ter the
Chalk outcrop narrows and turns south-eastward by Portisham, Bincombe,
to West Lulworth, thence the crop proceeds eastward as the ridge of
the Purbeck Hills, and finally runs out to sea as the headland between
Studland and Swanage Bays.

Upon the Chalk in the eastern part of the county are the Eocene beds
of the Hampshire Basin. These are fringed by the Reading Beds and
London Clay, which occur as a narrow belt from Cranborne through
Wimborne Minster, near Bere Regis and Piddletown; here the crop swings
round south-eastward through West Knighton, Winfrith and Lulworth, and
thence along the northern side of the Purbeck Hills to Studland. Most
of the remaining Eocene area is occupied by the sands, gravel and clay
of the Bagshot series. The Agglestone Rock near Studland is a hard
mass of the Bagshot formation; certain clays in the same series in the
Wareham district have a world-wide reputation for pottery purposes;
since they are exported from Poole Harbour they are often known as
"Poole Clay." From beneath the Chalk the Selbornian or Gault and Upper
Greensand crops out as a narrow, irregular band. The Gault clay is
only distinguishable in the northern and southern districts. Here and
there the Greensand forms prominent hills, as that on which the town
of Shaftesbury stands. The Upper Greensand appears again as outliers
farther west, forming the high ground above Lyme Regis, Golden Cap,
and Pillesden and Lewesden Pens. The Lower Greensand crops out on the
south side of the Purbeck Hills and may be seen at Punfield Cove and
Worbarrow Bay, but this formation thins out towards the west. By the
action of the agencies of denudation upon the faulted anticline of the
Isle of Purbeck, the Wealden beds are brought to light in the vale
between Lulworth and Swanage; a similar cause has accounted for their
appearance at East Chaldon. South of the strip of Weald Clay is an
elevated plateau consisting of Purbeck Beds which rest upon Portland
Stone and Portland Sand. Cropping out from beneath the Portland beds
is the Kimmeridge Clay with so-called "Coal" bands, which forms the
lower platform near the village of that name.

The Middle Purbeck building stone and Upper Purbeck _Paludina_ marble
have been extensively quarried in the Isle of Purbeck. An interesting
feature in the Lower Purbeck is the "Dirt bed," the remains of a
Jurassic forest, which may be see