2 G. T\ Wright — Theory of an 



in itself, but as connected with a theory which creates greater 

 difficulties than it explains. 



A- long ago as L874 Mr. Belt* and Mr. Goodchildf sug- 

 gested that the sea shells in question may have been pushed 

 up from the bottom of the sea, like other pebbles, by the 

 advance of the glacial current. In 1881 Mr. Clement Eeid;}; 

 also favored the suggestion, while a little later Prof. H. Car- 

 vill Lewis took up the theory and advocated it with great 

 vigor.§ Prof. Lewis's advocacy is the more significant, in 

 view of the fact that, in the light of his experience in con- 

 ducting with me the survey of the glacial boundary in Penn- 

 sylvania, he had just devoted two years to a survey of the 

 glacial boundary in Ireland, Wales, and England. But his 

 sudden death interrupted both the further field work which 

 he was proposing and the complete digestion and publication 

 of the extensive field notes already taken. 



Investigation, however, has not flagged since Prof. Lewis's 

 death, and the opportunities for collecting additional informa- 

 tion in a visit which I made to England for that purpose last 

 summer, have been largely due to the interest aroused by his 

 work. For the facts now presented I am indebted not only to 

 the papers enumerated below, | but in special degree to the 



* Nature. May 14, 1874. f Geological Magazine, 1874, p. 496. 



% Geological Magazine. 1881, p. 235. 



i5 Proceedings of the British Association for 1886 and 1887. 



|| Dugald Bell, Phenomena of the Glacial Epoch (Transactions of the Geological 

 Society of Glasgow, 1889); J. H. Blake. On the Age and Relation of the so-called 

 "Forest-Bed" of the Norfolk and Suffolk Coast (address at the Anniversary 

 Meeting of the Norwich Geological Society, Nov. 2, 1880); H. W. Crosskey and 

 David Robertson, The Post-Tertiary Fossihferous Beds of Scotland : XV — Jordan- 

 hill Brickworks, and XX — Kyles of Bute (Transactions of the Geological Society 

 of Glasgow, vols, iv and v); H. W. Crosskey, On a Section of Glacial Drift 

 recently exposed in Icknield Street, Birmingham, and Notes on the Glacial Geol- 

 ogy of the Midlands (Proceedings of the Birmingham Philosophical Society, vols, 

 iii and vi) ; J. R. Dakyns, Glacial Deposits north of Bridlington (A Paper read 

 "before the Geological and Polytechnic Society of the West Riding of Yorkshire, 

 J 880); C. E. DeRance, Notes on the Vale of Clwyd Caves (Proceedings of the 

 Yorkshire Geological and Polytechnic Society, 1888); On the Post-Giacial De- 

 posits of Western Lancashire and Cheshire (Quarterly Journal of the Geological 

 Society for February, 1871); J. G. Goodchild, The Glacial Phenomena of the 

 Eden Valley and the Western part of the Yorkshire-Dale District (Quarterly 

 Journal of the Geological Society for February, 1875); Percy F. Kendall, On the 

 Occurrence of Nassa Serrata Brocchi in the Glacial Drift of the North Shore, 

 Ramsey, Isle of Man (Proceedings of the Manx Geological Society, 1889); On the 

 Pliocene Beds of St. Erth (Quarterly Journal of the Geological Society for May, 

 1886); G. W. Lamplugh, On Glacial Shell-Beds in British Columbia (Quarterly 

 Journal of the Geological Society for August, 1886); On the Larger Boulders of 

 Flamborough Head and other parts of the Yorkshire Coast, Parts 1I-IV. (Pro- 

 ceedings of the Yorkshire Geological and Polytechnic Society, 1889 and 1890); 

 Glacial Sections near Bridlington (Proceedings of the Yorkshire Geological and 

 Polytechnic Society, 1882 and 1889; On a Recent Exposure of the Shelly Patches 

 in the Boulder-clay at Bridlington Qua} r (Quarterly Journal of the Geological 

 .Society, vol. xxxvi, p. 515 and xl, pp. 312-328) ^ On Photograph of Cliff-Section 



