DRIFTS OF FLAMBOROUGH HEAD. 389 



marked both by gravels and by the empty channel *, and with very 

 little artificial aid the Gypsey llace might be sent once more to the 

 Humber. 



III. General Distribution of the Drift. 



Attention has frequently been directed to the fact that in East 

 Yorkshire the Glacial deposits attain their greatest development at 

 or near the coast-line. 



This structure is strikingly exemplified on Flamborough Head, 

 for, as alread}" mentioned, on the south side the drifts are banked 

 deeply against the inner slope of the Wolds, and on the north they 

 are heaped up in thick mounds and ridges on the very summit of 

 the escarpment, while inland they thin away so rapidly that the 

 Chalk often carries nothing more than a scanty covering of clay 

 within a few hundred yards of the edge of the cliff. 



The kame-like mounds and ridges on the north side form a dis- 

 tinct chain (see fig. 1) which follows the highest part of the Chalk 

 ridge south-eastward from Speeton to San wick, and there, where 

 the cliff falls suddenly to 150 feet, leaves the coast and crosses 

 direct to the opposite side of the headland, passing close by the 

 village of Flamborough (as indicated on the map). Westward from 

 Speeton also, this chain is extremel^T- well-marked on the crest of 

 the escarpment as far as the village of lieighton, a distance of about 

 two miles ; and it attains in this, the highest portion of its course, 

 its maximum development, both in thickness and in sharpness of 

 feature. jS^ear Reighton it descends the escarpment and enters 

 the Vale of Pickering, where, though its western edge is still well 

 defined in the neighbourhood of Muston and Gristhorpe, its eastern 

 boundary is less easy to trace, and merges into the general mass of 

 the Glacial beds which block the mouth of the valle3\ Where this 

 chain rests on the edge of the cliff, as at Speeton, Buckton, and 

 Sanwick on the north side of the headland, and at Beacon Hill on 

 the south, the structure of the mounds is frequently clearly revealed 

 in the sections (see PI, XTII. figs. 6, 10, and 12). In such cases 

 the mounds are found to be largely composed of stratified material, 

 often showing arched bedding. To the seaward of this chain, 

 where it leaves the cliff, as at Flamborough and Speeton, a thick 

 and complex mass of drift-gravels and Boulder-clays chokes the old 

 valleys, while, on the opposite side, as a rule, only one thin Boulder- 

 clay is present, and the valleys are open, or are filled with local 

 gravels only. 



The late Prof. H. Carvill Lewis, by whose untiniely death in the 

 midst of his labours so much was lost to glacial geology, examined 

 these ridges with me early in 1887, and declared that they had 

 marked the terminal limit of the great ice-sheet, and were the finest 

 example of a true terminal moraine that he had yet seen in 



* For a fuller discussion of this part of the subject, see my paper on ' Glacial 

 Sections nt-ar Bridlington.' Part iii., in Proc. Yorks. Geol. & Polyteclin. Soc. 

 vol. viii. (1883) pp. 251 & 252. 



