Ch. X.] ON THE PRIMARY ROCKS. 211 



fore, endeavour, in this discussion, to substantiate our objec- 

 tions to this theory, by appealing step by step to these details, 

 and by numerous references to the labours of various geolo- 

 gists ; and though we should fail in this object, yet we trust 

 that the diligence exercised in order to arrive at the truth, 

 will prove that the objections, though groundless, have not 

 been hastily nor frivolously advanced. 



We must not, however, terminate this description of the 

 primary rocks, without making some allusion to the porphyries 

 and zircon-syenites in the vicinity of Christiania, which have 

 been described by Von Buch as overlying transition slate 

 which contains organic remains. It appears to us, after a 

 careful consideration of the details in the translation of this 

 geologist's work on Norway, that this position of the crys- 

 talline rock is not clearly and satisfactorily demonstrated. 

 The same remark may also be applied to the mass of syenite 

 which is said by Macculloch to rest on fossiliferous limestone 

 in the island of Skye. But even admitting the observations to 

 be correct in both instances, these granitic rocks must be 

 then referred, not to the primary formations, but must be con- 

 sidered as analogous to the eruptions of pyroxenie porphyry 

 at Predazzo. On this view of the subject, these rocks would 

 have the same relations to the primary, that the trap of 

 Scotland has to the hornblendic varieties of granite associated 

 with gneiss, mica-slate, and other crystalline schists : their 

 position and mode of connection with the strata denote them 

 to be eruptive rocks ; and although they resemble in compo- 

 sition some kinds of granite, their geological relations are very 

 different from those which have been described in the pre- 

 ceding pages as belonging to the primary formations. 



