Geoscience Reference
In-Depth Information
Between Haverhill, Newmarket and Bury St Edmunds, the Chalk hills reach their
greatest elevations in Area 14 at about 120 m above sea level. South and east of New-
market (
b3
), north-facing scarps are the result of hard bands in the Chalk resisting
erosion. In the rest of this higher area of the Chalk hills, the slopes are the sides of
valleys carved in the surface blanket of Anglian ice-laid material, and so must have
formed during the last half-million years since that glaciation.
The town of Bury St Edmunds was laid out in the early 1100s around the precinct
of the great Abbey Church and shrine to St Edmund, which owes its location to the
River Lark (Fig. 249) and stands on a terrace with a gentle slope facing the floodplain
of the river.
In contrast to the Lark, most of the seaward-draining valleys in the Chalk hills
landscape flow generally towards the southeast, but some show distinct doglegs, which
seem to parallel the mapped boundary with the Early Tertiary landscape (Landscape
C
) to the south (Fig. 246). These doglegs may have formed when the downward-erod-
ing rivers met changes of erosional strength at the boundary between the Early Tertiary
bedrock and the underlying Chalk. As the landscape subsequently eroded downwards,
the valleys may have maintained their dogleg plan, following the boundary between
bedrock units by moving several kilometres southwards, down the gentle tilt of the
bedrock layers.
FIG
249.
The Abbey precinct in Bury St Edmunds (Fig. 247,
b4
). The River Lark flows
just in front of the red-roofed building. In the lower right corner is St Edmundsbury
Cathedral, to which a magnificent Millennium tower has been added since the photo-
graph was taken. (Copyright Aerofilms)
