﻿part 1] 



LIMESTONE FROM THE NORTH SEA. 



21 



Fig. 14. Sinodia tertiaria, sp. nov. (See p. 18.) Eight valve, external view. 



15. The same specimen, showing dentition. 



1 6. Wax model of a limestone cavity of another example, with parts of 



both valves in the closed condition. 



17. Tellina benedeni Nyst & Westendorp. (See p. 19.) Internal cast, 



showing features of the pallial line, etc., accompanied by fragments 

 of shell-structure. 



Discussion. 



The President (Dr. A. Smith Woodward) alluded to the 

 interest of the discovery in submarine geology which had been 

 studied with so much care by the Author. So far as could be 

 judged from the accounts of the trawlers, the block of rock 

 was broken from a prominent ridge well known to them. He 

 looked forward to important results from borings in the bed of 

 the sea, which might be obtained by such an apparatus as (he 

 understood) was about to be used by Prof. John Jolj. 



Mr. G. W. Lamplugh congratulated the Author on his very 

 notable addition to our scanty knowledge of the rock-floor of the 

 "North Sea. Geologically, this area was as essentially part of 

 Europe as the land above water, and deserved every possible effort 

 to determine its structure. Much of the Griaeial Drift on the 

 margin of Eastern England had been dragged in from seaward, 

 and gave some indication of the character of the sea-floor. This 

 material included transported patches of early Glacial marine 

 deposits, along with masses of Jurassic and Cretaceous strata ; 

 but in no case had the speaker seen, in the Drifts between the 

 Tees and the Humber, any rock resembling that now exhibited. 

 It seemed unlikely that any bed of rock like that on the table 

 existed beneath the southern part of the North Sea, and the 

 present discovery certainly added a new and important factor to 

 the geology of the whole basin. He would ask whether the 

 Author had considered the possibility that the rock might ori- 

 ginate from a detached mass carried by the ice-flow from the 

 Baltic basin, as the site of the discovery lay in the right position 

 for such transport. 



Mr. T. Crook welcomed this further addition to the record of 

 areas beneath the sea and around the British coasts, where boulders 

 and other masses of rock-detritus are to be found lying on or very 

 near the submarine outcrops from which they have been detached. 

 The fact that these latitudes have been affected by glaciation bas 

 led many to adopt too readily the view that, wherever large boulders 

 occur on the sea-floor, their presence is to be attributed to transport 

 by ice. There are doubtless many glacial erratics on the sea-floor, 

 and in some areas there is apparently an abundance of detritus 

 •of the ordinary Glacial-Drift type— as, for instance, in the almost 

 landlocked Irish Sea, and in parts of the North Sea where one 

 naturally expects to find much ice-carried material. 



For some years past, however, strong evidence has been accumu- 

 lating to show that there are extensive areas beneath the sea 



