Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/206

 Chalk, with flints in the top part ; at the bottom a thin fissile greenish layer (which also occurs on the coast eastwards).

Chalk-rock ; a layer of hard green nodules, the upper surface better marked than the lower.

Chalk without flints.

In a larger pit, at the kiln above Rollington, on the northern side of the range, and therefore in the higher part of the Chalk, there are but few flints.

The step -like outline of the top of the hills from Corfe Castle to Nine-Barrow Down has been noticed elsewhere *. Westward of the former place the range again rises by steps in a like manner, and is partly breached at the western end of Knowl Hill. Here there is a pit in Chalk with few flints, at the northern foot of the hill, whilst further south, and therefore lower down stratigraphically, another pit shows Chalk with layers of flints, and with a sort of slickenside- surfaces at right angles to the bedding. Still further south, the road- cutting up the slope southwards is in Chalk with flints ; but at the top of the rather low hill the flints seem to end, and as the road turns down again eastward the hard cream-coloured nodular Chalk-rock is shown, and below it Chalk without flints.

From this slight gap in the escarpment a longitudinal combe runs westward as far as Screech Barrow, making two ridges. Screech' Barrow itself is a conical Tertiary hill, close to and rising above the chalk-escarpment.

Signs of the Chalk-rock were again seen on the newly cut road above West Tyneham.

There are many small pits on the flank of the escarpment in the so-called Isle of Purbeck, showing Chalk Marl and Lower Chalk, but not high enough to touch the Chalk-rock. The Chalk is throughout rather hard.

Flower's Barrow, on the top of the ridge where it again meets the sea, is one of those instructive gauges of the loss of land by the sea that are often given us by the old earthworks. Nearly half of the entrenchment has been carried away, and the high cliff now cuts through its middle part. Here the top part of the Upper Greensand stands out, from its hardness. I could not see the Chalk-rock along the top of the cliff, nor could I get near enough to the foot in a boat ; but a bluish-grey clayey bed, some feet thick, could be made out at the top part of the Chalk Marl, as in the eastern coast-section. At the headland on the western side of Worbarrow Bay there is a natural arch at the foot of the cliff, through which small boats can go.

In Mewps Bay the following succession of beds may be seen along the shore : —

Upper Chalk.

Chalk with flints, running out to sea as a ledge, with a hollow and cave cut in the cliff.

Chalk without flints (?), about 15 feet.

the Lower Tertiary Beds.' Reprinted, with corrections &c., from the Geol. Mag. vol. iv.
 * ' On Subaerial Denudation and on Cliffs and Escarpments in the Chalk and