560 Remarks on Dr. Boase's Primary Geology. 



"5. May not all the phenomena of the primary rocks, both stra- 

 tified and unstratified, be satisfactorily explained on the supposition 

 that these rocks are of contemporaneous origin ?" 



In the 12th Chapter, the subject of "An enquiry into the 

 nature of stratification" is entered upon, in which the various 

 phenomena observed in the primary rocks in various parts of 

 the world, are compared, and the author thus concludes it : 



" We shall, therefore, conclude the chapter, with remarking, 

 that this view not only reconciles many of the incongruous opinions 

 which have been advanced on this subject by the most eminent 

 Geologists ; but it offers us an explanation of those parallel lines 

 which often intersect formations, undoubtedly produced at differ- 

 ent times ; an occurrence that has caused no little perplexity. And 

 lastly, it points out, how a difference of opinion has frequently 

 existed on a subject so apparently simple, as whether a given rock is 

 or is not stratified ; for the term stratum has reference not only 

 to the arrangement of rocks in parallel layers by deposition, but also 

 to the tabular forms produced by joints or seams : and since this is 

 only a variety of structure, common in a greater or less degree 

 to all rocks, it clearly shows that it cannot be made a ground of 

 distinction, much less the fundamental basis for a classification 

 of rocks. The terms stratified and unstratified are, in many respects, 

 synonymous with the two kinds of internal structure, — the massive 

 or compact, and the schistose or fissile : the former predominating 

 in granitic, trappean, and other rocks of this nature, commonly 

 called igneous ; the latter being more characteristic of the primary 

 slates, and of the secondary and tertiary deposits, which are of 

 aqueous origin. We have seen, that though each kind of internal 

 structure respectively prevails in certain series of rocks, yet that 

 neither is exclusively confined thereto : and thus it has happened, 

 that some granitic or unstratified rocks have been pronounced to be 

 stratified ; and some members of the stratified have been called 

 unstratified intrusive masses, though intimately blended with, and 

 perfectly enveloped in, the former. We contend, therefore, that 

 the various kinds of granitic and primary slates have been unneces- 

 sarily separated from each other ; that these slates are not stratified, 



