T B. Brooks—Rocks observed in the Huronian Series. 197 
Lamine of quartz-sandstone occur in magnetite at one local- 
ity, and arenaceous quartzytes ap roaching sandstones at sey- 
eral points. Shaly argillaceous rocks mito! oblique cleavage, 
in places highly carbonaceous, are somewhat common; an 
earthy limonites, having the aace of residual deposits, 
occur in the Marquette Region. These rocks would strictly 
belong in this class, but as their quantity is comparatively 
small, and as they are interstratified with and graduate into 
iiasaorohic. rocks, of which they often appear to be altered 
fos, they are classed below, where they may stand for the 
least metamorphosed varieties of the series. 
2. METAMORPHIC Rocks, NoT CALCAREOUS. 
1. The Mica-bearing Series. 
eu Granite. (L.) Confined to the youngest bed ; also se 
sae in veins in Lower and Upper Hu ronian. Comm 
Pee lpi Semi-porphyritic. 
18, Gro ?—146. Very rare, may exist in the Menomi- 
“© Gneias (L.) Not abundant, mostly associated with 
granite. Common (gray)—zoz. Grani ae Semi-porphy- 
Titic. Compact, related to greenstones— 
(6.) Mica Schist. (L.) Abundant, capectanty 1 in the younger 
rocks of the Marquette Region. Common, blackish and brown- 
Ga taurolitic and holding andalusite (Brush)—6l. 
metiferous—108, 56? nenior Hornblendic—z06 tard 
“6) Mica Slate. fa 58? 
me Hyaro-mica Slate 2—58, 54. Unctuous-feeling, mica- 
‘alle vn ocks, interstratified with iron-ores; they have been 
taleoi schists. Sericite—rz 
a Slate or Argillyte. a. ‘Without gig cotta cleavage. 
tines 7. in independent beds. Chloritie—114? bonaceous 
sabi oo so-called graphitic varieties)—64, 115. Ferruginous, 
mae ated with hematites and limonites. Micaceous, (phyllyte) 
Pyri mi ei to ao (arenaceous obscure varieties)—55 ? 
ith oblique cleavage, conan gener 
— ova 
tal ied sate 2 marbles—118, 20. Roofing 
2. Hornblendic Series. 
pa Syenyte ee quartz). (L.) 
*©00R. Scr.—' Taran Suara, Von. XII, No. 69.—SEPT., 1876. 
