grasslands. Because of its beauty, and because large parcels of 

 high elevation rangeland in good condition are scarce, this RNA is 

 under consideration as a National Natural Landmark (NNL). 



Not far from Cliff Lake RNA is Cave Mountain, a proposed RNA 

 and NNL in the Gravelly Mountains. The Cave Mountain area ranges 

 in elevation from 7,740 to 9,880 feet, and covers 1,800 acres of 

 high subalpine forest and alpine grassland dominated by Idaho 

 fescue ( Festuca idahoensis ). On Cave Mountain, and throughout the 

 Gravelly range, sinkholes or caves were formed by the erosive 

 action of glaciers on the soluble Madison limestone. 



The La Hood Canyon Flat and La Hood Canyon Slope areas on the 

 Jefferson River southeast of Whitehall represent near-pristine 

 rangeland, dominated by bluebunch wheatgrass and needlegrasses. 

 These small parcels of near-pristine vegetation are unique 

 examples of original grassland communities, and can be used to 

 monitor the effects of grazing and farming on rangeland 

 ecosystems . 



Along with its outstanding geologic features, the 2,730-acre 

 Lewis and Clark Caverns State Park contains some of the best 

 examples of dry forest and rangeland in western Montana. The 

 park's forest community is composed of extensive stands of limber 

 pine and Douglas fir. This site also represents one of the few 

 examples of chaparral vegetation in Montana, and includes xeric 

 species such as curlleaf mountain mahogany, big sagebrush and 

 skunkbrush sumac. This natural feature site is considered to be 

 a high priority candidate for NNL designation, due to its unique 

 ecological and geological attributes. 



None of the botanical natural feature sites within these 

 drainages contain any threatened or endangered plants listed by 

 the Montana Rare Plants Project or as candidates for listing by 

 the U.S. Fish and Wildlife Service. If a more extensive survey 

 were conducted, additional rare plants or unique plant communities 

 might be discovered. 



Geologic Features 



The recognition of the Missouri headwaters geologic diversity 

 may be due in part to its proximity to Montana's universities and 

 its use by universities around the country for field courses. 

 Nonetheless, about 12 percent of the Class I and Class II 

 geological sites found in the study area, not including type 

 locations, were found in these drainages. Some of the most 

 interesting sites showing the area's geological diversity, 

 including glacial, structural, erosional, and depositional 

 features, are described below. 



Underneath the ski runs of Big Sky at Lone Mountain, one finds 

 an outstanding example of a rock glacier, consisting of 



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