Geoscience Reference
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FIG 107. Slope (greater than 3 degrees) and hillshade map of the Hampshire Basin.
Located on Figure 100.
The Dorset Downs are a classic area for studying features of Chalk scenery. The
typical rolling, grass-covered tops and the steep-sided valleys, sometimes with flat bot-
toms, show up beautifully on the slope map in Figure 107. Many small valleys and
hollows in the faces of the Chalk hills are dry, having been formed by slope failure and
stream flow during the Ice Age when the subsurface was frozen (see the general intro-
duction to this chapter for more detail).
The present drainage of this Landscape takes place to the east and south, towards
the centre of the Hampshire Basin. Major rivers are the Frome, through Dorchester,
and the Stour, which cuts through the Downs at Blandford Forum ( f1 ).
Landscape G: The Dorset Heaths
This Landscape, lying between the Dorset Downs and the Purbeck Chalk ridge, is un-
derlain by flat-lying bedrock of Early Tertiary age. This bedrock occurs in a shallow
basin centred on Poole Harbour that also contains the large conurbation of Poole and
Bournemouth (see Area 5).
Although there are layers in the Early Tertiary succession that are assigned to the
London Clay, other layers below and above this are more prominent and much richer
in sand. This gives rise to the widespread acid-soil heathland with a vegetation cov-
er of heather, bracken and gorse, though much of this habitat has now been converted
to farmland or conifer woodland. The hills and slopes of the area are low and poorly
defined, sometimes marking sandy layers in the Early Tertiary bedrock. There are also
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