Editorial Comment. 119 
involved the removal of a large amount of silica and the sub- 
stitution of magnesia and iron oxide throughout large masses 
of rock. This magnesia was found in the silicates and the iron 
oxide was found in the titanic and chromic iron. A slight 
acquaintance with the nature of basic igneous rocks would have 
suggested not only that these elements were indigenous, and 
not secondary in those rocks, but also that the structural condi- 
tions of the formations as well as the chemical combinations 
of these elements could have been due only to a primary origin ; 
and that it was wholly gratuitous and impossible to entertain 
any such metamorphism as they assumed. To a certain extent 
this extreme idea of metamorphism was entertained on the south 
side of the international boundary. Be it said, however, that 
the geologists of the Vermont survey were content to desig- 
nate the kinds of rocks, when they constructed their geological 
map of Vermont, (1861) without assigning to these masses 
any geological age other than "Azoic." Talcose schist with 
some serpentine and much more gneiss and some granite, was 
said to compose the Green mountains of Vermont, these being 
in the direct southward continuation of Sutton mountain. 
T. Sterry Hunt first questioned the post-Potsdam age and 
the metamorphic origin of the Sutton mountain rocks, (1871) 
and Selwyn considered them as probably of the same age as the 
copper-bearing rocks of the region of lake Superior, and of 
like origin (1877). Ebenezer Emmons consistently and uni- 
formly maintained the greater age of the Green mountains, 
but his views, as well as those of Hunt, were overborne and 
out-ruled by officialism and its partisans. 
These remarks are prompted by the article of Prof. J. A. 
Dresser in the July number of the American Journal of Sci- 
ence {A Pctro graphical Contribution to the Geology of the 
Eastern Tozvnships of the Province of Quebec, p. 43) by whom 
the Sutton mountain is regarded not only as of igneous origin, 
blit of pre-Cambrian age. According to his descriptions the rocks 
of the region of Sutton mountain are greenstones, but little ac- 
companied by gneiss, or by quartz porphyry. They lie below 
certain mica schists which contain fragments from them, and 
are much older than the sedimentary portions of the Quebec 
group. They appear hence to be a part of the Archean. 
The tendency therefore has been downward, and since they 
arc new apparently assigned to the x\rchean, it may be that 
