UNITED STATES GEOLOGICAL SURVEY 
] 93 2 
| DEVONIAN KEWEENAWAN 
at 
||) BBB Pract state BEA y pper division 
ead 
Hamilton group BD Lower division 
SILURIAN HURONIAN 
| a 
ave Helderberg group F | The Original Canadian Huronan 
b Onondaga Se ____ Otherareas in Canada marke as Huronian byBell Most 
cal ondaga Salt: group | vithese areas undoubtedly comprise some true Anronian. 
|r i 5 but ithas not been satisfactorily shown that manyof the sc = “ 
} Niagara group here included do nut rather belong with the older gueisses yi 
| ‘ine ‘> NG] Anima kie or Thunder bay slates of the narth shore Vermillion} 
| | Cincinnati gr EP, (ar | Lake iron bearmg series, and tron bearmg rocks of the S.shore | y 
{zz Trenton group S 
: > Gneiss gramte and crystalline schists Some of the 
CAMBRIAN T | crystalline schists Here included belong with the Hurontan 
but have not been sufficiently separated as yet for 
{ar ] Lower Magnesian limestone mapping . a 
orCalciferous group £ 
(gl Potsdam sandstone of the _t. Dip and strike of inclined strata 
} |i Mississippi Valley {- Strata horzontal or nearly so 
The E pn or La S = > 
pad Peete ay AD fonyectiral positon of the hne between Ue upper 
and lower division of the Keweenaw series. 
VOI | The Western’ Sandstone P 
2,000,000 or T inch = 31585 Miles 
_lepogmphy compiled tron charts of Survey of the Northern and Northwestern Lakes, Land Office 
| Lownsh tp lla Logical Reports: agan and Wisconsiy Maps of the Geological Survey of Canada~ 
Fumers Map higan and Nicodemus &lonovers Map of Wisconstr si : 
Geology based upon naps and reports. CD Jackson, Bela Hubbard, Wihister and J 7) Whitney 
omarige, i Hunpelly, AR. Marvine, TB Brooks, Me wrong, ETS TCthambertin DD Owen | 
nell, 6 Kowvod, ier W Loyan, dlaacuterMurray: omasHao Rurlane and Robert Bell, upon 
MSS notes or Maps by WM Chauvene, A.C Campbell, LAH Chester BN White ana BM hud 
upon miginal observations The correlation of the rocks madang up the older firm ations &s, 
often ortqinad, 
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GEOLOGICAL MAP Qi i: 
