UNITED STATES GEOLOGICAL SURVEY 
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| | LEGEND | SS 
The spaces between the red and orange tines of the map represent approximately, 2500 feet | a | 
Ducknesses of Keweenawan or Copper bearing beds. Where the dip ws high the lines approach, | a ¢ 
d. to extst, He lines are also made | } I 
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and vice-versa. Where thinning of the beds has been prove: 
two or more coalesce into one on this account The red lines 
to approach, and sometimes 
the orange lines the upper Aisin of he serves Sundarty 
| zepresent the lower division 
the blue lines represent the nndatying slates bat incompletely Where fnill the colored | 
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(| 
} | lines are based on observation, where broken thy are more or less hypothetical | 
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The formations newer than the Koweerrawan are colored in order to show to what extent tt 
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passes under ther 
For more complete explanation see chapter KX | 
Lower and Upper Silurian and Devoman Limestone 
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~-| Light Colored Cambrian (Potsdam) Sandstone | 
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Reddish Honzontal Sandstone (downward confinuation of 2) 
Scale smmino or Linch= 31.565 miles 
_FRRMILLION LAKE 
bier 
p/ ISLANDS ~~ 
| Light tars rare 
