Service and currently under consideration for inclusion as a 

 national natural landmark (NNL). Recognized as the battlefield 

 where Chief Joseph and his Nez Perce tribe fought the U.S. Calvary 

 in 1877, it also possesses the only officially protected wetland 

 and steppe vegetation in the Big Hole Valley. 



Due in part to its geographic isolation, southwestern Montana 

 is botanically unique. This region is considered one of the 

 richest areas in the state for rare plants, and many natural 

 feature sites within this drainage contain regionally endemic 

 plant species. One example is the Bitterroot milkvetch 

 ( Astragalus scaphoides ) , a species threatened by grazing and 

 recommended by the Montana Rare Plants Project. Small populations 

 of this plant are found within the sagebrush grasslands that 

 surround the headwaters of Grasshopper and Horse Prairie creeks. 

 Another regionally endemic species is Lemhi beardtongue ( Penstemon 

 lem hiensi s) , found throughout Lemhi County, Idaho and in small 

 populations, in Montana, along the headwaters of Rattlesnake and 

 Horse Prairie creeks. 



Geologic Features 



Eight percent of the geologic feature sites identified in the 

 Montana Rivers Study, excluding type locations, were found in the 

 Beaverhead and Big Hole drainages. 



The Block Mountain area about 16 miles north of Dillon on the 

 Big Hole River graphically illustrates the folding and faulting 

 processes involved in the development of the Rocky Mountains. The 

 area contains an unusually good exposure of Paleozoic and Mesozoic 

 formations, which have been folded and are cut by thrust faults. 



The Humbug Spires Primitive Area a few miles east of the town 

 of Divide provides an excellent exposure of the Boulder batholith. 

 Here the granite has been eroded into spectacular tall, reddish 

 spires and pinnacles. Such landforms are commonly developed on 

 the Boulder batholith, but in this case, the landforms are 

 exemplary. The area is frequented by rock climbers. 



Not far from Ruby Reservoir south of Alder is an area that 

 produces well-preserved fossil insects. The thin bedded Tertiary 

 shales can be peeled apart to reveal the fossils. The area was 

 mentioned during interviews for the Montana Rivers Study, by 

 several experts from Montana universities and the Museum of the 

 Rockies. 



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