WELLS ON FOWLNESS ISLAND;
123
structure would alone distinguish it. Were it composed of
separate flints, what reason would exist for mention apart from
the rest of the deposit, of like character ? I am disposed to
include the eighteen inches in both cases with the London Clay,
just as the bed of green-coated flints at the base of the Tertiaries,
being the residual product of subterranean dissolution of the
chalk surface, and not of Tertiary deposition, should be
accounted a part of the Cretaceous.
Although the site under consideration was in the later stages
of the deposition of the alluvium in the bed of a creek, the floor
at an earlier stage was 17ft. 6in. higher than that at Old Hall,
Church End. Whether the one is on a concealed shoal, or the
other in an obliterated channel, this difference of level, propor-
tionally vast in a region where gradients are measured by inches,
is presumably the reason of the presence of but mere traces of
gravel or shingle, and in the lower 5 feet only, at the shallower
position, as compared with 31 feet 6 inches of clean shingle at
the deeper. That the shallower had lumps of clay intermingled
with the gravel and sand in the said 5 feet indicates that erosion
of the clay was in progress at no distant point, possibly of a now
vanished islet. Then, above this irregular mixture, between
sands whose green tint denotes organic matter copious enough
to prevent peroxidation of the iron present, occur two bands of
stiff yellow clay with streaks of sand, pointing to a more com-
plete disintegration of the parent mass of clay, probably now
more remote. The deeper site meanwhile received, or rather
retained, nothing but clean sand, all suspended clay passing
seaward.
The section of the well of 1886 at Old Hall, constituting the
third of the documents under notice, is a drawing on the scale of
16 feet to the inch, with figured thicknesses or depths of the
beds distinguished by the drillers, and of the several strings of
concrete and iron tubing with which the borehole is lined.
The location and date are omitted, but Mr. Hall kindly furnished
the former, and for the date I find that in June, 1886, I wrote to
the. late Mr. C. Harvey, referring to the commencement of
operations, and begging his assistance in securing a proper
record of the beds penetrated. My desire is fulfilled at this late
date, whether owing to my request or otherwise I know not.
He had some twenty years previously told me that the previous