Correspondence. 385 
series, as shown by Brooks, Pumpelly, Irving, and others. It is only 
when Lawson carries the facts of the districts which he has studied in 
detail (about 2 square degrees) over the entire Lake Superior region (30 
or more square degrees), assuming that all of the coarse, banded, in- 
tricately contorted granite-gneiss is of the same age and origin as the 
somewhat regular granite-gneiss with which he is most familiar, and is 
consequently later than the clastic series, that I do not follow him. In 
short I accept the facts of both schools, but decline to apply the facts 
of one to the entire region to the exclusion of those of the other. 
It seems to me that my mistake has been in using the word Coutchi- 
ching to designate the schists of this most ancient schist-gneiss-granite 
complex. To this conclusion I had come before Dr. Lawson's criticism 
was published, and had determined in a forthcoming discussion of the 
pre-Cambrian of America, of which my paper was a condensed state- 
ment of a small part (and therefore gives the evidence imperfectly), to 
discard the term Coutchiching for this place. By thus avoiding the 
implication that the Coutchiching is a part of the basement complex this 
series will be left to fall in its proper place as future investigation 
shows it to belong, and if it proves to belong to this fundamental com- 
plex, Coutchiching will of course apply to its schists. In the mean- 
while there will result no such confusion as has come from the applica- 
tion of Coutchiching to the schistose part of this fundamental complex. 
In this connection the question arises as to the use of the term 
Laurentian. Shall it be restricted to the basement granite-gneiss, or 
shall it include the whole granite-gneiss-schist complex prior to the 
clastic series, or shall it also include the granite-gneiss of later age 
which Foster and Whitney call intrusive, which Rominger calls 
Huronian, and Lawson calls Laurentian, and which he has supposed 
is the only Laurentian? From my point of view it certainly cannot 
be applied to the last class alone, and any one of these usages of it is a 
radical deviation from the original application of the term. Logan's 
descriptions of his typical areas (Ottawa and Grenville), clearly show 
that this Laurentian is largely a bedded series of unquestionable detrital 
origin, consisting in large part of limestones, quartz-schists, quartzites, 
and even conglomerates. But the question as to the proper use of Lau- 
rentian is one which I avoided raising in my paper because I knew it 
was one upon which there would be difference of opinion. Lawson's 
article forces a statement of the question even if space does not permit 
an attempt to answer it. 
Lawson objects to my use of the term Archean. It may be suggested 
in return that if my use of this term is open to criticism, Lawson's use 
of Algonkian is perhaps equally open to attack. This is a term intro- 
duced by the United States Geological Survey as a period term standing 
equivalent to Agnotozoic, proposed by Irving, to include pre-Paleozoic 
clastic series, not of the Lake Superior region alone, but for the whole 
United States; yet Lawson places the whole Algonkian as Paleozoic, 
without any reference in it-, original definition or to its use in previously 
published articles. 
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