Mr. Godwin- Austen's Address, 479 



Bridlington Crag was a name given to a set of marine clay-beds 

 occurring at that place, about 30 feet thick ; they overlie an accumu- 

 lation of chalk flints derived from the subjacent Chalk. 



Mr. S. Wood, in his Monograph, included these beds in the Crag, 

 and considered them the equivalents of the Norwich Crag (1855). 



I am not aware that the fauna of these beds attracted any par- 

 ticular attention till Mr. S. P. Woodward prepared his general list 

 of the Norwich Crag accumulations for Mr. Gunn's essay. In 1864 

 he undertook a fresh examination, not from lists, as before, but from 

 original specimens from Mr. Bean's and Mr. Leckenby's collections ; 

 this led him to the unexpected result that the Bridlington Crag 

 could no longer be considered an equivalent of the Norwich Crag. 

 The list of marine testacea had been increased to 64 (or by more 

 than 20) ; of these, 35 are met with in the Norwich Crag, whilst 29 

 species (or one-half) are now living in seas north of Britain, the 

 proportion of Arctic shells in the Norwich Crag being only one-sixth. 



Mr. Woodward next compared the Bridlington fauna with that of 

 the Clyde beds belonging to the close of the " Glacial period," and 

 with this result, that they differed very nearly as much from these 

 as they did from the Norwich assemblage ; they must therefore be 

 separated from the Crag series. 



The Bridlington testacea are more indicative of Arctic climatal 

 conditions than any assemblage in or about the British Islands. As 

 an assemblage, it is wholly recent and living, and marks a stage in 

 the northern submergence during the Glacial period, when the Arctic- 

 basin marine fauna had extended itself over our seas. 



SHELLS PECULIAR TO BRIDLINGTON. 



Fusus gracilis, var. ventricosus. 

 Trophon clathratus^ L. {Bamffius). 

 liatica occlusa. 



Bowerbankii. 



Trichotropis boreali$. 

 Turritella erosa, Couth, {clathratula). 

 Margarita elegantissima, Bean. 

 Cimoria Noachina. 



Bentalium Tarentinum (entale). 

 Ilontacuta bidentata. 

 Cardita analis ? {borealis}). 

 Astarte borealis, var. semisulcata, 

 Leach. 



mutabilis. 



crebricosta ? 



The Bridlington beds seem to correspond most nearly in age with 

 those which, in Norway, M, Sars has distinguished as his Glacial 

 formation. 



Mr. Trimmer candidly admits that, when engaged in the "Geology 

 of Norfolk" for the Eoyal Agricultural Society (1847), it was the 

 adoption of a theory guiding his observations that enabled him to 

 disentangle and harmonize all that mass of confused materials (Drift) 

 which till then had so perplexed him ; ''each part then soon fell into 

 its appropriate place." In this case, fortunately, the adopted theory 

 was right, namely submergence and emergence — that the accumula- 

 tions of the erratic group indicate a long period of accumulation over 

 a terrestrial surface, followed by denudation as it rose again. For 

 the whole of the period and its products, he proposed two groups of 

 Drift — a lower and an upper. He seems to me to have recognized 

 certain distinctive characters in the Lower Drift, which are the 

 indications of the different conditions of accumulation concerned, 



