Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/734

532 while formerly, it was much more. In 1757 and 1789–1794 the gravel in Hordwell Cliff is described as being from 18 to 20 yards thick; and later, in 1821, Mr. Webster gives the thickness in Barton and Hordwell cliffs as at least 50 feet. As the coast is wasting at the rate of a yard a year, the cliffs which exhibited this thickness of gravel were from 60 to 80 yards in advance of the present coast, and inland the thickness diminishes still more, being only 9 feet in pits about half a mile from the cliffs.

Chuton and Becton Bunnies are cut out in the bottom of higher and broader valleys, on the flanks of which the gravel thins out. The chines in the sandy cliffs to the westward of Bournemouth furnish many sections in which the relations of the older valley and the chine with the gravel covering the plain can be observed. In Allum Chine a bed of gravel and the overlying brick-earth have been cut away by the older valley, on the side of which lies a bed of white gravel, overlapping the edges of the brick-earth and the lower gravel. The chine itself has cut through the white gravel.

Towards the entrance of the Solent the coast-line trends seaward,and the tableland is prolonged to a lower level. Inside Hurst Castle, where the coast is sheltered from the open sea, the gravel plain falls with a gradual slope almost to high-water level (Section No. 5). This is the case all along the shore of the Solent to Eaglehurst, at which point the coast is exposed to the open sea from the direction of Spithead, and has been cut back, and the cliff is consequently higher. At the lower level the country here does not present the same tabular character; from the 100-feet level downwards, the fall appears to be more by steps, and the surface has, moreover, been a good deal modified by the streams.

The plains of Boldre and Beaulieu Heath present the tabular character before described, and rise gradually to an escarpment, which is 140 feet above the sea towards Brockenhurst, and 120 feet near Southampton Water. Northward of the escarpment the general surface of the country is 80 or 100 feet lower, much intersected by the tributary streams of the Beaulieu river, and generally covered by a wash of gravelly loam; but detached gravel-topped hills rise in the lower ground to levels corresponding to the plains, and are evidences of the former extension of the tableland beyond its present northern edge.

The Boldre river, and the Exe or Beaulieu river, flow in well-defined valleys through the tableland, as is shown in section No. 2, which crosses the river-valleys at right angles. In section No. 5, which is nearly parallel to the Boldre river, the bottom of the valley is shown by a dotted line. The fall of the valley is only 4 feet per mile, while that of the tableland adjoining is about 20 feet per mile.

(b.) The tableland of Beaulieu Heath abuts boldly upon the western shore of Southampton Water, as section No. 2 shows; but