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LIGN. 16. THE SECTION OF THE STRATA EXPOSED ON THE SOUTH COAST, FROM THE FOOT OF AFTON DOWN TO

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LIGN. 17.-CONTINUATION OF THE COAST SECTION FROM GRANGE CHINE TO ST. CATHERINE'S DOWN.

The distance about 5 miles.

(From Dr. Fitton's Memoir Geol. Trans. vol. iv. pl. x^.)

imbedded in the upper layers, and freshwater shells in the

lower portion.

PEBBLES AND SHINGLE.-Before we ascend the cliff to pursue our excursion towards Atherfield, I would offer a few remarks on the sea-beach.

The beds of shingle along this coast consist, in a great measure, of chalk flints that have been broken and rounded by attrition into boulders, pebbles, and gravel. This is evident from the peculiar aspect and fracture of the stones, and the nature of their organic remains, of which some traces are generally manifest. The clear, transparent pebbles, with bands and veins of quartz and chalcedony, which in some specimens are as clear as crystal, and in others of a bright yellow, amber, dark brown, and bluishblack colour, have a similar origin. The moss-agates,* as they are called by the lapidaries, are silicified chalk sponges; and the beautiful fossils (Choanites) † commonly known as petrified sea-anemones, are characteristic zoophytes of the white chalk. Small pebbles of pure transparent quartz or rock-crystal are often found in the shingle in Compton and Sandown: these have probably been washed out of the Wealden strata, for pebbles identical in mineralogical character occur in the grits of Tilgate Forest and Tunbridge Wells.

But the shingle contains other siliceous pebbles which essentially differ from those of the chalk-flints. Some of these are composed of a dark-brown mottled jasper, and when cut and polished resemble the well-known Egyptian pebbles; others are of an opaque white jasper, veined with black dendritical or arborescent figures, or marked with zones of rich brown tints. Some have a concentric arrangement of bands of silex of various shades of colour, and

* Not the German moss-agates exhibited in the shops as the genuine productions of the Island. See note to page 2.

"Thoughts on a Pebble," pl. 1 and 2.

PEBBLES AND SHINGLE.

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resemble agates; others assume the character of botroidal and mammillated chalcedony.

The differences observable in the materials composing the shingle, did not escape the notice of Mr. Webster, who describes some of the principal varieties of the pebbles, and suggests that those which are not waterworn chalk-flints may have been derived from veins or nodular masses of silex, in tertiary strata now destroyed. A polished slice of silicified wood found in the shingle of Sandown Bay, was presented to me by Mr. Fowlstone, of Ryde.

I believe specimens of this kind are very rare in the Island; but on the western coast of Sussex waterworn fragments of silicified monocotyledonous wood are occasionally met with.

Boulders and pebbles of petrified bone and wood, and of shelly limestone, are common on the beach in Compton and Sandown Bays; they are from the Wealden beds, and will be more particularly noticed in a subsequent chapter.

CHAPTER VIII.

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FROM COMPTON BAY TO ATHERFIELD POINT-ATHERFIELD CLIFFS -GREENSAND SERIES-NEOCOMIAN OR ATHERFIELD STRATAGREENSAND FOSSILS-CLIFFS AT BLACKGANG CHINE UNDERCLIFF-GEOLOGICAL STRUCTURE OF THE UNDERCLIFFFOSSILS OF THE FIRESTONE-SOUTHERN RANGE OF CHALK DOWNS COAST OF THE UNDERCLIFF-FROM VENTNOR TO SANDOWN BAY.

FROM COMPTON BAY TO ATHERFIELD POINT.-The road from Compton Chine to the coast-guard station at Atherfield Point runs along the southern flank of Shalcomb and Mottestone Downs. As we pass Brook Manor-house the ferruginous beds of greensand may be traced in the banks on the road-side; and Brook church is seen standing high up the hill on a terrace of those deposits. The relative positions of the strata in this district are displayed in the cuttings on the sides of the road from Shalcomb Down through the village of Brook to the sea-shore; as shown in

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LIGN. 18.-SECTION FROM BROOK-POINT TO SHALCOMB-DOWN; 1 MILE,

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lign. 18. If we proceed from the coast at Brook Chine through the village, and ascend the road by the church, and

ATHERFIELD POINT.

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over Shalcomb Down, we pass in succession, 1, the Wealden; 2, the Greensand; 3, the Galt; 4, the Firestone; and then cross the ridge formed by the highly-inclined strata of the White-chalk.

The turnpike-road leads through the villages of Mottestone* and Brixton to Shorwell, where it divides, and sends off a branch to Newport on the north-east, and another on the south-east, through Kingston and Chale to Blackgang Chine. About midway between Brixton and Shorwell a tenantry road turns off to the right, and admits a carriage to within a few hundred yards of the cliff, near the Atherfield coast-guard station. This is the most convenient place to alight, and reach the sea-shore near the junction of the greensand and Wealden formations. The path down the precipitous face of the cliff lies a little to the east of the station; it is a mere foot-track worn in the rock by the sailors and fishermen.† At a moderate distance westward of the spot where the path reaches the shore, is the headland called Atherfield Point, on which stands the station-house; and at its foot a ledge of rocks extends into the sea. Near this place, after recent slips of the cliff, and the removal of the fallen debris by the waves, the uppermost of the wealden deposits, and the lowermost of the greensand may be seen in juxta-position; in other words, the line of demarcation between the accumulated sediments of a mighty river-some primeval Nile or Ganges,

* On an eminence overlooking the village of Mottestone is a rude pillar of ferruginous sandstone called the "Long-stone," and which was probably erected as a landmark or boundary stone, at a very remote period. It is twelve feet high, and of an irregular quadrangular form.

This path is too precipitous and inconvenient to be attempted without risk by ladies or invalids. I have always visited the spot by this route, and am not aware of there being a more easy descent to the beach, except at a long distance from the most interesting part of the cliffs.

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