The gravels found lower down the course of the river, at Hill Head, Brown Down, and Lee on the Solent, appear to belong to a somewhat later period; and to bear much the same relation to those of Southampton Common, as do the beds at Shrub Hill to those of Brandon Down. As I pointed out long ago, "There can be but little doubt that these gravel beds are merely an extension of the valley-gravels of the rivers Test, Itchen, Hamble, and other streams, which at the time they were deposited, flowed at this spot in one united broad stream, at an elevation of some forty feet above the existing level of their outfall, over a country which has since, by erosive action, been in part converted into the Southampton Water."[1] We shall shortly have to revert to this circumstance; but before returning to the coast, we must take a short glance at the features of the discoveries near Salisbury.
In the neighbourhood of this city there can be no doubt of the deposits being thoroughly in accordance with the river theory. The Fisherton and Milford Hill beds occupy points or spurs of land, in the forks above the junction of streams, or precisely those spots in which their presence was to be expected. There are the usual beds of gravel, sand, and clay, the usual bones of the Quaternary fauna, some representing what are now Arctic species, and therefore presumably indicative of a severer climate than at present; and the usual land and freshwater shells. Though the valleys, being confluent, are excavated to the same depth, yet, on examination, their sectional areas will be found to be approximately proportional to the extent of country drained by the rivers still flowing through them. At Milford Hill, the deposit is cut off from the main spur of land by a kind of transverse valley, about thirty feet in depth, besides having on either side a valley some 100 feet deep. On any hypothesis of the beds having been deposited by aqueous action—and no other can for a moment be entertained—these valleys must have been mainly excavated since the deposition of the gravels. For had the valleys at that time existed, we can conceive of no conditions under which a body of water sufficient to fill the valleys to their summit, and able to carry along detrital matter with it, would leave its heavy contents at the top of the hills instead of at the bottom. The old fluviatile beds occur also at various levels on the slopes, in complete accordance with the theory of gradual excavation; and farther down the valley, at
- ↑ Q. J. Geol. Soc., vol. xx. p. 189.
