Hummock

From the initiation of the landslide to the final formation, hummocks can be characterized by their evolution, spatial distribution, and internal structure.

[2] They usually develop in fine-grained soils with light to moderate vegetation in areas of low relief where there is adequate moisture to fuel cryogenic processes.

Because hummocks can both form and disintegrate rapidly (well within a human lifetime)[6] they are an ideal landform to monitor for medium range environmental change.

Hummocks may form as a result of clasts migrating to the surface through frost push and pull mechanisms.

They are also known as active hummocks due to the freeze and thaw cycle of the ice lenses that continually occur within the organic layers of their mounds.

[7] Hummock excavation normally reveals a disturbed soil profile, often with irregular streaks of organic matter or other colorations suggesting fluidity at some point in the past.

[3] Debris avalanches are caused by sudden collapses of large volumes of rock from the flanks of mountains, especially volcanoes.

[8] These events are fast-moving, gravity-driven currents of saturated debris that do not necessarily include juvenile material.

In some cases, such as Mount Shasta in California, the amphitheater has been filled in by later volcanic activity and all that remains are the hummocks.

The blocks simply break off the mountain and slide down, completely intact, identifiable because they differ from the surrounding landscape.

[10] The bottom layer of a debris avalanche deposit is the fine-grained matrix which forms due to the shear at the base of the large, turbulent moving mass.