116 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 13, 



noticed, as in every other, there was a total absence of any detritus 

 below this old terrestrial surface. 



I am well aware that, in the majority of cases where drift-gravel 

 beds are seen in superposition on inferior strata, there are no indica- 

 tions of terrestrial conditions ; but it must be borne in mind that at 

 every time, as now, the accumulation of peaty matter is a local and 

 exceptional case ; and all that can be expected is, that it should 

 occur when the old configuration of the surface rendered its formation 

 possible. This old land-surface supplies us with a definite and 

 valuable, though isolated, date in the geological history of a large 

 area north of the Wealden denudation. 



I would here refer to one or two instances, in order to show that 

 old terrestrial surfaces of like age with those in the north of the 

 Wealden area exist elsewhere. 



Isle of Wight. — I had previously visited the locality indicated by 

 Sir H. Englefield, whose description* will still be found most accu- 

 rate, that " near the top of the cliff lie numerous trunks of trees, not 

 lodged in the undisturbed strata, but buried 8 or 10 feet under sand 

 and gravel. Many are 1 foot or 2 feet in diameter, and 10 to 12 

 feet in length ; their substance is soft, but their forms are distinct ; 

 and with them occur considerable quantities of small nuts, like those 

 of the hazel." He adds that no hazel now grows upon the island ; 

 nor has the subversion of the trees been an event of recent occur- 

 rence. I had further an opportunity of seeing, in company with the 

 late Prof. E. Forbes, his own discovery of an instance of terrestrial 

 surface infraposed to the Drift-gravels, at the east end of the Isle of 

 Wight, near St. Helens ; which he noticed in a communication on 

 the newer Eocenes of that locality, but which has been omitted in the 

 published abstract. The beds themselves present the usual characters 

 of all accumulations of vegetable matter in low damp situations, in- 

 cluding the remains of trees of large size. The beds contained the 

 remains of Insects. 



The overlying gravel-beds are developed on a grand scale, forming 

 part of a band in the noi'th of the central chalk-ridge of Brading and 

 Bembridge Downs ; and corresponding with that which occupies the 

 central valley, along the line of the anticlinal of the island, — or to the 

 south of the same ridge. The Brading gravels, where thickest, as 

 near Foreland, have a marked bedded arrangement, which is not quite 

 horizontal, but inclines towards the chalk-range. The materials have 

 been derived from the chalk, but, though from Foreland the gravel 

 extends southward over the edges of the upturned Eocene beds, they 

 stop short, and do not reach the chalk-strata. The like happens with 

 respect to the gravel-masses of the south side of the central range, 

 along the Yar. They will be seen to be separated from, and to range 

 below the level of the chalk, — in other words, they have not been 

 produced by the abrasion of the chalk-strata now nearest to them ; 

 thus showing, in conformity with what has been noticed respecting 

 the longitudinal valleys of the Wealden, that they were destitute of 

 detritus before the Drift-gravel Period. The superposition of the 



* Englefield's Isle of Wight, p. 132. pi. 22. 



