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BGS Technical Report WA/97/03 15 December 1997
corner of the sheet area and extends onto sheets SK 22 NE, SK 33 SW and SK 32 NW.
In tunnel valley situations, much of what has been determined as till in boreholes and poorly
exposed sections may in fact be very stony, unlaminated, glaciolacustrine clay.
Details:
Elvaston Palaeochannel
The channel is a prominent Quaternary feature on Sheet 141 (Loughborough). It has been traced
along a slightly sinuous, east - west course for about 19 km while maintaining a width of only
0.4 - 1 km. It first appears in the east a short distance to the east of the M1 crossing of the River
Trent [465 3 101 at Sawley (Brandon, 1996, figure 5). From there it follows the Derwent valley
and then crosses the DenvendTrent interfluve from Allenton to the Findern area (Brandon, 1996;
Brandon, 1997; Cooper, 1997) from where it deepens on entering the north-eastern corner of
Sheet SK 22 NE and the adjoining parts of Sheet 32 NW and SK 23 SE before closing.
Data on the channel infill deposits in the present area derive from boreholes and personal
observations during excavation of cuttings along the route of the Derby Southern Bypass, and
from confidential site investigation boreholes at the Toyota car factory.
In this area and the adjoining part of SK 22 NE, the stratigraphy of the infill deposits beneath a
partial cover of Etwall Sand and Gravel and Eagle Moor Sand and Gravel is fairly clear. The
major deposit is a glaciolacustrine unit, termed the Findern Clay (Section 5.1.2). This is generally
underlain by a relatively thin deposit of lower Oadby Till which rests directly on bedrock
(Figures 2 & 3). In places along the Bypass cutting, on sheets SK 23 SE and SK 22 NE, an upper
Oadby Till is preserved in large pods irregularly overlying the Findern Clay.
The lower Oadby Till is generally a stiff, compact, consolidated, dull brown, stony, clay/siltbased
diamict with a variable, but generally moderate, stone content. The stones include flint,
chalk, Bunter quartzite, coal and sandstones from the Mercia Mudstone Group. No sections in
the lower Oadby Till were seen during the survey of the Etwall area, nor was it penetrated by the
deeper boreholes connected with the bypass route (see Figures 2 & 3). It was proved on the
adjacent part of SK 22 NE and is probably present at the base of the palaeochannel in the present
area.
The upper till, exposed in the Derby Southern Bypass cutting [2902 29971 to the west of the A38,
comprised c. 1 m of slightly reddish brown-weathering, chalky till cryogenically involuted with
the overlying gravel of the Etwall Sand and Gravel. Logs of boreholes along this transect (Figure
2) indicate that up to 5 m of upper till may be present in pod-like bodies although, as stated
above, it is extremely difficult from the borehole logs to distinguish between Oadby Till and
Findern Clay with dropstones. The bypass sections would seem to indicate that Findern Clay
wraps around the upper till, at least in part. A section along the bypass E2852 301 1 to 2867 30061
was logged as follows:
12