Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/62

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36
G. H. KINAHAN ON THE CHESIL BEACH, DORSETSHIRE,

2. It lies on the N.E. shore of Lyme Bay (the large bay between Start Point and Portland Bill).

2. It lies on the N.W. shore of Wexford Bay (the shallow bay between Greenore and Cahore Points).

3. This beach is a barrier dividing the lagoon called The Fleet from the open sea (Lyme Bay). The Fleet has its embouchure into the sea on the east of Portland Island. This high tract must have been an island when the sea was a little higher than at present.

3. This beach fringes a long irregular accumulation of Æolian drift (blown sand), this latter dividing a reclamation, or intake, formerly a lagoon, from the sea in Wexford Bay. The ancient lagoon had its embouchure into the sea on the south of Cahore highland, which hill was an island when the sea was a little higher than at present.

4. The pebbles in the beach graduate regularly from sand at the western end to shingle at the eastern end.

4. The beach in its southern part is a mixture of sand, gravel, and shingle; while near its north end it is a clear shingle.

5. Towards the eastern termination the beach increases considerably both in bulk and height.

5. Towards the north the beach slightly increases in bulk, also nearly due west of the north end of Rusk Bank.

6. The beach ends at Chesilton, some distance north of Portland Bill.

6. The beach terminates 400 yards S.S.E. of Cahore Point.

7. Many of the pebbles in the beach are similar to those found on the west shore and in the country west of Lyme Bay, but especially in the "raised beach" that occurs in places at Start Bay and elsewhere.

7. Many of the pebbles in the beach are fragments of the rocks only found in the country south of Wexford Bay, but especially between Greenore and Carnsore Points.

8. Possibly most of the pebbles found in Chesil beach have travelled from the westward across the deep water in Lyme Bay. According to the records of different observers some pebbles travel eastward, along the north shore to Pinney Bay, immediately west of Lyme Regis; but, according to the Admiralty Chart, there could not be a continual tidal driftage round the shore of Lyme Bay from the Start to Chesilton, as

8. Many of the pebbles found in the Cahore shingle beach must have travelled across the bay from Greenore[1], as there is not a continuous travelling of the beach round the shore of the bay. From Greenore some fragments of the Greenore rocks travel, first westward and then northward, round the shore of the south or Ballygeary Bay; these, however, with others that have come across the deep water, collect as shingle on

  1. I am informed by T. Winder, Esq., M. Inst. C.E., that during last summer, while making a submarine survey for the extension of Ballygeary Pier, he ftnind a stream of pebbles travelling northward across the bay from Greenore.