210 Dr. H. F. Parsons, Geological Notes on-a 
and even somewhat beyond Chepstow Road, the bed consisted of 
incoherent gravel and sand, some of the pebbles, as already said, 
being very large, up to 9 by 5 in.; and it was here devoid of 
fossils. But higher up the Rise, where the pebble bed attained 
a greater thickness, the lower part of it was compacted by 
calcareous matter into a conglomerate bed, which at one place 
attained a thickness of 5 ft. This calcareous matter was 
doubtless derived from shells; chiefly the large round oyster 
(Ostrea bellovacina), of which many blocks of conglomerate were 
full. In some blocks the shell matter had been more or less 
completely dissolved away, leaving only impressions or casts 
with a thin layer of shell substance adhering. Masses of brown 
calcareous sandstone, enclosing a few scattered pebbles, were 
also met with, containing the same oyster and a few other fossils. 
The oysters evidently lived on the pebble bank, as is shown by 
_ the unworn condition of the shells, and by their having often 
attached themselves to the pebbles; and therefore the view that 
the oyster-bed was suddenly destroyed by an irruption of pebbles 
can hardly be correct, though the gradual accumulation of 
pebbles seems to have been inimical to the oysters, for none are 
found in the higher part of the bed. 
C. Sand.—Below the pebble bed in the lower part of Park 
Hill Rise is a bed of light yellowish loamy sand, containing 
harder lumps of a ferruginous colour, and thin laminated bands 
of blue plastic clay. No fossils were found in it. This sandy 
bed was just reached in the bottom of the trench at the Addis- 
combe Road end; it attained its maximum exposed thickness 
near the Chepstow Road, where it occupied the greater part of 
the depth of the trench; but higher up the hill it disappeared 
in the bottom of the trench beneath the thickened pebble 
bed. This bed may be classified as Oldhaven, and it may 
correspond with the yellow and grey sand with non-continuous 
partings of impure pipe-clay found beneath the pebble bed at 
Shirley, as described by Mr. Klaassen in 1890 in the Proceedings 
of the Geologists’ Association, vol. xi. No. 8. 
D. Clay.—In the upper part of Park Hill Rise the pebble bed 
is overlaid by a bed of brownish loamy clay, increasing in 
thickness towards the south-east, so that the pebble bed was 
met with in the sewer trench at greater and greater depths. 
This clay bed had been much disturbed by brickmaking opera- 
tions, broken bricks and a plank edged with hoop-iron, such as 
is used for wheeling on, were found embedded in it. The 
Ordnance Survey map, made 1868, shows a brickfield at this 
spot, and I am told that the houses in this part of Park Hill 
Rise were built with bricks made there. A crystal of selenite 
was shown me by a workman, which was said to have been 
found in this clay, but I do not know in what position. No 
