covered by cream-coloured calcareous stone disposed in very thin undulated laminæ, and locally termed "soft burr;" and above are shales, and thin bands of limestone, belonging to the lowermost beds of the Purbeck.

There are also layers of chert containing chalcedonic casts of freshwater shells, in the cliff just above the sea level.*

DURDLE, OR BARN-DOOR COVE.-There are several smaller bays, which are worth examining if the visitor's leisure will permit: these are Mupe Cove, which is situated in Worbarrow Bay (see lign. 31, p. 269); Stare Cove,+ near Lulworth; and Man-of-War Cove, half a mile further to the west, so called from a long rock at the entrance, named the Man-of-War. In each of these bays the same geological phenomena are observable. They may all be approached from the land, but are seen and studied to most advantage from the water.

Durdle, or Barn-door Cove, is remarkable for a natural perforation or archway, formed by the waves in a projecting crag of the nearly vertical Portland oolite, which bounds the eastern cape of the bay. This arch, commonly called the Barn-door, is large enough to admit the passage of a boat with the sails up; and in very fine weather it is customary for the pleasure parties from Weymouth to sail through it. The western cape of the bay is composed of vertical strata of chalk and flint, and is called Bat's Corner. (See lign. 31, p. 269). This bay, therefore, differs from those above described, in presenting but one section of the

*On the hills near Lulworth there are detached blocks of the Hertfordshire siliceous pudding-stone lying upon the chalk; and large masses of this conglomerate may be seen in the street of West Lulworth, and in the walls of some of the cottages.

† Stare Cove-so called from several caverns through which the sea dashes with a loud roar. In this cove the contortions of the Purbeck beds are very grotesque and remarkable. Pl. xliv. of Mr. Webster is a fine view of this little bay.

strata, which, commencing with the chalk on the west, and succeeded by the lower groups, terminates in the Portland oolite on the east. The view by Mr. Webster (see Pl. XIX.) admirably illustrates the geological structure of this beautiful bay. In this sketch the chalk appears on the right, forming the high cliff on the western cape, termed Bat's Corner; in passing thence, the firestone, galt, Wealden, and Purbeck strata, successively appear, and lastly the Portland rocks, which terminate the point on the left of the view, as indicated by the archway called the "Barn-door." A line of low oolitic rocks stretches across the mouth of the bay.

CHALDON DOWNS.-Proceeding to the westward we lose all traces of the beds below the chalk; the chalk cliffs, which are between 200 and 300 feet high, form the western headland of Durdle Cove, and continue along the coast to Whitenore Point, the eastern cape of Weymouth Bay, a distance of about two miles (lign. 36,); these strata present some interesting features. In these cliffs, the gradual transition of the chalk beds from a vertical to a gently

LIGN. 36. CHALK CLIFFS, ON THE SOUTH-WEST COAST OF THE ISLE OF PURBECK FROM BAT'S CORNER TO WHITENORE POINT.

(The Rev. W. D. Conybeare.)*

inclined position, is clearly shown.

The vertical strata

at Bat's Corner, partake of the same characters as those at Handfast Point; the chalk being much indurated, and the flints shattered. A quarter of a mile to the west the layers of flint are nearly horizontal, being united with

* "Geology of England and Wales."

the vertical by a gentle curve, as shown in lign. 36; and in these beds the chalk possesses its original friable texture, and the flints are entire. Towards Whitenore the firestone and galt appear at the base of the cliffs. At this spot the chalk trends inland, and thence to Weymouth the coast is flanked by cliffs and flat shores of the inferior strata. From the summit of the chalk cliff at Whitenore, which is about eight miles E.N.E, of Weymouth, the view to the west shows numerous little bays, hollowed out of the shore by the action of the sea along the coast, as far as Weymouth, and Portland island is strongly defined on the horizon over the sea. To the eastward are seen the chalk cliffs extending to Bat's Corner, and the projecting capes of Durdle and Lulworth Coves, and the summit of Worbarrow Down.

RINGSTEAD BAY.-To the west of Whitenore, the Kimmeridge clay, which we lost sight of at Gad Cliff (see p. 264), re-appears in Ringstead Bay, and a good section of the strata is exposed in the cliff. Proceeding towards Weymouth, the clays in the lower part of the series gradually become sandy and calcareous, and pass insensibly into the Oxford oolite.

In Ringstead Bay, there is a striking example of that kind of displacement, which is geologically termed a fault; signifying a vertical or diagonal fissure through the strata, accompanied either by a subsidence, or an upheaval, of one side of the dislocated masses. In this instance the beds, consisting of chalk, firestone, and oolite, on the south side of the fissure, are thrown down much lower than those from which they have been separated. This phenomenon is connected with the displacements which the districts we have passed over have undergone. The line of disturbance we traced through the Isle of Wight, forming the anticlinal axis from east to west, continues through the Isle of Purbeck from Swanage Bay to Lulworth Cove and the adjacent bays, and is prolonged westward through the