The sand and gravel resources of the country west of Darlington, County Durham : description of 1:25,000 resource sheet NZ 11 and 21

The geological maps of the Institute of Geological
Sciences, pre-existing borehole information, exposures
and 41 boreholes drilled for the Industrial Minerals
Assessment Unit, form the basis of the assessment of
sand and gravel resources of an area in N ort~
Yorkshire and County Durham, west of Darlington.
All deposits in the area which might be potentially
workable for sand and gravel have been investigated
and a simple statistical method has been used to
estimate the volume. The reliability of the volume
estimates is given at the symmetrical 95 per cent
probability level.
The 1 :25 000 map is divided into three resource
blocks containing respectively 5.3, 9.2 and 9.9 km2 of
potentially workable sand and gravel. For the blocks
assessed statistically the geology of the deposits 1s
described and the mineral-bearing area, the mean
thickness of overburden, mineral and waste and the
mean grading of the mineral are stated. Detailed
borehole data are given. The geology, the pos1t1on of
the boreholes and the outlines of the resource blocks
are shown on the accompanying map.