548 Remarks on Br. Boast's Primary Geology. 



incidentally made, that a comparison of the granitic formation of 

 Cornwall with that of other countries shows that some compounds 

 that are of rare and limited occurrence in the former, are developed 

 elsewhere in extensive masses : as the instances of the binary com- 

 pounds of quartz and mica, and quartz and talc : and vice versa, the 

 porphyritic granites, and porcelaineous protogine, sparingly scattered 

 in other countries, are abundant in Cornwall, as are likewise, in 

 a still greater degree, the shorlaceous varieties of granite, and the 

 binary combinations of quartz and shorl ; facts which point out to 

 us that all well marked compounds of distinct minerals ought to be 

 distinguished by appropriate names, although they may be only 

 known to exist in small quantities. The above specific binary com- 

 pounds are as much entitled to distinct names, as shorl-rock : if 

 they be not required in the one case, neither is it necessary in the 

 other ; so that the terms shorl-rock, hornblende-rock, and others, 

 should be expunged from the geological nomenclature, if this view be 

 persisted in. If the knowledge of the primary rocks be a study 

 worth pursuing, a mineralogical classification must be ultimately 

 adopted : for, accurate details concerning their transitions into each 

 other, and their modes of association, cannot be given on the present 

 system. This topic will be reverted to ; but in passing we cannot 

 help seizing every opportunity to urge the necessity of this reforma- 

 tion, being firmly convinced that no measure will tend more to pro- 

 mote the progress of this department of the science." 



I think the correctness of the above remark will be readily 

 assented to by Indian Geologists, but the question whether 

 such minute descriptive details cannot be made interesting, 

 as well as useful, I must leave for the Zoologist, the Ornitho- 

 logist, &c. &c. to determine. For in the pursuit of these 

 sciences, it appears to me, that a great portion of the interest 

 lies in that minute, and accurate description of details by 

 which species and varieties are distinguished with certainty, 

 although they have never before been seen. 



In the 4th Chapter the primary schistose rocks of Corn- 

 wall are described, and the author commences with the fol- 

 lowing preliminary remarks : — 



