304 



identical in character with the biotite gneiss amidst which, 

 the hornblendic and actinolite schist® lie." 



In 1896 Archibald Geikie published a paper "On some 

 Crush-conglomerates in Anglesey." (8) The locality was 

 Llangefni, and the strata which had undergone the change 

 were, originally, shales or mudstones, alternating with bands 

 of hard siliceous grit. Geikie says, "They have been crumpled 

 up and crushed into fragments which have been driven past 

 each other along the planes of movement. Every stage may 

 be traced from a long piece of one of the grit bands down to 

 mere rounded and isolated pebbles of the same material." 



In 1897 Messrs. C. I. Gardiner and S. H. Reynolds 

 described some crush-conglomerates in an inlier of Bala 

 (Ordovician) beds on the Irish coast at Portraine.^^^ The 

 authors state, "The strip of coast which we are describing 

 has been subjected to so much disturbance that conglomerate- 

 like rocks, produced by earth-movements, occur almost 

 wherever the lithological character of the beds admits of their 

 being formed." The authors also attempt to make a 

 distinction between a crush-conglomerate and a thrust- 

 conglomerate. Describing one of such, they say, "These beds- 

 are^ very much faulted, crushed, and folded, and every stage 

 can be traced between a continuous limestone-band and one 

 which has been broken up into small rounded fragments, so 

 as to present precisely the appearance of a conglomerate. To 

 this type of rock we propose to restrict the term 'crush- 

 conglomerate,' applying the term 'thrust-conglomerate' to a 

 conglomerate formed along a thrust-plane." As most crush 

 zones follow some kind of a plane in the direction of a thrust, 

 it is difficult to see how such a distinction can hold good. 



In 1898(10) Professor J. E. Marr described a crush- 

 conglomerate which is of interest as showing features that 

 closely resemble those seen in glacial striations. The bed 

 described had been mapped by the Geological Survey as "the 

 Basement Beds of the Carboniferous System" (possibly 

 Devonian). The underlying Skiddaw Slates, as described by 

 Marr, occur "in a much shattered condition, and are 

 immediately succeeded by about 30 feet of a coarse con- 

 glomerate with red sandstone-matrix, filled with large pebbles 

 (8 inches in diameter). This deposit is roughly stratified, 

 owing to the alternation of bands containing few pebbles with 



(8)Geolog. Mag., 1896, p. 481. 



(9) 'An Account of the Portr-aine Inlier" (Co. Dublin), Quart. 

 Jour. Geolog. Soo., vol. liii., pp. 520-535. 



(10) ''Note on a Conglomerate near Melmerby (Cumberland)," 

 Quar. Jour. Geolog. Soc, vol. Iv. (1899), pp. 11-15. 



