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THE GEOLOGY OF MINNESOTA. 



[Galena limestone. 



The weathering and erosion of the Galena and Upper Trenton have left 

 many scenes of picturesque beauty in the county. The following are some 

 of the most noteworthy, Fig. 22 shows the Eagle Rocks, situated in the 

 valley of the south branch of Root river, on sec. 27, Forestville. They stand 

 isolated in the valley, but do not rise higher than the common rocky walls 

 of the valley. 



FIG. 22. EAGLE ROCKS. 



Chimney rock is on the side of the bluft of a ravine, tributary to the 

 south branch of Root river, on sec. 27, Forestville. A crevice, originally 

 due probably to a plane of jointage, enters the rock at a small angle with 

 the face of the bluff, and has been widened by frost and water till it will 

 admit a man. The detached, wedge-shaped mass, has been broken through 



