Geoscience Reference
In-Depth Information
FIG
247.
Bedrock pattern, structure, Landscapes A to D and localities (
b1, b2
etc.) in
Area 14.
The tilt of the bedrock layers in this area is uniformly less than 1 degree to the
southeast; there is no measurable difference between the Late Jurassic and the Early
Cretaceous tilt, despite a time gap of some 16 million years. This implies an absence of
tilting movement during this period, before the formation of the thin (up to 20 m thick)
Lower Greensand and the thicker Gault. In scenery terms, the Lower Greensand has
often produced slightly higher ground than the mudstones below and above, demon-
strating its greater resistance as the landscape was being eroded.
Landscape B: The Chalk Hills (Late Cretaceous)
This Landscape is defined by the near-surface presence of Late Cretaceous Chalk. The
erosion of the Chalk hills is being carried out now by rivers flowing in two very dif-
ferent directions. In the north and northwest of Area 14, the River Lark drains north-
westwards towards the Fens (Area 15). However, the vast majority of the Chalk hills
are drained to the east coast by rivers such as the Waveney, Deben and Stour.
In the northwestern part of this Landscape, because of the southeasterly tilt of the
Chalk, the surface is underlain by the lowest layer of the Chalk, which has produced
