Thursday, October 30, 2014
Chief Mountain in Montana, near Glacier National Park.
The Blackfoot name for the mountain is Nínaiistáko ("Great Chief"). It's not clear who the first white person to see the mountain was, but it appeared on British maps as early as 1795. Meriwether Lewis was probably the first white person to get close to it, as all other early descriptions are from quite a distance.
Chief Mountain was formed by the Lewis Overthrust. As the Plate of Juan de Fuca and the Pacific Plate pushed westward against the North American Plate, a gigantic wedge of rock cracked free from the surface of the North American Plate and pushed eastward. As the tension eased, the wedge slipped back into position. But stress worsened again, and the wedge pushed east again. This created the characteristic "waves" of ridges and valleys that form the Rocky Mountain Front in Montana.
Each eastward push of the wedge scraped up incredibly ancient Proterozoic rock, pushing the Cretaceous rock to the bottom and leaving Precambrian rock in the middle. The Proterozoic rock is incredibly hard. As the surrounding, softer rock weathered away, the Proterozoic rock protected that soft rock beneath it.
This has left behind the distinctive Chief Mountain -- which rises 1,500 feet above the surface of the Great Plains. The mountain is notoriously difficult to climb, due to the highly weathered rock face that makes placement of pitons nearly impossible.
Native Americans often climbed Chief Mountain with bison caracasses, and burned them atop the mountain. Chief Mountain was known to tribes as far east as Ohio, and west to the Pacific Coast. It was widely considered to be a sacred place, and to this day thousands of Native Americans travel there each year to burn sweetgrass, place prayer flags, and perform other ceremonies.
In 1992, a large section of the north face came down in a huge landslide. The "hole" it left is visible directly beneath the horizontal snow line.