NOTES ON THE COAST BETWEEN BRIDLINGTON AND FILEY.

BY G. W. LAMPLUGH, F.G.S., OF H.M. GEOLOGICAL SURVEY.

I will presume that the party on reaching Bridlington make their way to the North Cliff, and walk thence along the shore to the beginning of the Chalk-cliffs at Sewerby. They will notice that the sections under the town are now wholly hidden by sea-defences, the need for which is well brought out by the present contour of the coast-line, a definite projection now marking the protected portion, especially on the south side of the town. This projection will doubtless become in time more marked, as the sea gradually develops its flank attack.

The details of most of the sections now concealed have been recorded, with illustrations, in the past volumes of the Society, and may be consulted by any member requiring information regarding them. (See Vol. VII. (1881), p. 383; Vol. VIII. (1882), p. 27, and (1883), p. 240 (with map of neighbourhood); and Vol. XI. (1889), p. 275).

One of the most interesting points thus hidden is the existence in the lowest (Basement) Boulder Clay of transported masses of shelly sand and clay, containing a rich molluscan fauna with wellmarked Arctic characteristics. These masses constitute the deposit formerly known as the "Bridlington Crag." A fine collection of their contents has been made during favourable opportunities by Mr. W. B. Headley, of Bridlington Quay. A shred of similar composition, containing a few shells, may be seen in the drifts above the chalk-cliff at Flambro' South Landing, three miles distant, in a rather inaccessible position. My view of these shelly patches is that they were torn from the sea bottom, and carried forward into their present position by the great ice-sheet in its advance upon our coast.

As the members walk along the cliffs towards Sewerby they will notice that the sections, though much obscured by slipping, show two and sometimes three distinct bands of boulder clay, separated by irregular deposits of stratified material, and that the cliff top is held

by a considerable thickness of chalky gravel (The Sewerby Gravels). The different bands of boulder clays probably mark oscillations of the margin of the ice-sheet, and the overlying gravels seem to have been spread out by a body of fresh water, draining from the Wolds, and arrested here either by higher land now swept away by the sea, or by the edge of the decaying ice-sheet. The stratified sands and warps (Hilderthorpe Series), so well exposed in the cliffs south of Bridlington Quay, can be well explained as the sediment of the same flood in its quieter, deeper waters.

One of the most interesting sections of the whole coast-line is that which will confront the members at the commencement of the Chalk, though probably they will find its most important elements somewhat obscured by slipped material. An ancient sea-cliff of Chalk, buried and obliterated under glacial deposits, is here revealed. In 1887 and 1888, by means of a grant from this Society and from the British Association, we excavated the material banked against this buried cliff, and in doing so obtained a large collection of fragmentary remains of mammals, fish, and birds, which are now preserved in the Museums of York and Jermyn Street. Elephas antiquus, Rhinoceros leptorhinus, Hippopotamus amphibius, Bison sp., Ilyana, Arvicola amphibius, Gadus morrhua, were among the species identified. At the base of the cliff we found a sea-beach of rolled chalk pebbles, and overlying this a clayey land-wash with some small landshells, passing up into an ancient blown sand which was piled quite to the top of the old cliff, and had helped to preserve it during the rigours of the subsequent glaciation. (Further account of this interesting section will be found in Proc. Y. G. & P. Soc., Vol. IX., pp. 381-92). I regard these "Buried-Cliff-Beds" as older than of the glacial deposits of East Yorkshire, and they are very valuable to us as an indication of the physical conditions of the area before the great glaciation. We can be sure that at that time Holderness formed a wide bay, with the sea running quite up to the foot of the Wolds, its shore-line approximating to the present course of the railway from Hull to Bridlington.

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The locality deserves further investigation, and I hope the Society will again undertake it when the sea by removing the overhanging material which stopped our work enables this to be done in safety.

I shall presume that the chief attention of the members in their further progress north-eastward will now be directed to the Chalk. They might however still profitably give an eye now and again to the capping of drifts, of which a detailed description, with figures, will be found in Q. J. G. S., Vol. XLVII., pl. xiii., p. 384.

With regard to the Chalk, there is still much work to be done in working out its subdivisions and thickness. I had made some progress in this direction before leaving the neighbourhood, and had intended to do more. Possibly I may find it practicable before long to sum up for this Society the information already obtained, in the hope that it may be of use to future workers.

The fossil Sponges, for which the Chalk of Flambro' Head is celebrated, will be found most plentifully between Sewerby and Danes Dyke, being quite rare to the eastward of the latter place. Marsupites ornatus, another interesting fossil, is abundant, though usually in an imperfect condition, in a band which rises into the cliff two or three hundred yards west of Danes Dyke. Up to the South Sea Landing there is a steady rise of the Chalk northward, but beyond it the strata lie more nearly horizontally, partly owing to the cliffs here being nearly along the strike of the beds; and in going thence to the extreme point of the headland we pass very little lower in the series.

The numerous small faults which break the Chalk may be noted in passing. I measured a large sequence of them, under the impression that they might prove in the aggregate to represent a considerable throw in one direction; but the investigation showed that they frequently nullify each other, and that they probably mask what in less jointed beds would take the form of low undulations of the strata,

No flint occurs in the Upper Chalk, but nodules of this substance make their appearance on the shore at High Stacks, a little south of the Lighthouse, and thence are brought rather rapidly to the cliff top at the Fog-gun House by the renewed rise of the Chalk consequent upon the alteration in the trend of the cliff-line.

If the members have time to visit this locality they will find many points of interest. An ancient ravine in the Chalk has been buried under the drifts here (such as may be noticed also at South Sea Landing and at Danes Dyke), and has given rise to a curious

conformation, the sea having penetrated into it by two caves, through which the loose material has been withdrawn, so that two large pitlike "blow-holes" have opened up near the edge of the cliff. There is a fault in the Chalk, accompanied by much contortion and the formation of veins of calcite in the shattered rock, in the centre of Selwicks, a northerly downthrow bringing, for a short distance, the flintless Chalk once more into the cliffs. (See Y. Geol. and Pol. Soc., Vol. VII. (1880), p. 242, for further description). The lower part of the drifts around Selwicks is largely composed of re-arranged Speeton Clay; and fragments of the characteristic fossils of that formation are quite plentiful here, as are also transported fragments of marine arctic shells.

FIG. 2.-SECTION AT THE TOP OF THE CLIFF AT COMMON HOLE, SELWICKS, SHOWING SURFACE-CONTORTIONS IN THE CHALK. (G. W. LAMPLUgh).

The wavy lines represent the bedding-planes of the Chalk-with-flints: top layers broken into rubble. Above is seen the dark Basement' Boulderclay.

From Selwicks to the high cliffs of Buckton, the sections are made up entirely of flinty Chalk, with a variable capping of drifts. To the hardness of the rock, as much as to the tumultuousness of the sea, is due the fantastic and picturesque outlines into which this part of the coast is broken.

At Old Dor, opposite to Bempton, the beds are magnificently contorted, being thrown into sharp folds from the top to the bottom of a cliff 275 feet high. Photographs of this fine section were issued to the members in 1882, and a photograph of Little Thornwick Bay, two miles to the south-eastward, in 1885; and in each case a brief description of the locality will be found in the annual volume.

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