Editorial Comment. 385 
EDITORIAL COMMENT. 
METAMORPHISM OF THE LAURENTIAN LIMESTONES OF CANADA. 
On the petrographical relations of the Laurentihn limestones and 
the granite in the township of Glamorgan, Haliburton county, Ontario. 
Louis Caryl Graton, (Can. Rec. Sci., vol. i.\, pp. 1-38, Jan., 1903. 
This important paper, prepared under the direction of Dr. 
Frank D. Adams, illustrates and enforces the recent advance 
that has been made in Canada in methods of geological re- 
search. The rocks here treated of (at least the same rock hori- 
zon) have been many times reported on and some old and 
fundamental truths are now confirmed as the result of atten- 
tion and minute field observation, coupled with rational con- 
sideration and microscopical inspection. Some of the new ( ?) 
views are so revolutionary that when applied widely they 
threaten to modify greatly the long accepted classification of 
the Canadian Laurentian, and the "fundamental gneiss" which 
is said to lie at the base. Some of the results may be enumer- 
ated as follows : 
Countless rounded bosses of bare rock, "identical in ap- 
pearance with the fundamental gneiss, have penetrated and 
eaten into the white crystalline limestones'" belonging to the 
Grenville series. 
Dr. Adams has found in recent studies in this area that 
the Grenville limestones, which are always much altered, are, at 
the contact of the "fundamental gneiss," transformed into dark 
basic rocks which still retain the banded structure of the lime- 
stone, in a manner somewhat similar to that described by La- 
croix in the Pyrenees. Here the "fundamental gneiss" contains 
many inclusions of dark basic rock which near the' contact are 
more angular in form, and away from the contact assume the 
form of dark elongated streaks in the "fundamental gneiss." 
The field relations are such that "it seemed practically certain 
that these fragments were portions of the basic contact rock in 
a still more highly altered condition which had floated away in 
the igneous mass during the process of intrusion." At the 
same time there are bands of amphibolyte in the limestone 
away from the intrusions. 
Hence, the alternative questions arise: (1) Has the "fun- 
damental gneiss" been reheated and caused to invade the 
