Crown Butte Preserve
Simms, Montana
The Preserve
Crown Butte rises 900 feet above the foothill prairies just east of Montana’s Rocky Mountain Front. Fortified by tall columns of igneous rock and never cultivated or heavily grazed, the butte serves as an outstanding example of undisturbed native grassland.
Looking west towards the Front Range of the Rockies, wading through the robust native grasses atop the butte, the visitor feels transported in time to an era long before the first wagon train moved west across the prairie.
Geology
Crown Butte is a geological formation called a laccolith. It was formed by intrusions of molten rock, called dikes, which flowed between layers of shale and sandstone that were laid down as marine deposits nearly 80 million years ago. The weak overlying layers bulged upward as the molten rock (magma) intruded, creating the lens-like body of the laccolith. Some of the dikes are visible to the west of Crown Butte, and the soft underlying layers of shale and sandstone are seen at the mouth of the canyon to the south.
After the magma cooled, it formed the resultant rock called shonkinite. Shonkinite is a distinctive rock that contains the glossy black mineral augite, which appears as small stubby crystals. Upon cooling, the rock contracted, causing vertical fractures that formed the towers and columns. While this weather-resistant rock still protects the underlying sedimentary rocks, the surrounding layers have eroded, exposing the butte.
Laccoliths are rare formations, particularly ones with exposed dikes. Crown Butte is one of the finest examples of a laccolith in central Montana and most likely the world.
Wildlife
Although the most striking features of Crown Butte are the rising columns of rock and the wild grasses, the preserve also provides a rich habitat for wildlife. Mule deer are often seen browsing on the summit or along the north slopes of the butte. The loud chants and trills of the rock wren can be heard from every outcrop on the butte. American kestrels, Cooper’s hawks, great horned owls, and prairie falcons hunt the butte, as do golden eagles.
The rocky remains of an “eagle catch” are found on the southeast corner of Crown Butte. Here, within the circle of stones which form the “catch,” native people would hide under branches that they had laid across the top. By placing meat or other bait on the branches they lured eagles to the “catch.” Once the eagles were lured, the natives reached up through the cover of branches and grabbed the legs of the great birds. The eagle’s feathers, considered to be sacred, were then used in clothing, head-dresses and ceremonies.
Vegetation
Crown Butte offers an exceptional opportunity to encounter an undisturbed grassland ecosystem. The four main grassland habitat types are grouped according to dominant plant species. They are: 1) bluebunch wheatgrass/blue grama (on west-facing slopes and on the crest of small knolls); 2) rough fescue/bluebunch wheatgrass (on slightly more moist sites); 3) rough fescue/Idaho fescue (the most productive climax plant community on the butte); 4) Idaho fescue/bluebunch wheatgrass (found less frequently, usually on west-facing slopes, and includes needle-and-thread grass and thread-leaf sedge).
Visiting Crown Butte
Crown Butte is 30 miles southwest of Great Falls. The Preserve can be approached from Simms (on Highway 200, just north of the butte) or from Cascade (on I-15, southeast of the butte). A small parking area is located outside the fence at the south slope of the butte.
From the parking area there is a one-mile trail along the west side of the butte. Elevation is gained gradually to the butte’s base. Along the trail, the careful observer will find a number of tepee rings marked by circles of stones. From the base of the butte to the top, the trail becomes steep for a quarter mile more.
When descending the butte, exercise caution. Watch for snakes. And please . . . no fires, camping, mountain bikes or pets.
