1808.] PniLLTPS IIESSLE DRIFT. . 251 



Dr. Bucklantl popularized this idea, and, under the title of " diluvial " 

 deposits, presented a great number of important observations relating 

 to the final operations on our land of the waters of the sea, followed 

 by river-floods and ordinary atmospheric action*. 



Modern research has convinced us that, instead of that diluvial 

 accumulation being the work of one transitory and confused dis- 

 turbance of the level of sea and land, there were successions of 

 drifted deposits, under different conditions, having unequal distribu- 

 tions, and peculiar local directions. We have not merely translated 

 the antique " diluvial " into the modern " drift ; " the abnormal 

 cataclysm has become an intelligible series of local sea-actions and 

 limited displacements of land ; the crisis has become a period : 

 Pregiacial and Postglacial eras are marked in time, and charac- 

 terized by successive races of animal and vegetable residents. 



Those who, like myself, had to struggle with the Boulder-clays 

 and northern drift more than forty years ago, without the aid of 

 glaciers and icebergs, and with no clear theory of the changes of 

 level of land or sea, were apt to leave out of our local descriptions 

 phenomena which seemed merely perplexing, or merely exceptional. 

 Yet we attempted, even then, to express some ideas of the succession 

 among diluvial beds ; and we now recognize in the full descriptions 

 of the cliffs of Yorkshire and Norfolk the facts which we had seen as 

 clearly, but had not been able to enunciate in language suited to 

 their importance, or conformable to modern theory. 



In the notices which have been presented to the Geological 

 Society of late years touching the drift-deposits of the South York- 

 shire coasts, reference is usually made to a description which I gave 

 in 1829, and repeated in 1836, of some shell-bearing gravels near 

 Ridgemontt, and some ossiferous gravels and Boulder- clays at 

 Hesslet. But these descriptions were too brief to give a sufficient 

 idea of what was observed; so that in the former case it does not 

 seem to have occurred to the authors referred to that the shelly gravels 

 were regarded by me as lying in the Boulder-clay series, and were 

 described in this relation by reference to Dimlington, Skipsea, 

 Brandsburton, and Paghill. In regard to the Hessle deposit, it seems 

 desirable to present the original observations, made in April 1826, 

 because, as I am informed, the sections now to be seen in the pits 

 are neither so clear nor so extensive as they were when I first ex- 

 amined them. 



These sections and descriptions are given without any change. 



<* 12 April 1826. 



''Walked to Hessle, &c. The gravel lies over chalk and flint, 

 itself composed of such fragments. 



"(a) Thick bed of brown and blue clay, with chalk, &c. At No. 3, 

 further on, it contains coal, chalk, flints, granites, gneiss, syenite, 

 limestone (red and blue), porphyry, hornstone ; and I found what 

 seemed an elephant's tusk. 



* Reliquiffi Diluvianae, 1823. 



t Geol. of Yorkshire, vol. i. ed. i. p. 52, ed. ii. p. 23. 



+ Ibid. ed. ii. p. 20. 



