The headwaters of Crooked Creek contain Lost Water Canyon, a 

 proposed U.S. Forest Service Research Natural Area (RNA) and 

 candidate for National Natural Landmark (NNL) designation. This 

 is the only botanical natural feature site in this drainage that 

 received a final value rating of Class I. This rugged limestone 

 canyon is located in the southeastern corner of the Pryor 

 Mountains. The proposed RNA covers the entire Lost Water Canyon, 

 1,630 acres in size. The vegetation is dominated by Douglas fir 

 and limber pine, and also contains scattered patches of subalpine 

 fir and alpine meadows. This pristine area contains many features 

 of outstanding quality, such as the eastern-most extension of 

 Douglas fir in Montana. 



Two other proposed RNAs in this drainage are Passage Creek and 

 Palace Butte within the Gallatin National Forest. Passage Creek 

 is an isolated area of subalpine-f ir forest and moist mountain 

 meadows in the Absaroka Mountains. Palace Butte is a near- 

 pristine watershed, located along Hyalite Creek in the Gallatin 

 Mountains, which contains two lakes, a hanging valley and a 

 waterfall. It is covered by subalpine forest and alpine meadows 

 that range from 7,160 feet to 10,333 feet in elevation. 



Geologic Features 



Twelve percent of the Class I or II geologic feature sites 

 identified in the Montana Rivers Study, excluding type locations, 

 were found in the upper Yellowstone Basin. Further study is 

 likely to reveal additional outstanding sites. 



The Beartooth Highway south of Red Lodge crosses a 10,000-foot 

 plateau and the adjacent area is underlain by some of the oldest 

 rock units in the state. These so-called basement complex rocks 

 are thought to underlie most of the younger sedimentary rocks 

 throughout the state. The basement complex consists of 

 metamorphic rocks, extensively altered by heat and pressure from 

 being deeply buried and from mountain-building processes. Hanging 

 valleys, classic U-shaped valleys, cirques, tarns, and horns 

 created by glacial action are all above the tree line and visible 

 from the highway. Hanging valleys are glacial valleys with their 

 mouths at higher elevations than the main or trunk valleys. Both 

 the trunk and side valleys are carved by glaciers, but the much 

 larger glacier in the trunk valley eroded at a faster rate than 

 the glacier in the side valley, leaving a smaller valley hanging 

 above the larger valley. Many glacially carved valleys are noted 

 for their U-shaped cross section. Cirques are steep-walled, half- 

 bowl shaped hollows usually found on a mountain side or at the 

 head of a glacial valley and are carved by glaciers. Cirques 

 often contain small ponds or lakes known as tarns. 



The Pryor Mountains west of the Bighorn River contain a large 

 number of caves in a relatively small area, mostly formed in 

 limestone. The walls of several caves are said to be covered with 



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