What lies beneath the landscape, in the literal sense, is the place where it all begins, and ends, and continues. Soil is the giant recycling center of the planet, turning death back into new life. In the classic soil profile, there is an organic layer on top composed of mostly plant leaves and decayed logs, a layer below leached by water movement and below that an area of chemical accumulation atop the parent pure-mineral material. In Glacier, soils would generally be classified as poor for traditional human uses. The elevation is too high, slopes are too steep, climate is too cool and soils too thin.
Alluvial soils (formed by water movement) comprise 3% of Glacier's soils, wet soils less than 1% percent, glacial and landslide soils 39%, and bedrock soils 55% of the total. The bedrock soils are usually thin and support sparse vegetation. In the alpine tundra areas, intense frost action has formed the soils into parallel turf-banked terraces on gentle slopes, and ice wedge polygons common on arctic tundra. Curiously, plants grow mostly on the sloped sides of the terraces.
One event in the profile of Glacier's soils gives scientists a definite marker to use in aging soil. Seven thousand years ago, Mt. Mazama, a large volcano in the Cascade Range of western Oregon, collapsed in on itself. It left a gaping hole we now call Crater Lake and expelled enough ash to spread worldwide. In Glacier, 600 miles to the Northwest, layers of the bright brown ash are common in the soil profile. Everything above that layer, of course, happened in the last 7,000 years. In one location in the Avalanche Basin, the ash accumulated to a depth of 6 feet.
Did You Know?
Lake McDonald is the largest lake in the park with a length of 10 miles and a depth of 472 feet. The glacier that carved the Lake McDonald valley is estimated to have been around 2,200 feet thick.