94 



Burton: Lincolnshire Coast Boulders. 



decided on the evidence I have already adduced ; but a recent 

 visit to the Lincolnshire coast, combined with one to that of 

 Yorkshire, last September, has enabled me not only to verify 

 the evidence I have already given, but also to add to it. 



To begin with. It is a geological fact that the whole of the 

 Lincolnshire coast is composed of ' Newer Boulder Clay '— -the 

 ' Hessle and Purple clays ' above mentioned — and that over it 

 lies a covering of sand, thick enough to hide the clay beneath, 

 but thin enough, when swept by wind and waves, to reveal its- 

 presence ; so that patches of the clay can be seen, in various 

 places, all down the line. All these exposed clays are, more or 

 less, cut into long deep furrows with precipitous sides, by the 

 rise and fall of the sea ; some are furrowed right across, and 

 others on the margins only, like miniature fiords ; while the 

 surfaces are planed level, and are being gradually denuded by 

 the waves. On the surfaces the embedded stones can be seen 

 lying here and there, while small pits show where others have 

 recently been washed out ; and in the furrows, and on the sides 

 of the exposed clay beds, the stones are found lying in layers. 

 Wherever, in fact, these clay exposures occur, there you have 

 boulders, but on the loose sand there are practically none — only 

 one here and there at great distances apart. 



Beyond the outfall of the Bilsby Drain, about three miles 

 south of Sutton, where the land protrudes seawards, I found 

 a collection of stones, several hundred yards in length, near 

 the sand-bank ; and close to it were several exposures of clay 

 to account for its appearance. In all cases, indeed, where 

 stones occur, the clay is sure to be met with, though it may be 

 hidden from view temporarily by a gale. Amongst these stones 

 I found boulders similarly to those described in my first paper 

 on this subject— p. 133 of 'The Naturalist' for 189S — with true 

 rhomb-porphvry, gryphytes, ammonites, belemnites, and fossil 

 wood, etc. Several of the boulders were beautifully marked 

 with ice-scratches, as fresh as any newly taken out of their 

 beds can be, making it impossible for them to have travelled 

 far ; and all the boulders, with but few exceptions, were angular 

 or nearly so ; those approaching at all to smoothness, such as 

 sandstones and hardened clays, having, no doubt, been rolled by 

 the waves when lying together in the furrows referred to, or 

 such like places. There was an exposure of clay in one place 

 some acres in extent, larger than any I have before seen, where 

 the action of the sea in denuding the surface and cutting the 

 mass into long, narrow furrows was beautifully shown ; and, 



Naturalist,. 



