HONEYMAN ON THE METAMORPHISM OF EOCKS. 235 



metamorphism was the effect of hydrothermal action under pres- 

 sure — the heat being derived from the source of internal heat, — 

 the pressure being that of superincumbent strata, or of the waters of 

 the ocean. This is the origin of the general metamorphism which 

 I referred to at the outset, to which all the precarboniferous rocks 

 of Nova Scotia and Cape Breton have been more or less subjected. 



I have thus illustrated the subject of my paper, but I have still 

 some observations to make in connection with the trap which has 

 occupied so much of our attention. Passing from the Arisaig Pier 

 in a south-west direction, we reach the junction of the Upper 

 Arisaig Series, with the Lower Carboniferous — to the east of Mc- 

 Ara's Brook. All the interval is covered by the sea, and conse- 

 quently any underlying exposure of trap is obscured. At the junc- 

 tion is the base, and a small part of a great mass of amygdaloid 

 trap, which a few years ago formed a prominent and picturesque 

 feature. This was. then overlying and obscuring the point of 

 junction which is now exposed. The prominent effect of this 

 intrusion is the change of the general direction of the dip of the 

 Upper Silurian strata, and elevation of the overlying and uncon- 

 formable Lower Carboniferous conglomerate. There is a distinct 

 elaty cleavage in the disturbed Silurian strata which is at right 

 angles to the plane of stratification. ( Vide specimen with fossil.) 

 Onward we find it occurring at the mouth of McAra's Brook, and 

 then at intervals in connection with the Lower Carboniferous strata, 

 appearing as if interbedded. At McAra's Brook, at the junction of 

 the Silurian and Lower Carboniferous grits, there is another out- 

 crop of the same trap. We shall leave it here, and return to the 

 trap at Malignant Cove and Brook. 



We have followed the course of the trap dykes on the north of 

 the Upper Arisaig Series. We find another series of outcrops pas- 

 sing along on the south. This first meets the Silurian strata — 

 south from the mouth of Doctor's Brook where the East Branch 

 turns to the south. This brings up the strata of Upper Clinton 

 age with its characteristic fossils ; these have a northerly dip. It 

 passes an insulated patch of Lower Carboniferous strata, consisting 

 of conglomerate and limestone dipping in the same dkection with 

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