Page:Quarterly Journal of the Geological Society of London, vol. 28.djvu/64

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38
PROCEEDINGS OF THE GEOLOGICAL SOCIETY.
[Dec. 6,

advancement of geological knowledge placed at their disposal by their late distinguished Fellow.

Mr. J. Gwyn Jeffreys seconded this proposition, which was carried unanimously.

The following communications were read:—

1. On the presence of a Raised Beach on Portsdown Hill, near Portsmouth, and on the occurrence of a Flint Implement on a high level at Downton. By Joseph Prestwich, Esq., F.R.S. &c.. President.

A few years ago[1] I traced the well-known old beach of Brighton past Arundel to Chichester and Bourne Common—a distance of 42 miles. At Brighton it is only from 8 to 12 feet above the level of the present beach; near Arundel it attains a height of 100 feet, near Chichester possibly of 130 feet, and at Bourne Common of 140 feet. Westward of this point it had been found on the east coast of the Isle of Wight; but I failed to detect it at any point inland, or at any considerable elevation.

I now beg to call attention to an interesting section which I have more recently observed at a spot 10 miles westward of Bourne Common, and 5 miles inland. It is a mile and a half E.N.E. from Fareham, on the right-hand side of the lane leading from East Cams to Nelson's Monument, which stands on the western extremity of Portsdown Hill. This hill, as is well known, is a bare narrow chalk ridge, running 6 miles from east to west, and rising in the midst of a lower surrounding Tertiary area to a height of from 300 to 400 feet. The subangular flint-gravel of Chichester, Havant, and Portmouth ranges up to the southern foot of the hill, to a height of about 40 feet above the sea-level. It may be seen in a pit by the side of the railway half a mile west of Porchester station.

Above this lower level the slope of the hill here consists of bare chalk, with the exception of this one spot, on the north side of East Cams Wood. Although the pit is close by the road, it is not readily seen. It is situated at a height of 125 feet above the sea, or of 85 feet above the ochreous flint-gravel at its base—whence the latter stretches westward, forming the great plains of gravel extending past Havant and Southampton to Poole, which have been so well described by Mr. Codrington[2].

The pit is a shallow arc, and presents the following section:—

a. Grey earth and sand, with angular and rolled flints, 0 to 2 feet.
b. Light-coloured laminated sands, with seams of shingle,
c. Light-coloured coarse flint-shingle, with a few whole flints,
4 to 6 feet.
d. Chalk rubble, patches of.

The beds b and c constitute a true shore-shingle, composed of rolled and imperfectly rounded flints, imbedded in a matrix of light-coloured sand and loam, very different from the ochreous subangular

  1. Quart. Journ. Geol. Soc. 1859, vol. xv. p. 215.
  2. Ibid. 1870, vol. xxvi. p. 528.