Geoscience Reference
In-Depth Information
extending from the North York Moors, across the East Midlands and East Anglia, to
the Cotswolds, Hampshire, Dorset and the South Coast. Most of the marine sediments
are mudstones, but there are limestones of mid-Jurassic age that are particularly im-
portant in terms of the scenery. When these limestones were later uplifted and eroded,
they proved to be more resistant than the mudstones and so have produced distinct-
ive limestone topography. It is also because of their toughness that these Middle Jur-
assic limestones became a common building material in the west of this Region, from
Northampton towards Peterborough and up to Grantham. This building stone gives vil-
lages and towns an attractive appearance that is better known further southwest, in and
around the Cotswold Hills. The Late Jurassic mudstones have also proved to be nation-
ally important as sources of oil and materials for brick-making.
FIG
227.
The land and sea pattern during the Middle Jurassic, with Areas 13-16 out-
lined.
Early Cretaceous sediments were again largely limited in their deposition to a gulf
similar in its position to the Jurassic gulf, though there were episodes of no sediment-
ation and sedimentation by streams and rivers rather than the sea. The thickness of the
sands deposited varies from place to place, as represented by the present bedrock of the
Lower Greensand (very obvious in Bedfordshire), and the Carstone (in West Norfolk),
but the variations still involved very low slopes. Subsequent erosion has picked out the
relative strength of these sandstones enough to form local hill features. In some areas
the sandstones have been valued as local building stones, particularly where they have
