Rev. T. G. Bonney — On the Roslyn Hill Clay Pit. 403 



tions on liill-slopes, I could not give up the belief that the loam (espe- 

 cially where the imbedded stones are angular, and still more especially 

 where the loam is associated with large angular blocks) is what Victor 

 Hugo would call a "veritable construction." I now however believe 

 that this stony loam is not the equivalent of the brick-clay of the plains 

 of the N.W. of England, but that it is on the horizon of the part of 

 the middle sand and gravel which is found on the hill-sides, or on 

 the borders of the hills. That the eskers of Ireland and kames 

 of Scotland were piled up during some part of the Middle Sand 

 and Gravel Period can, I think, scarcely be doubted ; and I now 

 see reason for believing that the second submergence which I have 

 supposed necessary for the accumulation of the upper or brick clay 

 of the plains was of very limited extent, and that this clay seldom 

 rises higher than 400 or 500 feet above the present sea-level — the 

 boulder-clay at higher levels in Lancashire, Yorkshire, Cheshire, and 

 the Welsh borders, being the equivalent of the pinnel of the Lake 

 District. 



The drifts of Scotland and the N.W. of England cannot, I believe, 

 be correlated without regarding the English upper or brick clay 

 (above which there are no eskers or kames) as the representative of 

 the Scotch shelly clay. My pinnel may possibly represent both 

 the till and boulder-clay of Mr. James Geikie ; and the more 

 ancient blue clay of the N.W. of England and Wales may be on 

 the horizon of the lower or dark till of Swedish geologists. 



VI. — Notes on the Eosltjn Hill Clay Pit. 



By the Eev. T. G. Bonney, M.A., F.G.S. 



(Read before the Cambridge Philosophical Society, May 13, 1872.) 



THIS pit has already formed the subject of communications to the 

 Society. In one read February 16th, 1863, and in a sub- 

 sequent paper published in the Geological Magazine, Vol. II., 

 p. 529, Mr. Seeley maintained, as- 1 believe Professor Sedgwick had 

 always held, that the singular juxtaposition of Kimmeridge Clay, 

 Cretaceous rocks, and Boulder-clay, was due to faulting. In 1868 

 the Eev. 0. Fisher communicated a paper, in which he accounted for 

 the phenomena, by considering the Cretaceous beds as a huge boulder- 

 like fragment, dropped into a valley which it had excavated in the 

 Kimmeridge Clay, with the intervening space filled up with Boulder- 

 clay. Shortly after this had been read, Mr.. Seeley published a paper 

 in the Geological Magazine (Vol. V., p. 347), in which he attacked 

 Mr. Fisher's view.i The explanation of the phenomena, may there- 

 fore be fairly regarded as still sub judice. During the last three 

 years I have from time to time visited the pit, and purpose to lay 

 before the Society the conclusions at which I have arrived, from re- 

 peated comparison of the rival theories with the sections exhibited 

 during the progress of the works. 



The pit is an irregular excavation with its longer diameter lying 

 roughly East and West, its shorter North and South. The northern 



^ Mr. Fisher's paper was printed subsequently, Vol. V. p. 407. 



