34 



SKETCH OF THE 



included with the granites composed of two ingredients, such an arrange- 

 ment, however, would separate them from the pure hornblende rock as 

 well as from- the hornblende slates, with both of which they are inti- 

 mately connected, and would only lead to confusion. All rocks, there- 

 fore, in which hornblende preponderates, shall be placed under this head. 



Greenstones. — Including greenstones and greenstone slates, or 

 schists. Under this head will be placed only those rocks which resemble 

 the greenstones of the overlying trap formation^ and which have a more 

 homogeneous and earthy aspect than the hornblende rocks. The more 

 distinct varieties of greenstone slate only shall be included in this class — 

 the more indistinct with the argillaceous schists — the phrase approaching 

 to greenstone slate being prefixed. 



Serpentine. — This requires no definition. Mr. Phillips states, that 

 serpentine, which he classes with the submedial rocks, occurs also asso- 

 ciated with gneiss and mica slate. 



Marble. — This Mnil include primitive limestone and primitive dolomite 

 — with these mica, and occasionally other ingredients, may be associated. 



Porphyry.— I have before stated that this name shall be applied only 

 to the well-marked varieties of this rock which occur imstralijied. Indeed 

 the porphyries of this district, may generally be classed with the granites, 

 &c., in which case the term porphyritic shall be prefixed. 



In the above I have only availed .myself of names already in use, 

 and I have avoided, as much as possible, having recourse to those end- 

 less distinctions,- depending on minute shades of difference, which are 

 more in the province of the Mineralogist than the Geologist. If I can 



