234 HONEYMAN— ox THE METAMORPHISM OF ROCKS. 



general characteristics, viz : softness and greasiness ; it is also sus- 

 ceptible of polish, but it soon tarnishes on account of the presence 

 of abundance of minute crystals of sulphuret of iron ? It has slaty 

 cleavage. There is also a considerable thickness of rock, which is 

 more compact. This has been quarried to some extent, with the 

 expectation of obtaining a solid and ornamental stone. In this are 

 transparent veins which have all the appearance of true agalma- 

 tolite. Its next occurrence is at Arisaig Pier, where the finest 

 variety is found. This takes a fine polish and retains it. The 

 only other noticeable rock of the band is on the south of the French- 

 man's barn. It has all the appearance of a serpentine, but it is a 

 green and brown jaspideous rock. 



Overlying this band of metamorphic rocks, is, first of all, fossil- 

 iferous strata of Mayhill Sandstone age — according to Mr. Salter. 

 I regard them as the probable equivalent of the Medina Sandstone of 

 the United States : these are partly arenaceous, sandy, and in the 

 usual condition of strata of this horizon holding fossils ; the only 

 peculiarity is that in the lower parts there is abundance of cubical 

 crystals of iron pyrites. The only obvious consequence of Trap- 

 pean interference is the tilting of the shale. The Lower Clinton 

 shales overlie ; there argillaceous strata have also been disturbed but 

 not hardened, and this is also the case with the other overlying 

 formations. All show the eifects of regional metamorphism, but 

 local metamorphism is confined, to all appearance, to the lowest 

 strata which I have described. By volcanic heat and the presence 

 of the trap which communicated it, aided by the moisture necessarily 

 contained in the strata, rocks have been produced, and minerals 

 which correspond very closely with the crystalline rocks of George's 

 River, Cape Breton. In both there are jaspideous rocks and a 

 mineral not distinguishable from agalmalotite ; the other hydrosili- 

 cate of alumina strata^ show metamorphism equally or nearly so 

 with the hydrosilicates of magnesia, serpentines ; and the want of 

 marble may be in consequence of the absence of fossiliferous lime- 

 stone in the original limestone strata. 



In the case of the metamorphic strata of Cape Breton, the meta- 

 morphism is regional, as at Arisaig, this metamorphism being prior 

 to the eruption which produced the trap there observed. This 



