Boulder scree landslide on a Scottish mountain side. SCO 8977
Scree formation is commonly attributed to the formation of ice within mountain rock slopes. During the day, water can flow in joints and discontinuities in the rock wall. If the temperature drops sufficiently, for example with the onset of evening, this water may freeze. Since water expands by 9% when it freezes, it can generate large forces that either create new cracks or wedge blocks into an unstable position. Special boundary conditions (rapid freezing and water confinement) may be required for this process to be effective. Freeze-thaw scree production is thought to be most common during the spring and fall, when the daily temperatures fluctuate around the freezing point of water, and snow melt produces ample free water. The efficiency of freeze/thaw processes in scree production is the subject of some debate in the scientific community. Many researchers believe that it is unrealistic to assume that ice formation in large open crack systems can generate large pressures, instead suggesting that the water and ice simply flow out of the cracks as pressure builds.[ Many argue that a frost heaving process, like that known to act in soil in permafrost areas, may in fact play an important role in cliff degradation in cold environments. The lake Lech dl Dragon in the DolomitesScree can conceal a glacier. For example, Lech dl Dragon, in the Sella Group of the Dolomites, derives from the melting waters of a glacier, hidden under a thick layer of scree. The melting process of the underlying glacier is slowed by the protective layer of scree. With sufficient time, a rock slope may become completely covered by its own scree so that production of new material ceases. This slope is said to be mantled with debris.
Size: 6000px × 4083px
Location: Coignafearn, Glen Mazzern, Inverness-shire. Highland Region. Scotland. United Kingdom.
Photo credit: © David Gowans / Alamy / Afripics
License: Licensed
Model Released: No
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