Vol. 54.] 



AND THE CORALLINE CRAG. 



Table (continued). 



331 







Remabks. 



F. 



Sand witli numerous small entire 

 shells and seams of comminuted 

 shells. 



Features common to all parts of 

 the unaltered Crag. 



a. 



Comminuted shells with remains 

 of polyzoa, forming a soft 

 building-stone. 



False stratification and oblique 

 bedding are constant characters. 



Indurated character of polyzoan rock 

 due to infiltration, and not peculiar 

 to the upper part of the Crag. 



False bedding not confined to the 

 upper part of the formation.^ 



H. 



Sand and comminuted shells. 



Possibly an atmospherically-altered 

 condition of the surface of the 

 indurated Crag. 



The term ' zone ' is, I submit, rightly used for a deposit clearly 

 marked out from others, either by the general character of its fauna, 

 or because it represents some important physiographical change in 

 the conditions of any period ; but it conveys a wrong impression 

 when employed for such minor divisions as those of the Coralline 

 Crag, even if they could be shown to be persistent throughout the 

 formation. It may be safely asserted, I think, that no evidence has- 

 been adduced to show that any one of the alleged zones is character- 

 ized by the presence of species which did not also exist at earlier or 

 later periods in the seas of the N'orth of Europe, and which were 

 evidently then appearing for the first time, or disappearing from 

 the Anglo-Belgian basin. 



As the base of the Coralline Crag had been reached at one locality 

 alone, namely, in the Sutton district, it seemed to be of some 

 importance to ascertain by boring not only the total thickness of the 

 formation where it is best represented (that is, in the neighbourhood 

 of Orford), but to acquire some knowledge, if possible, of any lower 

 beds which might be present there. 



The apparatus that I used for boring was, with some modifications 

 suggested by my early failures, that designed by MM. Van den 

 Broeck & Eutot, and described by them in a paper published by the 

 Societe Beige de Ge'ologie.^ It is admirably adapted for rapidly 

 penetrating beds of dry and moderately coherent material. The only 

 part of the Coralline Crag, however, which it is necessary to explore 

 in this way lies below the water-line, the upper part of the Crag 



^ Mr. Clement Eeid considers that the whole of the Coralline Crag is * more 

 or less current-bedded,' Mem. Geol. Surv. 1890, * Plioc. Deposits of Britain/ 

 p. 36. 



» BuU. Soc. Beige de G60I. vol. ii (1888) p. 135. 



