The Big Snowy Group is a stratigraphical unit of Chesterian age in the Williston Basin .
6-639: It takes the name from Big Snowy Mountains in Montana , and was first described on the north slopes of the mountain by H.W. Smith in 1935. The Big Snowy Group is composed of three subdivisions, from top to base: The Big Snowy Group reaches a maximum thickness of 135 metres (440 ft) in the Williston Basin . It is exposed in outcrop in the Big Snowy Mountains , Little Belt Mountains , Castle Mountains and Lombard Hills of central Montana . It occurs in
12-755: A contiguous range immediately to the east. About 112,000 acres of the Big Snowies are roadless, the bulk of this on the Lewis and Clark National Forest , as well as 6,870 acres in the Twin Coulees Wilderness Study Area on adjacent BLM land; 98,000 acres of the National Forest land are also a Wilderness Study Area. The Big Snowies feature a long, relatively level east-west summit ridge, rising above timberline , that culminates in Greathouse Peak,
18-530: Is never summer' ) are a small mountain range south of Lewistown in Fergus County, Montana . Considerably east of and isolated from the main crest of the Northern Rockies , they are one of the few points of significant elevation in the immediate area and are considered one of Montana's island ranges . The range's highest elevation is 8,681 feet (2,646 m). The smaller Little Snowy Mountains are
24-462: The heavily forested north slope, while the south slope is drier. Wildlife includes rattlesnakes and pronghorn on the grass-covered lower elevations and deer and black bear higher up. Crystal Lake is a SNOTEL weather station in the Big Snowy Mountains. Crystal Lake has a subalpine climate ( Köppen Dfc ), bordering on a humid continental climate ( Köppen Dfb ). Lewistown 11 SSE
30-405: The highest point in the range. On a clear day the view from the top of Greathouse Peak extends from Canada to Yellowstone . A number of caves, some unexplored, exist on the west end of the range, including the frozen-walled Ice Cave, which is often up to 40 degrees cooler than outside summer temperatures. The dominant tree species include ponderosa pine , douglas-fir , and subalpine fir on
36-713: The sub-surface throughout the central part of the Williston Basin and into a limited area of south-central Saskatchewan . The Big Snowy Group is unconformably overlain by the Tyler Formation in Montana , and by the Watrous Formation in Saskatchewan ; It disconformably overlays the Madison Group . Big Snowy Mountains The Big Snowy Mountains ( Gros Ventre : níichʔibííkʔa , lit. 'it
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