SAEK, HEEM, AND JEIHOU. 



335 



and schists formerly regarded as metamorphosed sediments are really 

 igneous rocks in which banding has been developed by crush. In 

 the usual fervour of conversion some writers seem rather desirous, if 

 they can, to account for everything this way. It may be a useful 

 warning that here in Sark we find a series which cannot have been 

 so produced. 



Discussion. 



The Peesident remarked on the value attaching to Prof. Barrois's 

 work in Brittany, and on the interest of the observations made on 

 the country by Prof. Bonney. The conclusions as to the Archaean 

 age of the lower gneissose rocks would probably be generally ac- 

 cepted ; but a question which must still be regarded as an open one 

 was, whether foliation ever corresponded with original bedding. 

 The supposed instances of unconformity and current-bedding de- 

 pended on the assumption that such was the case. 



Mr. Beckee said that certain rocks of California which he had 

 studied were of IS[eocomian age and sedimentary origin, and, despite 

 a certain dissimilarity, there was a remarkable petrographical re- 

 semblance. Amphibolites and other metamorphic rocks were 

 common, and diabases and diorites abounded. The diorites passed 

 into amphibolites ; glaucophane occurred in the latter, and glauco- 

 phane-schists resulted from altered shales, the positions of the 

 glaucophane-prisms resulting from schistosity of the shales and 

 being related to the original bedding-planes. He had remarked 

 transitions between glaucophane and actinolite. 



Mr. Hutley remarked on the probable extension in former times 

 of Archaean, Cambrian, and Silurian rocks from Brittany and the 

 Channel Islands through Devon and Cornwall and Wales. He 

 considered that there might be cases in which foliation denoted 

 original bedding, as in one of the instances suggested by Mr. Hill, 

 in which it seemed that the hornblende-schist might consist of 

 materials derived from the degradation of eruptive rocks. The later 

 stresses in these old rocks may have obliterated the evidence of 

 earlier action of the same kind. 



Mr. Hill said, with reference to Prof. Bonney 's remarks on the 

 difficulties found in mapping the region, in which he concurred, that 

 one advantage was the absence of travelled blocks. He remarked 

 on the curious arkose-like appearance of the crushed rocks on the 

 coast south of Quimperle. He quite agreed that there was an 

 ancient Archaean base to the rocks of Brittany. 



Dr. Hices said that in Great Britain gneiss and other rocks of the 

 character of those on the table from Brittany and the Channel 

 Islands were only found in the Archaean series. The most impor- 

 tant question, i. e. as to the age of these rocks, seemed therefore to 

 be completely settled by these researches. He was inclined to doubt 

 whether the supposed false-bedding of Port du Moulin was really 

 due to deposition. He had described certain breccias in Wales 

 that might explain the conditions exhibited by the crushed gneisses 

 described by Prof. Bonney. 



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