326 MK. J. B. HILL ON THE [Aug. I9OI, 



Although in this particular case the composition of the enclosed 

 boulders might create doubt as to their contemporaneous character, 

 yet if the enclosed boulders happened to be sedimentary (quartzite, 

 for instance, instead of epidiorite), the deformational character of 

 the structure would never be suspected, and the deposit would be 

 classed naturally among the boulder-beds. 



These structures, both in Argyllshire and Cornwall, being evidently 

 related to similar phenomena in the Isle of Man brought to light by 

 the researches of Mr. G. W. Lamplugh, his designation of crush- 

 conglomerate has been adopted for pseudo- conglomerates of this 

 nature. 



[Since Mr. Lampiugh's paper on the ' Crush-conglomerates of the 

 Isle of Man ' in 1895,^ Messrs. Gardiner & Reynolds have described 

 conglomerates of this nature at Portraine in County Dublin,^ and 

 it is interesting to note here that the crush-conglomerate which 

 they describe has been brought about by the breaking-down of a 

 limestone. 



In the Annual Eeport of the Geological Survey for 1895 some 

 remarkable e'xamples of the pseudo-conglomeratic structure among 

 the Lewisian gneiss were described in the ground mapped by 

 Mr. Home in the neighbourhood of Loch Alsh. There a deceptive 

 resemblance to conglomerate has been produced by mechanical 

 movements, and bands of chlorite and actinolite-schist enclose 

 rounded and oval masses of biotite-gneiss and small blocks of 

 quartz. 



Forty years ago Mr. H. C. Salmon, in a paper read before this 

 Society, referred to the fact that the occurrence of boulders and pebbles 

 in the underground working of Cornish mines had long previously 

 been recorded in the Transactions of the Hoyal Geological Society 

 of Cornwall, and he quoted extracts from Messrs. Carne's and Hen- 

 wood's papers. These brecciated rocks occur in a lithological division 

 which I have shown to be very productive of these pseudo-structures. 

 Although these subterranean sections are no longer available 

 for inspection, we may confidently explain their occurrence as crush- 

 conglomerates. Indeed, on the occasion of my reading a paper 

 dealing with these Cornish structures at Penzance last November, 

 Prof. Le jSTeve Foster reminded me of similar phenomena which 

 had always remained a puzzle to the late Mr. W. J. Henwood, 

 in whose company he had seen these underground sections. — 

 June 12th, 1901.] 



Y. Co:ncltjsions. 



The object of this paper has been to show that crush-con- 

 glomerates find their place in the Dalradian Schists of Scotland. I 

 have also shown that they so simulate the appearance of sedimentary 



i 



^ Quart. Journ. Geol. Soc. toI. li (1895) pp. 563-97. 

 ^ Ibid. vol. liu (1897) pp. 527, 531 et seqq. 

 3 Ibid. vol. xvii. (1861) pp. 517-22. 



