392 COPPER-BEARING ROCKS OF LAKE SUPERIOR. 
Feet. 
XIX. Greenstone; aphanitic .--.........---...------ ppNS DUS osacoOdeN Jnon 260 
XX. Covered, but probably dike SXeXs epee eet ee eee eet 525 
XXI. Mica-schist; from aphanitic to medium-grained; including bands of 
light-gray quartz-schist, the mica becoming subordinate; all varie- 
ties having a background of quartz; the mica wholly biotite; pen- 
etrated by veins and masses of very coarse, pink to brick-red bio- 
tite-granite; total on Bad River, 4,960 feet; seen further east, higher 
layers 2,500 feet, in all...-..----.......- BQUBCoHeDS2 Suogsoceuscs 7,460 
otal es/er ce :s.<'esin sielefernves ol ele) eee eee ieee eer 12,800 
Later investigations have shown that some, at least, of the greenstones 
of the above series are diabasic rather than dioritic. 
Here the resemblance to the Animikie rocks is very strong. The 
magnetitic quartzites, other quartzites and quartz-slates, and the argilla- 
ceous slates of the Animikie and Penokee series are identical in character, 
while much of the upper mica-schist member of the Penokee Huronian is 
very close to the mica-bearing quartzite of the Animikie. In each of the 
groups the magnetitic quartzites are near the base of the series, and in both 
there are interstratified greenstone beds. In both, the same relations obtain 
to the newer Keweenawan and older gneisses. The two groups are plainly 
enough the same. 
THE MARQUETTE AND MENOMINEE HURONIAN. 
The iron-bearing schists of the well known iron-regions of the north- 
ern peninsula of Michigan present one point of strong contrast with the 
Animikie Group and the Penokee Huronian, in that, instead of dipping uni- 
formly lakeward, they are closely folded in troughs whose sides are gneiss 
and granite. At first glance, the greater number of rock kinds characterizing 
the Marquette and Menominee Huronian, as compared with that of the 
Penokee region, might seem a further difference. There is, however, so 
plainly a general stratigraphical equivalence between the two series, as I 
have shown elsewhere,' that there can be no doubt of their belonging 
together. There is probably even a direct connection between the two. 
Moreover, the lithological differences in a large measure disappear on closer 
study. According to Brooks* the rocks making up by far the greater part 
1Geology of Wis., Vol. III, p. 163. 
*Geology of Wis., Vol. III, table opp. p. 446. 
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