243 



In texture it most resembles the melaphyr of the Village area, 

 but is more slaty in some parts anil, ap[)arently, more crystal- 

 line in others, the ci'ystallization being, perliaps, most marked 

 in the least altered dark or gray variety. A finely porphyritic 

 variety resembling porpliyrite has also been observed. It is 

 especially contrasted with the melaphyr bordering the granite 

 axis by the comparative absence of the amygdaloidal and scoria- 

 ceous characters. Amygdules are often present, usually in 

 small patches, but are mainly small and indistinct, although 

 occasionally very large and conspicuous. They consist partly, 

 as elsewhere, of epidote or epidote and quartz, but chiefly of a 

 pure, dark green chlorite ; more rarely of cleavable calcite. 

 The calcite amygdules have been, superficially, very generally 

 removed through solution, leaving the original steam-holes 

 essentially intact. Chlorite is decidedly the most abundant 

 and characteristic secondary mineral, and epidote, whether dif- 

 fused or segregated is of subordinate importance. 



The melaphyr area, as a whole, may Ije fairly described as 

 quite uniform in character ; and no reasons are a})parent for 

 drawing geological boundaries through it. No intrusive con- 

 tacts have been observed ; but this point will be referred to 

 again in describing the slate. Neither are there any known 

 facts requiring us to refer the melaphyr to different periods of 

 eruption ; although it is, perhaps, doubtful whether so large a 

 body should be regarded as belonging to a single flow. In 

 attempting to settle this point, I have searched without success 

 for some development of the flow structure siitticiently marked 

 to show wliether the melaphyr still retains in the main, as I 

 suppose it does, an approximately horizontal position. Of 

 course, if still horizontal, the thickness is not necessarily great. 

 The only facts which I have observed that seem to have any 

 bearing upon this point are as follows: (1) At the extreme 

 northeast corner of the melaphyr, not only are the ledges 

 mni-ked as sandstone just east of the boundary, on the map, 

 all m(']a[)hyr, but the ledge immediat(?ly within the boundary 



