552 Remarks on Dr. Boast's Primary Geology. 



now proposed to consider how these stratified and unstratified rocks 

 comport themselves, when more intimately intermixed in the form of 

 beds, dykes, veins and detached portions of various irregular shapes 

 and dimensions." 



After noticing the occurrence of elongated portions of gra- 

 nite imbedded in the schists as " E^an-courses/' the author 

 remarks : 



11 Besides these somewhat regular beds or courses of granitic rocks, 

 irregular masses or bunches of various dimensions also occur in the 

 primary slates. These are particularly abundant near the junction, 

 as is well illustrated on the sea-shore near the village of Mousehole, 

 in Cornwall ; where they are seen to be connected with the slate 

 on all sides, sending out veins, passing into the slate by mineral gra- 

 dations, forming, with portions of the slate, the same concretions, 

 and also containing insulated pieces of slate of different sizes and 

 shapes. It might be contended that these bunches of granite are 

 merely protuberances of the subjacent granite : in some cases, even 

 at Mousehole, they probably are ; but that they are not always so, 

 is demonstrated by the workings of Dolcoath mine, where several 

 of these outlying masses of granite have been found to be perfectly 

 insulated. 



" The granitic rocks are thus disseminated throughout the crys- 

 talline schists, under various circumstances, and in different forms ; 

 so likewise the latter rocks occur in detached portions in the granite 

 not only at the junction, but in the main mass, some distance there- 

 from." 



The author then gives minute descriptive details of the 

 phenomena of granite veins, and thus concludes : 



" In short, wherever granite-veins have been observed at the junc- 

 tion of the granitic and schistose rocks, they exhibit similar phenomena 

 to those of Cornwall. With very little alteration, therefore, we may, 

 with Mr. Carne*, sum up the evidence on this subject in the following 

 manner : — 



* Geol. Trans, of Cornwall, vol. ii. p. 69. 



