the railway cutting a little further on in that direction, though 
it does not exactly resemble the beds found immediately under 
the pebble gravel, either in the lower part of Park Hill Rise, or 
in the railway cutting. The difficulty in correlating the beds 
exposed in the two sections is partly due to their having been 
cut across in different directions, but especially to their vari- 
able character, corresponding beds undergoing great changes in 
character and thickness in a short distance. This variability is 
accounted for by their having been formed on the shifting shore 
of a shallow sea or estuary. 
Postscript, February, 1897. 
Since this paper was read, some other excavations in the 
neighbourhood have given further opportunities for studying the 
relations of the beds. 
The clay bed D in the paper I now believe to be probably an 
outlier of the London Clay, which owes its preservation from 
denudation to its having been let down by the fault described. 
In a trench for the drain of the house Chichester Lodge, next 
on the north-west side of the position of the fault, this clay bed, 
where undisturbed, was 6 ft. thick above the pebble gravel, and 
was a dense brown clay, quite of the usual character of the 
London Clay. Mr. Whitaker also tells me that he has seen the 
London Clay exposed in a corresponding position in a sewer 
