distance of the coast, when they begin to fall more and more rapidly through a ravine, which has been cut out in the bottom of a valley corresponding in level and cross section, and continuous with that in which the stream flows before it enters the ravine. The increased rate of fall towards the sea is opposed to the general tendency of streams to fall less as they near their outfall, and it seems to point to a somewhat sudden change in the conditions under which the streams flowed. Such a change would result if the streams which were tributaries of a river flowing to the Solent by Freshwater had been provided with new outfalls by the cutting back of the coastline, until the river and its branches were intersected while still flowing at a considerable height above the sea. If this be the true explanation of the occurrence of the chines at the back of the Isle of Wight, it would seem to be a fair inference that where chines, or bunnies, are found, a similar change in the outfall of the streams has taken place.
(e) The section of gravel exhibited in the cliff round Foreland Point, at the eastern extremity of the Isle of Wight, seems to deserve a more detailed description than it has hitherto received, although it has been often mentioned[1] in notices of the superficial deposits of the neighbouring country.
Fig. 12 (Pl. XXXVII.) represents the section exposed in the coastline from Whitecliff Bay, round the headland. The main mass of gravel consists of rounded chalk-flints, imbedded in sand and distinctly stratified in layers of pebbles of assorted sizes, dipping slightly northward. The flints, though well rounded, have not the finish of the pebbles in tertiary pebble-beds, and the structure shows it to be a beach-deposit. Seams of pure sand overlie bands of pebbles as large as oranges, and layers of pebbles stained a dark red are succeeded sharply by bands of white pebbles. Pieces of sandstone, and fragments of chert and sandstone from beds below the chalk, are occasionally met with. The thickness is between 30 and 40 feet, extending from a few feet above high-water mark to 60 feet above the mean sea-level. The general colour is a red-brown, and it is only near the overlying brick-earth that there is any admixture of clay or loam.
No organic remains of any sort have been found in this gravel. In structure it is exactly like a beach-deposit, and in many respects unlike the gravel covering the high ground of the north of the island and the mainland.
Gravel of a similar character is said, by Mr. Godwin-Austen[2], to occur at St. Helens, and is supposed by that gentleman to be a continuation of the Foreland bed. A deposit of gravel on the shore to the east of Ryde is described by Mr. Bristow[3] as consisting of "white rounded flint-pebbles in brown clay, precisely similar to
- ↑ Forbes's Memoir, p. 6; Memoir of the Geological Survey of the Isle of Wight, p. 103; Godwin-Austen, Quart. Journ. Geol. Soc. vol. xi. p. 116; Prestwich, Quart. Journ. Geol. Soc. vol. xv. p. 215.
- ↑ Forbes's Memoir on the Fluviomarine Tertiaries of the Isle of Wight, p. 7.
- ↑ Memoirs of the Geological Survey of the Isle of Wight, p. 102.
