Vol. 51.] 'CRUSH-CONGLOMERATES ' OF THE ISLE OF MAN. 599 



Mr. E. T. Newton thought that there was some doubt as to the 

 so-called trilobite being really organic. 



Mr. Marr observed that though somewhat similar results of 

 differential movement had been previously described, the great 

 interest of this case described by the Author was the extensive 

 occurrence of thick masses of a rock simulating a sedimentary con- 

 glomerate over wide areas. He believed that many similar rocks 

 had been mistaken for true sedimentary conglomerates in other 

 areas. He noted the discovery by Mr. Harker and himself of rocks 

 having some resemblance to those described by Mr. Lamplugh, 

 amongst the Ordovician rocks of Lakeland. The resemblance, how- 

 ever, was only a general one. 



Mr. Watts, in reply to Dr. Hicks, pointed out that the two chief 

 reasons for bringing forward this paper were : (1) that the con- 

 glomerate occurred over a wide area, and formed a thick zone, 

 which could be mapped. (2) That the rock was not a mere crush- 

 breccia, but the fragments were often well-rounded. The supposed 

 trilobite found in the talus of a quarry in the breccia was not suffi- 

 cient to destroy all the other evidence. In reply to Prof. Hughes, he 

 stated that the main grit group of the Skiddaw Series was separated 

 from the Slate Series by a mass of intermediate beds, thin grits and 

 slates, and it was these intermediate beds which have become 

 brecciated by the differential movement at the junction of the two 

 types of rocks. In conclusion, he pointed out that it would be 

 necessary to scrutinize carefully certain cases in which the age of 

 an ancient rock had been determined by the evidence of contained 

 fragments alone. 



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