The sand and gravel resources of the country around Whittlesey, Cambridgeshire : description of 1:25,000 resource sheets TF 20 and TL 29

The geological maps of the Institute of Geological
Sciences, pre-existing borehole information, and 186
boreholes drilled for the Industrial Minerals Assessment
Unit form the basis of the assessment of the sand and
gravel resources of the country around Whittlesey,
Cambridgeshire.
All the deposits in the resource sheet area that might be potentially workable for sand and gravel have been
investigated and a simple statistical method has been used
to estimate the volume.
The accompanying 1:25 000 map is divided into nine
main resource blocks. The geology of the deposits is
described and the mineral-bearing areas within each block
are distinguished by sub-blocks. The mean thicknesses of
overburden and mineral and the mean gradings, together
with detailed borehole data, are also given. The geological
lines and symbols, the positions of all non-confidential
boreholes used in the assessment (and grading information
for most IMAU boreholes) and the outlines of the resource
blocks and sub-blocks are shown on the accompanying
Map.
The principal mineral resources are First Terrace
fluviatile gravels (up to 8.2 m thick) and their
marine/estuarine facies; boreholes indicate that the latter
is more extensive than hitherto known. The thickness of
the overburden in the central part of the resource sheet
area increases towards the east and south and in the
northern part towards the north-east.
The survey supports a twofold altimetric subdivision of the 'Fen Gravel' and indicates that those gravels which
are equated with the Nene Second Terrace represent a
continuation westwards of the March Gravels.
The drilling occasionally encountered a 'leaf' of the
Lower Peat and indicated an eastwards extension of the
Tinwell-Marholm Fault.