Colum- 
System Series Name poration nar Thickness Character of Rocks 
Name Secti 
ection 
St. Peter Ax o to 75?) Sandstone; white, waterbearing. in hollows of Calciferous dolomite, but absent often 
Ordovician Calciferous 180 § Buff and bluish dolomites often sandy, with dolomitic white sandstones. 
Cambrian 
or 
Primordial 
Huronian 
ILaurentian 
Neo-Cambrian 
Saratogan 
(Potsdam) 
: Upper 
Keweenawan, 
perhaps 
Mio-Cambrian 
(cs 
| 
/ 
) 
Keweena- 
wan 
Lower Ke- 
weenawan, 
perhaps 
e0- 
Cambrian 
Animikean 
neo- Huron- 
jan 
Mio-Huron- 
jan 
Eo- 
Huronian 
Munising 
5 
5 Jacobsville o to r500+ 
a Redstone} (4000 ?) 
& Hiatus not drawn to| 
vo 
c= 
- Freda (goo+) ? 
Nonesuch 350 to 600 
Outer 1200 to 
% 3500 
a 
et 
| 
bs} : 1800 to 
= Lake 400 
iS Shore 2200 to 
Great}#? S40 
2300 to 1417 
1450 to 
2400+ 
(50 sedi- 
ment) 
25000 F 
Me (480 sedi- 
ment) 
? to g500+ 
(500. sedi- 
ment) 
Bohemian 
Range 
1000 tc 4000 
Sandstone; white or light, waterbearing. 
Sandstone: red and brown and striped with streaks of red clay shale, conglomeritic 
where it laps upon older formations. 
scale, the relation of the treda to the Lake Superior Sandstone being uncertain, 
pr obably one formation. 
Sandstone: red, with some felsitic and basic débris, and salt water. 
Shales: dark, fissile beds, with dark basic fragments, and products of decomposi- 
tion of lavas, copper-bearing. 
Conglomerate: very heavy. red, with large rounded bowlders of all lower forma- 
tions, including jaspilitic iron ores, agate amygdules, gabbro aplites, etc. 
Traps: basaltic lavas, and at least one—the ‘‘Middle’—conglomerate. 
Conglomerate: very heavy. like the outer conglomerate. 
Group of basic lava flows. with /requent beds of sediment, Marvine’s (c). 
Group of basic lavas of the ‘‘ashbed”’ type with scoriaceous sediment and only 50 
feet or so of conglomerate. Locally felsites’ 
Group: mainly of lavas of the augitic ophite type, with infrequent sediments. At 
the top is the “Mesnard epidote’’ and just beneath the heaviest flow, over 1.000 
feet thick at times known as the Greenstone. Under thisis the Allouez con- 
glomerate. Maryine’s No. 15. No. 13 is the Calumet and Hecla conglomerate 
or lode. The Kearsarge Lode is shortly above 9. 
Group: mainly of basic lavas. but with intrusive and effusive felsites and coarse 
labrederite porphyrites; also intrusive diabase dikes and gabbro and gabbro 
aplites. 
Slates: black and graphitic, and graywacke slates, passing into graywacke arkoses, 
and quartzites; metamorphosed into staurolite, chiastolite. garnet, and other 
mica schists and phyllitcs. 
Tron formation or schist: slates with cherty carbonate and soft ore. 
Quartzile: with conglomerate base, and above quartzite or red and green flags. also 
volcanic material. 
Iron formation: cherty carbonates, altered to jaspilites, etc., with effusives and 
intrusives altering to hornblende schists and amphibolites. 
Slates: graywackes and arkoses and volcanics. 
Quartzite. 
Slate: black largely. 
Dolomite: with siliceous cherty and slaty (schistose) bands. 
Quartzite: conglomerate and arkose, becoming a seriate schist or gneiss. 
Greenstone schists. amphibolites, hornblende schists, sericite schists or crushed 
felsites, rarely ellipsoidal greenstones and slates and jaspilites, very largely cut 
by granites, the Laurentian, and numerous other classes of injections. 
