Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/172

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134
F. W. HARMER ON THE KESSINGLAND CLIFF-SECTION.
8. On the Kessingland Cliff-section, and on the Relation of the Forest-bed to the Chillesford Clay, with some Remarks on the so-called Terrestrial Surface at the base of the Norwich Crag. By F. W. Harmer, Esq., F.G.S. (Read November 8, 1876.)

In the "Outline of the Geology of the Upper Tertiaries of East Anglia," given by Mr. S. V. Wood, jun., and myself in the volume of the Palæontographical Society for the year 1871, we called attention to the beds at the base of the Kessingland cliff and their relation to the Crag and Chillesford clay, and gave a section of them. Up to that time the cliff had been, at the time of our visit, more or less obscured by talus, so that some uncertainty existed as to the superposition of the different beds. After a storm in the month of November 1874, however, I was fortunate enough to find the section perfectly clear; and the result of my examination of the cliff was laid in the same month before the Geological Society of Norwich; but that body does not publish any record of its proceedings.

In all respects, so far as the sequence of the beds is concerned, this recent exposure confirmed the representation given by Mr. Wood and myself in 1871; but in one matter of detail, then left doubtful, some correction is necessary.

As Mr. Gunn has recently submitted to this Society a paper describing his view of the section[1], which, in my opinion, differs entirely from what was then so clearly revealed, I think it desirable to give a short account of the facts as they then appeared to me.

The beds present in the cliff-section I take to be, in ascending order, as follows:—

1. A stratified deposit of clay and sand, which appears to be the Chillesford Clay.

2. A tough unstratified clay of a mottled slate-blue colour, shown in places to be underlain by sand and gravel, which is penetrated by rootlets, and which, with the gravel, yields mammalian remains.

3. A lenticular bed of laminated sand and clay.

4. The Middle Glacial sand and gravel.

5. The Upper Glacial, or Chalky Boulder-clay.

No. 1 occurs for the space of 400 yards to the north of the Pakefield-Lighthouse gorge, and for a short distance to the south of it. It is occasionally exposed on the beach, but is generally to be seen in section at the base of the cliff. It is horizontally stratified up to its junction with bed No. 3, and is evidently the denuded remnant of some formerly much more wide-spread deposit. It resembles the Chillesford Clay in appearance, being composed of alternating layers of fine sand and clay; and although it cannot be positively identified with that formation, owing to the absence of shells, there seems to be little question about it.

No. 2 extends from nearly the southern termination of the cliff

  1. Quart. Journ. Geol. Soc. vol. xxxii. p.123.