a 
Editorial Comment. 49 
gebic, the Marquette, the Crystal Falls, the Menominee, the 
Vermilion and the Mesabi. Monographs on the first three dis- 
tricts have already been published by the United States Geo- 
logical Survey, and a special folio concerning the Menominee 
district has been issued. ‘The details of these districts are the 
same as given in the above-mentioned publications and need not 
be repeated here. There are, however, three new points which 
should be noted—(1) the naming of some of the formations 
which have not heretofore received distinct designations, (2) 
the importance of faults on the Penokee range, and (3) the 
recognition of a sedimentary iron-bearing horizon (not impor- 
tant economically, however,) in the Archean of the Marquette 
district. 
The geology of the Vermillion and Mesabi ranges has not 
been discussed in detail heretofore by the United States Geolo- 
gical Survey, and the present paper contains the results of 
much careful work in these districts. In the writing of the 
descriptions of the Vermilion and Mesabi districts Van Hise 
was assisted by Clements and Leith, respectively, who are en- 
gaged in the preparation of monographs on these ranges. The 
results here presented concerning the stratigraphy of that 
part of Minnesota in which these ranges lie may be summar- 
ized as follows: (1) The presence of three unconformable 
series, which in ascending order are as follows, the names in 
parentheses being those used by the Minnesota survey: the 
Archean (Lower Keewatin), the Lower Huronian (Upper 
Keewatin) and the Upper Huronian (Animikie). (2) In 
each of these series is an iron-bearing formation. (3) The 
iron-bearing formation of the Vermilion range is in the Ar- 
chean (Lower Keewatin), that of the Mesabi range is in the 
Upper Huronian (Animikie), while the iron-bearing formation 
of the Lower Huronian (Upper Keewatin) contains, as far as 
known, no ore deposits of importance. The above results dif- 
fer from the earlier opinions of the geologists of the United 
States Geological Survey in two particulars. First, in the fact 
that formerly the Upper Keewatin and the Animikie were re- 
garded as one and the same series, and, second, in the fact that 
the iron-bearing formation of the Vermilion range was thought 
to be of Lower Huronian age. The present recognition of a 
sedimentary iron-bearing formation unconformably below the 
