Geoscience Reference
In-Depth Information
Landscape C: The Dorset Heaths
This Landscape passes westwards into Landscape
G
of Area 4. In Area 5, it is covered
largely by Poole Harbour and the City of Bournemouth, so its typical heath landscape
is only developed over rather small areas, where the Early Tertiary sandstones pro-
duce acid-soil vegetation. Although the landscape here is very subdued, there are small
hilly features created by erosion of the varying materials in the bedrock, or by unsteady
erosion of the rivers Stour, Avon and their tributaries. In fact, the southern part of this
Landscape is covered with many levels of unconsolidated surface materials, consisting
mainly of gravels brought down by ancestral versions of the rivers draining the Chalk
terrain to the north.
Just on the western edge of Area 5, below this young spread of Early Tertiary and
Quaternary sediment, is the Wytch Farm oil field (
c1
), the largest oil field in Europe
that has been drilled from land. The field was developed by BP and taps porous New
Red Sandstones of Triassic age which have been tilted and faulted into a valuable reser-
voir pattern. The oil itself appears to have come from Jurassic source sediments.
Landscape D: The New Forest
The New Forest became the newest National Park in Britain when an official Park
Authority was designated in April 2005. It occupies the distinctive part of the Hamp-
shire Basin between the Hampshire Avon to the west and Southampton Water and the
River Test to the east.
The New Forest has had special status for over 1,000 years, initially as a royal
hunting ground. The grazing and hunting of deer were particularly favoured by the bal-
ance of open and mixed woodland cover, resulting from the generally acid soils that
have formed on the Tertiary bedrock and the younger cover of Quaternary sediments,
particularly gravels. To maintain the mix of open ground and woodland cover, grazing
by ponies, donkeys, cattle and pigs has been actively encouraged for centuries by laws
defining the rights of local Commoners. At the same time, large-scale settlement has
been discouraged.
Detailed mapping of the Early Tertiary bedrock and the surface blanket of the
area has shown that the bedrock here has only loosely controlled the gently hilly topo-
graphy. One of the most obvious patterns is visible in the area east of Fordingbridge
(
d1
), where distinct ridges and valleys have been carved into the Early Tertiary strata,
draining southwestwards into the Hampshire River Avon. The ridges are capped by
what were, at one stage, defined as the 'Plateau Gravels', though these are now re-
garded simply as the earliest of a very large number of river terraces that are preserved
