Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/747

1870.] (b) Mr. Prestwich has correlated the Brighton beach and the Sussex gravel-beds with the estuarine beds of Menchecourt, and has also remarked on the close resemblance which the Menchecourt beds bear, marine characters apart, to those at Fisherton, near Salisbury. The flint implements from the coast between Gosport and Southampton Water bear a corresponding resemblance to those from Fisherton and from Menchecourt. The ovoid type greatly predominates; and where, as at the Blackmore Museum, a large number of implements from the Hill Head gravels can be compared with a series from Fisherton, and from Milford Hill, near Salisbury, the general resemblance of the Hill Head and Fisherton specimens to each other and to the Menchecourt type, and the different character of the Milford Hill implements, and their resemblance to the spear-head form common at St. Acheul, are equally manifest. Adopting the supposition that the Avon flowed to the sea by Spithead, it is not difficult to trace a connexion between the Sussex and the Hill-Head gravels and the Fisherton beds. The gravel bordering on the north shore of the Solent carries on the Hill-Head gravel to Lymington, where an oval flint implement has been obtained from it, and on to Milford. Beyond this the coast is exposed to the open sea, and has been cut back, so that none of the lower level remains until the Avon valley is reached, six miles to the westward. There contorted gravel and brick-earth are seen in the cliff-section of the old river channel beyond Hengistbury Head, at from 20 to 40 feet above the sea-level, and thence the connexion of the valley-gravels up to Salisbury is plain. The plateau of Beaulieu Heath, which is about 70 feet above the lower gravel on the north of the Solent, and which corresponds in level and position to Titchfield common, stretches continuously to Poole, broken only by the river-valleys, as is shown in section No. 2. In the gravel covering of this tableland the flint implements of Bournemouth are imbedded, and it seems probable that the gravel of the plains at this level near the coast may correspond in age with the high-level valley-gravels, as it does in position with regard to the lower valley-gravels.

Having thus a sort of datum-line with which to compare the levels of the gravel covering the plains, it appears that while near the coast the tableland is but 50 or 60 feet above the lower valley-gravels of the Avon, at Fordingbridge it is 250 feet higher than beds with flint implements and Elephas primigenius, which lie about 40 feet above the river; and when the tableland attains its greatest elevation near Bramshaw Telegraph, it is 240 feet above the Fisherton beds in actual level, or if the plain were prolonged at the same inclination it would pass 400 feet above the Fisherton beds, and 320 feet above the top of Milford Hill at Salisbury.

It is remarkable that the inclination of this tableland, if prolonged still further, is found to touch the highest points of the country up to the source of the Avon; namely, Dean Hill, and Beacon Hill, Milk Hill, and Martinsell on the north of the vale of Pewsey.