CHAPTER VI. 
RELATIONS OF THE KEWEENAW SERIES TO THE 
ASSOCIATED FORMATIONS. 
SEcTION I. TO THE NEWER FORMATIONS. 
THE Eastern SANpstoNr.—Position and extent of the Eastern Sandstone.—Cambrian age of this sand- 
stone.—Relations between it and the Keweenaw Series on the south side of the Keweenaw Range; 
along the ‘‘South Range.”—Different views as to the relations of the Keweenaw Series and the 
Eastern Sandstone.—The south face of the Keweenaw Range is both a fault line and a line of 
unconformable contact. 
THe WestERN SANpstone.—Position and extent.—Contact with the Keweenawan rocks in Douglas 
County, Wisconsin ; this, also, is both a fault line and a line of unconformable contact.—Its equiva- 
lence with the Eastern Sandstone. 
THE Mississiert VALLEY CAMBRIAN SaNDsTONE.—Relations of this sandstone to the Keweenawan diabases 
in the Saint Croix Valley.—It overlies them unconformably. 
SEcTION II. To THE OLDER FORMATIONS. 
Tar ANnmmikie Group.—At Grand Portage Bay, Minnesota; on Wauswaugoning Bay; on the Lucille 
Islands; on Pigeon Point; on Pigeon River; on the west shore of Thunder Bay; in the interior 
between Thunder Bay and Pigeon River; on the north shore of Thunder Bay ; on the east shore 
of Thunder Bay; at Thunder Cape and to the eastward from there.—Relations of the Animikie and 
Keweenawan in this region.—Summary statement as to the Animikie rocks of the Thunder Bay- 
Pigeon River region.—Views of the Canadian geologists as to the Animikie Group.—The 
Animikie rocks in the Mesabi range of Minnesota; at Pokegoma Falls, on the Mississippi 
River; in the Saint Louis River region of Minnesota.—Relations of the Animikie and Kewee- 
nawan rocks in general; the former are not only a downward continuation of the latter.—The 
Animikie rocks are Huronian. 
THE ORIGINAL HurontAN.—Descriptions quoted from Logan.—Nature of the eruptive rocks of the orig- 
inal Huronian.—Resemblances between the Animikie rocks and the original Huronian. 
THE PENoKee Hurontan.—Descriptive section of the Penokee rocks; Huronian in Barron County, Wis- 
consin.—Resemblances between the Animikie and Penokee rocks; they are the same formation. 
THE MARQUETTE AND MENOMINEE Hurontan.—Relations to the Penokee Huronian; they are the same for- 
mation.—Rocks peculiar to the Marquette and Menominee Huronian, and not found in that of 
the Penokee region.—The hornblendic rocks of the Huronian of the Marquette and Menominee 
regions are suspected to be merely uralitic or altered augitic rocks.—The Animikie Huronian 
and that of the Marquette and Menominee regions are the same formation; the former being un- 
folded, the latter folded. 
CRYSTALLINE SCHISTS OF DOUBTFUL RELATIONS.—Insufficient knowledge of these ancient rocks.—Confusion 
with regard to them in the reports of various geologists.—Folded crystalline schists north of 
Lake Superior, from Nipigon Lake to Vermillion Lake, Minnesota.—The iron-bearing rocks of 
Vermillion Lake; their relations to the Animikie rocks of the Mesabi Range.—Doubtfully related, 
folded crystalline schists of the south side of Lake Superior; of the east side of Lake Superior, 
RELATIONS OF THE KEWEENAW SERIES AND THE HURONIAN IN GENERAL.—Similarity between the basic erup- 
tives of the Huronian and Keweenawan.—Absence of amygdaloids in the Huronian.—Contrast 
between the sedimentary members of the two groups.—Structural relations of the two series of 
rocks.—Close approach to conformity, with an intervening erosion, between the unfolded Huro- 
nian and the Keweenaw Series.—The relations of the Keweenaw Series to the folded Huronian 
schists are not so plain; the folding may have taken place before or during the Keweenawan 
period. 
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