260 PROF. T. G. BONNEY ON HORNBLENDE-PICRITE. 



is therefore possible that these Anglesey boulders have not been 

 derived from that island or North Wales, as I had anticipated, but 

 from the Bassenthwaite district. In admitting the possibility of this, 

 I should not feel bound to regard them as proofs of the former 

 extension of Cumberland glaciers to the Welsh area, but should con- 

 sider them, like the Criffel and other northern boulders in North 

 Wales and the Midlands, to have been transported by floating ice 

 during the last great submergence. 



Discussion. 



Mr. Hudleston thanked the author for his definition of the 

 exact nature of picrite, and remarked on the high alumina per- 

 centage of the analysis as being inconsistent with the composition 

 of picrite. He thought the original home of these boulders was 

 not the Lake District, but Anglesey, as suggested by the author in 

 his first paper. 



Mr. Teall said that the Inchcolm picrite contains a very variable 

 quantity of felspar. He thought the presence of felspar in greater 

 proportion could therefore scarcely be regarded as sufficient to differ- 

 entiate the Lake-District rock from that of Anglesey. He cited 

 a case of the occurrence of a boulder of faulted slate, evidently from 

 the Lake District, in North Wales. 



Mr. De E.ance cited examples of this rock from several localities 

 in Flint, Denbigh, and Caernarvonshire, in boulder-clays, and asso- 

 ciated with characteristic Lake-District rocks. The faulted-slate 

 rocks of the Lake District were perfectly distinct in colour and 

 other characters from those of North Wales. 



The Author, in reply to Mr. Hudleston, stated that picrite 

 was a very variable rock. He had difficulty in accounting for the 

 high percentage of alumina ; for as a rule he had failed to detect felspar. 

 The Little-Knot rock is quite an exceptional one, as stated by Mr. 

 Clifton Ward. He knew of no example of rocks of the kind in 

 Anglesey. 



