Geoscience Reference
In-Depth Information
The presence of Chalk near the surface in Southern England is almost always
linked to the presence of hills and slopes in the scenery, clearly showing that Chalk
is a tough material that resists landscape erosion more than most of the other rock
types available. The Chalk is also noteworthy because it represents the most recent
time when most of Southern England was covered uniformly with soft sediment and
a shallow sea: in Late Cretaceous times, except for possible islands in the southwest,
there was no emergent land across Southern England.
Like all sedimentary bedrock layers, the Chalk initially formed as flat layers or
sheets of sediment, extending widely across the floor of the sea. As will be discussed
in the next chapter, these sheets of sediment are generally characteristic of stretching
movement episodes in the Earth's surface. Such movements produce areas of collapsed
and low-lying land that can accommodate large volumes of sediment, if it is available.
FIG
8.
Generalised succession of the bedrock of Southern England, showing a typical
thickness for each layer.
FIG
9.
The Chalk and its topography. The darker areas represent the chalk uplands.
However, we do not see the Chalk at or near the surface everywhere across South-
ern England; instead the Chalk forms narrow bands across the land. This is due to later
