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BGS Technical Report WA/97/03 1.5 December 1997
communication 1996).
The dominant faults of the area are mostly post-Triassic reactivations of Variscan structures. The
main fault is the northern continuation of the Needwood Fault (=Hints Fault; Barclay, 1997); its
course in the present area is largely conjectural.
6.1 Strata1 dip
There are a few measurements of dip recorded within the strata of the area. One problem with
all the dip readings is the effect of ice-heave and cryogenic disruption of the strata. In the north
of the area near Dalbury [2652 34701 the strata dip gently to the south-south-east, a direction
which accords with the strike of the sandstone unit within the Gunthorpe Formation north of
Highfields Farm [2700 34071. This strike is also suggested fiom the outcrop pattern of the
Cotgrave Member both to the north [2867 33541 and south [2965 31761. In the south of the area
a few dips were measured along the Derby Southern Bypass. To the east of Tynefield Court
E2690 30721 the strata dip about 5 degrees to the east-north-east; three hundred metres to the
west-north-west [2660 30801 the dip is about 5 degrees to the west. A minor anticline is
suggested by the dips, it may possibly be related to the northerly-trending fault located about 600
m farther west. West of this fault more variable dips have been recorded in the borrow pit for the
new road scheme. At the east of this pit [2573 3 1551 the dip was recorded as 4 degrees to the
south, west of the pit [2560 3 1531 the dip was 1 1 degrees to the west-south-west. These variable
dips in close proximity may relate to the nearby faulting.
6.2 Faults
'
The faults within the area are mainly postulated fiom very scant surface geological information
and deep seismic data (interpreted by T C Pharaoh, oral communication 1996). The deep seismic
data images the base of the Triassic sequence and the structure in the underlying Carboniferous
rocks, but gives very little detail for the Triassic sequence itself. As a consequence many faults
are extrapolated fiorn the base of the Trias to the surface. It is noted that the seismic data gives
little indication of the trend of the faulting, which can only be inferred where they cut more than
one seismic line.
The north-trending Needwood Fault, which throws to the west, lies along the western side of the
area and is structurally related to the eastern margin of the Triassic Needwood Basin. The fault
is proved in a seismic traverse just south of the area and is further suggested by borehole data
there.
In the northern part of the area, an approximately east-west trending fault is suggested fiom one
seismic line near The Cottage [2770 341 11. The westerly continuation of the fault is indicated
by the truncation of the sandstone unit that passes about 500 m west of The Cottage. The easterly
extension of the fault is suggested by a slight off-set of the Cotgrave Member near Bonehill Farm
[2721 34171.
A fault with a north-east to south-west trend passes through the central part of the area just to the
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