Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/736

534 No. 8 from Stubbington, northwards. Titchfield common and the tableland about it is gravel-covered; but this appears not to be the case with the corresponding level between Titchfield and Fareham. The lower level of Brunage, Hill Head, Stubbington, and Alverstoke is almost uniformly covered with gravel or brick-earth. The section which is seen in the cliff between Hook and Browndown has been well described by Mr. Evans ; the cliff is everywhere less than 40 feet above the mean sea-level, and the gravel in several places reaches as low as high-water mark.

From Browndown a low inland cliff, which rises above the shingle of the rifle-ranges, runs inside the fortification-ditch as far as the railway at Anglesea, and marks the boundary of the gravel which covers the level of Lee, Grange, and Alverstoke. Between this cliff and the shore lies a level tract more than three miles long and a quarter of a mile wide, and but little above high water. The structure of the shingle composing it was exposed in extensive excavations made to obtain materials for the concrete blocks for the Spithead forts. It is evidently a recent beach-deposit due to existing conditions. It has not the coherence or the ferruginous colour of the gravel in the cliffs of Brunage and Lee, from which it also differs in containing numerous oyster and other shells; but the materials are the same, flints but little rolled, with frequent seams of sand, and in general structure there is a good deal of similarity.

About Portsmouth a low gravel-covered flat, which is apparently a continuation of that on the Gosport side of the harbour, extends to the base of the chalk range of Portsdown Hill, to the east of which the lower level is again divided from a higher gravel-covered surface 140 feet above the sea by a slope. Section No. 9 through Hayling Island, and passing half a mile to the west of Bourne Common, to which point the westward extension of the Brighton beach has been traced by Mr. Prestwich, shows a very similar outline to the sections near Titchfield (Nos. 7 & 8). Still further eastward are the remains of the old sea-bed at Avisford and Waterbeach with marine shells at from 80 to 100 feet above the sea-level, to the south of which lies the low ground of Selsea, covered with marine gravel containing large blocks of syenite, porphyry, granite, &c. and overlying the mud-deposit of Pagham, which contains littoral shells of southern species, with remains of Elephas antiquus.

(c) The gravel varies but little in character or composition over the area which has now been described; it consists almost exclusively of chalk flints, little rolled and often perfectly fresh. There is always, however, a proportion of tertiary pebbles; and where, as between Bournemouth and Christchurch, extensive pebble-beds occur in the underlying tertiary strata, the proportion of pebbles in the