Geoscience Reference
In-Depth Information
The present development plan for the Fen involves the enlargement of the reserve to
include some surrounding farmland, which will then be allowed to revert to natural wet
land, acting as a recreational 'green lung' for the highly developed Cambridge area.
Before the engineered drainage of the Fens, more-or-less permanent lakes were
local features, particularly around the edges of the Fenland, where groundwater tends
to flow from the neighbouring uplands. Soham Mere was a good example of one of
these lakes, and the outline of the drained lake is still clearly visible in aerial photo-
graphs (Fig. 243). The extent of the former mere is now marked by a patch of lighter
soil that contrasts strongly with the surrounding fields of darker peaty soils. The light-
ness is the result of chalk-like limey deposits made by single-celled plants that lived
in the lake. The plants made use of the 'hard' water which emerged as springs through
the limestone and chalk of the surrounding uplands, producing calcium carbonate that
then collected on the bottom of the lake as the plants died and sank.
AREA 14: SUFFOLK AND NORTH ESSEX
In the general introduction to the East Anglian Region, I stressed the open feel of the
scenery and the absence of high hills, explaining these to be the result of the unusual
lack of movement of the Earth's surface in this Region over the last 300 million years.
Other results of this lack of movement are that the bedrock succession formed during
this time varies only slightly across the Region, so that a single, generalised bedrock
succession (Fig. 225) is adequate to represent the bedrock pattern across all four Areas
of the Region (Fig. 226), and the bedrock layers have a very gentle tilt and simple pat-
tern.
The scenery of Area 14 (Figs 244 and 245) is largely the result of relatively recent
river and coastal processes acting upon earlier landscapes. In broad terms, the valleys
of the Area consist of a small northwesterly-flowing group draining to the Fenland
coastal zone, and a more extensive southeasterly group draining towards the coasts of
north Essex and Suffolk (Fig. 246). These rivers have fairly small catchments, with
their headwaters in the nearby Chalk hills, an area which receives relatively little rain-
fall compared to other areas of Southern England. Consequently the mean flow rates
for these rivers are rather small.
