the Rockies. The fossil site west of Choteau was recently 

 purchased by the Nature Conservancy. 



Two canyons on the Dearborn River contain rapids in addition 

 to those found in the Sun River Canyon. The upper canyon extends 

 from the national forest boundary to Highway 200, roughly 30 

 miles, and the lower canyon extends 18 miles from Highway 287 to 

 the Missouri River. In the upper reach, the stream meanders 

 through dolomite of the Helena formation. Stromatolites 

 (fossilized algal masses) are exposed in the cliffs. 



Pre-glacial and glacial landscape features more subtle than 

 features associated with mountain building include the Flaxville 

 gravels, an unglaciated gravel remnant exposed at Gilman Hill, and 

 the terminal moraine of the Sun River glacier about three miles 

 north of Gilman Hill. 



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