Geoscience Reference
In-Depth Information
FIG
308.
Grimes Graves (Fig. 294,
c8
), 4 km northeast of Brandon. (Copyright Skyscan
Balloon Photography, English Heritage Photo Library)
A gravel quarry near Lynford (
c8
) has revealed, in recent years, a vivid picture of
life some 60,000 years ago on the floodplain of the ancestral River Wissey. At that time
the Devensian cold episode of the Ice Age was in full force, and local January/February
temperatures are estimated to have averaged -10°C or lower. Neanderthal man lived in
the area and it appears that they used an abandoned river channel loop as a location for
shepherding, trapping and butchering of mammoths, woolly rhinos, horses and bison.
Thetford has grown around a crossing of the westward-flowing Little Ouse, just
below the point where it is joined by the River Thet. An ancient road here, known as
the Icknield Way, followed a belt of open country marking the western edge of the
Chalk bedrock and our Landscape
C
. Thetford embarked on a programme of major
expansion in the 1960s, with the construction of large areas of housing and industrial
development, often in conjunction with London housing authorities.
The Wensum and Yare form the longest river in the Norfolk area (Fig. 291). It
is probably the latest version of a much longer easterly-flowing river that developed
when the bedrock of the area first began to tilt eastwards. Near Fakenham, the headwa-
ters of the Wensum lie in an area of very gentle hills ranging in elevation between 50
and 80 m above sea level. Much of this rather flat area is underlain by ice-laid material,
and the Wensum has cut a small, open valley into this with only a narrow floodplain
and a limited valley floor. Beside the river are patches of gravel moved from the local
slopes when spring floods were more vigorous, probably during and immediately after
the Devensian glacial.
Further downstream towards Norwich (
c10
) the river increases in size as it gathers
water from its branches and gradually drops in altitude. The locality map (Fig. 294)
shows how it develops a series of meanders downstream of Norwich, approximately
2-3 km from bend to bend. Gravel pits close to the Yare provide further evidence that
the river carried much coarser materials under the vigorous flooding conditions follow-
ing the Devensian glacial. In this area the whole shape of the valley (slopes and floor)
has a meandering form cut into Anglian ice-laid material, Late Tertiary Crag and Late
