1/6 The American Geologist. Marcii, isa^ 
also because this paper attempts in part to reconcile conflict- 
ing opinions, it has been thought best to present a brief state- 
ment of the results reached by each investigator. The term 
Keweenawan, as used by the writer, covers the rocks included 
by Irving in this series. At the end of this chapter is a list of 
papers relating to the geology of this area. 
Norwood,' in 1852, gives many details as to the geology 
of the Minnesota coast of lake Superior. Some of the rocks 
were considered to be of igneous origin, but the greater part 
were referred to as metamorphosed sedimentaries. 
Eames," in 1866, mentions trap, greenstone, sandstone 
and metamorphic rocks. 
Kloos,^ in 1871, mentions the gabbro at Duluth and the 
porphyrytes along the Minnesota coast. The same author,' 
in 1871, describes gabbro, melaphyre, porphyries, amygdaloids 
and dike rocks in the vicinity of Duluth; and also,'' in 1877. 
further describes the igneous rocks at Duluth, and shows that 
the melaphyre passes insensibly into the amygdaloids. 
Streng and Kloos," in 1877, give a petrographical de- 
scription of several rocks from Duluth. The igneous rocks 
at the western end of lake Superior are referred to the Pots- 
dam age. 
Winchell (N. H.),' in 1879, refers the igneous rocks 
along the Minnesota coast of lake Superior to the Cupri- 
ferous series. These rocks are associated with extensive 
metamorphic shales, sandstones, quartzytes and conglomer- 
ates. 
Winchell (N. H.),^ in 1880, regards the Cupriferous 
series as Potsdam. The gabbro at Duluth is intimately asso- 
ciated with a metamorphic syenitic granite. All stages of 
metamorphism, from the crystalline granite to the unchanged 
sedimentary layers, were noted. 
Hall (C. W.)," in 1880, finds the Cupriferous series, be- 
tween the mouths of Temperance and Devil's Track rivers on 
lake Superior, to consist of basic igneous rocks and inter- 
bedded strata of sandstone and conglomerate. The Sawteeth 
mountains are due to combined igneous action, the folding 
of sedimentary strata, and erosion. 
Sweet," in 1880, describes the Keweenawan series in the 
vSaint Louis river valley. The eruptive rocks are bedded, 
