﻿22 FOSSILIFEROUS LIMESTONE EEOM THE NORTH SEA. [vol. lxxii r 



around the British coasts, where the amount of Glacial detritus,, 

 and even far-transported detritus of any sort, is insignificant com- 

 pared with the amount of detritus derived from local submarine 

 outcrops. This seems to be the rule throughout extensive areas 

 on the submerged continental shelf west of the British Isles. The 

 immense burden of gabbro-boulders on the Porcupine Bank is one 

 of many good examples. The Porcupine Bank is some 130 miles- 

 west of the Galway coast, and presumably it consists in large part 

 of a submarine outcrop of gabbro. 1 Submarine outcrops of Creta- 

 ceous and Eocene limestones have been fairly well proved to exist 

 in the English Channel and off the south-western coast of Ireland. 



The present record of a submerged outcrop of supposed Coralline- 

 Crag off the east coast of Scotland was all the more interesting, 

 because it related to an area where a covering of Glacial detritus 

 might be expected. 



Mr. E. A. Marten" understood that the submarine channel from 

 which this and similar specimens had been obtained was well known 

 to the Aberdeen trawlers, and he wished to enquire whether there 

 was any information available as to the current-flow through the 

 channel ; for the current, if a strong one, would tend to remove any 

 marine detritus that would otherwise have masked the outcrop 

 of the rock. It seemed to him that the channel might have 

 formed a part of the old bed of the Rhine when the North-Sea 

 area was land. He hoped that investigations in submarine geology 

 would, in the near future, be facilitated by the use of submarine 

 vessels suitably equipped for the purpose. 



Mr. n. W. Monckton remarked on the great interest of the paper 

 and of the specimens exhibited. He thought that, in the absence 

 of evidence that the specimens were derived from a boulder, it was- 

 safest to assume that the rock had been in situ in the North Sea. 

 The association of forms in the big block did not look like Bed 

 Crag or, for the matter of that, like Coralline Crag. He suggested 

 Diestian as a possible age for the formation in question. 



Mr. G. W. Young enquired as to the condition of the exterior 

 of the specimen. If it had been dragged off an exposed mass of 

 rock in situ, one would expect to find numerous recent marine 

 organisms attached to it; whereas, if it were a boulder from Glacial 

 Drift, this condition would be less likely. 



Mr. W. H. Booth stated that he had himself secured a piece 

 of shell-conglomerate, similar to the piece on the table, from a 

 London borehole. He had always referred it to the Woolwich 

 Beds, but could now state definitely that it had been found below 

 the Thanet Sand. 



The Author replied to the various points raised in the discussion, 

 and thanked the Fellows for the reception of his paper. 



1 See Gr. A. J. Cole & T. Crook, ' Rock-Specimens Dredged from the Floor 

 of the Atlantic, & their Bearing on Submarine Geology ' Mem. Geol. Surv- 

 Ireland, 1910. 



