102 Professor Edward Hull — Gravel Beds, Isle of Wujht, etc. 



stratified. The section of the gravel cliff is fully described in the 

 Survey Memoir.' 



The gravel-bed on the summit of the cliff above Alum Bay is 

 distinctly visible from the deck of the ship anchored in the bay below ; 

 and its horizontal sti'atification, resting on the nearl}^ vertical strata of 

 the Tertiary Series, forms one of the most interesting geological 

 features of the country. Its presence there is easily explained. It 

 once extended westwards to an undefined distance, but with the 

 underlying Tertiaries it has been worn back along the side of the 

 ridge of the Chalk, which now stretches to the Needles, but once 

 extended to a greater distance towards the Isle of Purbeck. The 

 Chalk ridge at the Tennyson Monument rises to a level of 483 feet, or 

 somewhat under 100 feet above the level of the gravel beach from 

 which the flint pebbles were derived by ordinary wave action. It is 

 impossible to conceive of a more excellent example of the production 

 of shingle at the base of its cliff at a former epoch, such as we 

 are able to observe along our coasts at the present time. 



Part III. 



Dorset and the South of England. — It is unnecessary for me to 

 describe at any length the plateau gravels, as they have been so fully 

 described by Codrington and the officers of the Survey, while they are 

 represented on the 1 inch Survey Map. That there are numerous 

 deposits of sand and gravel at low levels along the coast of 

 Southampton Water and the Solent is well known, and they are 

 of peculiar interest as containing evidence of man's presence and of 

 extinct animal remains. But what concerns us most in regard to the 

 present inquiry is the upper limit of the plateau gravel beds to 

 be found in the New Porest at levels corresponding very closely 

 to those in the Isle of Wight. By way of illustration I shall refer to 

 one or two examples visited by myself on the occasion of a recent visit 

 witli members of the British Association. Lyndhurst Church stands 

 on Tertiary beds, at a height of 139 feet, but to the north and west 

 the ground rises gradually, and on i-eaching Stony Cross Plain at 

 a height of 373 feet we find ourselves on the margin of an extensive 

 terrace, rising at Long Cross Plain to a height of 414 feet, but sloping 

 gradually, in the direction of the River Avon, to the west ; the average 

 level is about 350 feet. The plain is formed of beds of gravel 

 composed chiefly of rounded flint-pebbles and occasional bands of sand, 

 and numerous shallow sections are supplied by the pits which are 

 worked for road-stone to a few feet from the surface, which extends 

 unbroken to the edge of the valley of the Avon and its tributaries. 

 It is impossible not to recognize the similarity of the conditions on 

 both sides of the Solent, though separated by an interval of about 

 25 miles. In each case we have beds of rolled flints, spread out 

 in sheets with flat, or slightly inclined, surfaces, and reaching levels 

 of nearly 400 feet above the sea, from which they descend by gentle 

 slopes to the sea-margin. The origin of the flint-pebbles is beyond 



' Geol. Isle of Wight, 2nd ed. The correct level of the upper surface of 

 St. George's Down, as given in the Ordnance Map, is 365 feet. Probably that 

 of the cliff at Alum Bay is somewhat lower. 



