546 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 8, 
An argument for the great antiquity of the gravel of Milford 
Hill, at Salisbury, with its imbedded implements, has been justly 
based on the circumstance that since it was deposited the valley of 
the Avon has been deepened some 80 feet, and that after by far the 
greater part of this deepening had been accomplished, the Mammoth, 
Rhinoceros, Lion, Hyena, Marmot, Lemming, We. left their remains 
in the Fisherton beds. The same line of reasoning shows the far 
greater antiquity of the gravel on the higher plains of the New 
Forest, of that on both sides of the Itchen, near Southampton, and 
near Newport, in the Isle of Wight, more than 250 feet above neigh- 
bouring valley-gravels containing Elephas primigenius, &e. 
(c) But if the great height attained by the gravel-covered plains 
is evidence of an antiquity far greater than that of the Milford Hill, 
and other high-level valley-gravels, the uniform surface of the 
tableland points to a continuance of similar conditions from the 
time of deposit of the highest gravels down to that of the gravel 
containing flint implements at Bournemouth, Lymington, Hill Head, 
&c. What these conditions were is open to question; there are no 
organic remains by which to decide whether the gravel covering 
these wide plains is an extension of the gravels of the neighbouring 
rivers, or a marine deposit, like that covering the southern part of 
Sussex. 
It has already been pointed out that, probably down to the time of 
the low-level valley-gravels, the Isle of Wight was connected with 
the mainland, and a river, comprising in its drainage-area the basins 
of the rivers now reaching the sea at Poole, at Christchurch, and by 
Southampton Water, flowed by Spithead to the sea. Fig. il is a 
map of the catchment basins of the rivers in question*. The area 
drained by all the rivers entering the sea from Poole to Portsmouth, 
together with the Isle of Wight, and Christchurch and Poole Bays, 
out to the 10-fathom line, is 2750 square miles, equal to ? the area of 
the basin of the Thames above Hampton. Of this area, 666 square 
miles, or nearly 3, is comprised in the basin of the Avon, 544 square 
miles in that of the Test, and 479 in that of the Stour; while only 331 
square miles, or less than 1, is drained by the rivers entering Poole 
Harbour. The hydrographical area of the old river appears there- 
fore to have been comparatively small, and but little augmented by 
the western river-basins. Within it, however, lie the large grayel- 
covered surfaces which have been described. Of these the New- 
Forest tableland alone slopes in the direction of the principal lines of 
drainage ; it occupies the watershed between the Avon and the Test, 
and falls in the direction of their flow at the rate of from 18 to 34 feet 
permile. The tableland on the east of Southampton Water slopes at 
the rate of from 30 to 120 feet per mile towards the water, and the 
Isle of Wight tableland at from 30 to 40 feet per mile northward. 
The flattest of these inclinations, that of the New-Forest tableland, 
is, for the course of a river, very great, and such as only mountain- 
eee from the Map to accompany the Report on Salmon-Fisheries, 
