Editing Scree (section)

==Interaction with glaciers==
Scree often collects at the base of [[glacier]]s, concealing them from their environment. For example, [[Lech dl Dragon]], in the [[Sella group]] of the [[Dolomites]], is derived from the melting waters of a glacier and is hidden under a thick layer of scree. Debris cover on a glacier affects the energy balance and, therefore, the melting process.<ref>{{Cite book|last1=Benn|first1=D. I.|title=Glaciers and Glaciation, 2nd ed.|last2=Evans|first2=D. J. A|publisher=Hodder-Arnold|year=2010|isbn=9780340905791|location=London}}</ref><ref name=":3">{{Cite journal|last1=Nakawo|first1=M.|last2=Young|first2=G.J.|date=1981|title=Field Experiments to Determine the Effect of a Debris Layer on Ablation of Glacier Ice|journal=Annals of Glaciology|language=en|volume=2|pages=85–91|doi=10.3189/172756481794352432|bibcode=1981AnGla...2...85N|issn=0260-3055|doi-access=free}}</ref> Whether the glacier ice begins melting more rapidly or more slowly is determined by the thickness of the layer of scree on its surface.{{cn |date= November 2024}}

The amount of energy reaching the surface of the ice below the debris can be estimated via the one-dimensional, homogeneous material assumption of [[Fourier's law]]:<ref name=":3" />

<math>Q = -k \left ( \frac{T_s-T_i}{d} \right )</math>,

where ''k'' is the [[thermal conductivity]] of the debris material, ''T<sub>s</sub>'' is the ambient temperature above the debris surface, ''T<sub>i</sub>'' is the temperature at the lower surface of the debris, and ''d'' is the thickness of the debris layer.<ref name=":3" />

[[File:Lech dl Dragon bis.JPG|thumb|right|Scree-covered [[glacier]], [[Lech dl Dragon]], [[Italy]] ]]

Debris with a low thermal conductivity value, or a high [[thermal resistivity]], will not efficiently transfer energy through to the glacier, meaning the amount of heat energy reaching the ice surface is substantially lessened. This can act to [[Thermal insulation|insulate]] the glacier from incoming radiation.{{cn |date= November 2024}}

===Albedo (radiation reflection)===
The [[albedo]], or the ability of a material to reflect incoming radiation energy, is also an important quality to consider. Generally, the debris will have a lower albedo than the glacier ice it covers, and will thus reflect less incoming solar radiation. Instead, the debris will absorb radiation energy and transfer it through the cover layer to the debris-ice interface.{{cn |date= November 2024}}

If the ice is covered by a relatively thin layer of debris (less than around 2 centimeters thick), the albedo effect is most important.<ref name=":4">{{Cite journal|last=östrem|first=Gunnar|date=January 1959|title=Ice Melting under a Thin Layer of Moraine, and the Existence of Ice Cores in Moraine Ridges|url=https://www.tandfonline.com/doi/full/10.1080/20014422.1959.11907953|journal=Geografiska Annaler|language=en|volume=41|issue=4|pages=228–230|doi=10.1080/20014422.1959.11907953|issn=2001-4422|url-access=subscription}}</ref> As scree accumulates atop the glacier, the ice's albedo will begin to decrease. Instead, the glacier ice will absorb incoming solar radiation and transfer it to the upper surface of the ice. Then, the glacier ice begins to absorb the energy and uses it in the process of melting.{{cn |date= November 2024}}

However, once the debris cover reaches 2 or more centimeters in thickness, the albedo effect begins to dissipate.<ref name=":4" /> Instead, the debris blanket will act to insulate the glacier, preventing incoming radiation from penetrating the scree and reaching the ice surface.<ref name=":4" /> In addition to rocky debris, thick snow cover can form an insulating blanket between the cold winter atmosphere and [[Subnivean climate|subnivean]] spaces in screes.<ref>{{Cite journal|last=Wheeler|first=Ralph A.|date=June 1990|title=Spiders Are Spiders…|url=http://dx.doi.org/10.1097/00007611-199006000-00037|journal=Southern Medical Journal|volume=83|issue=6|pages=723|doi=10.1097/00007611-199006000-00037|pmid=2356505|issn=0038-4348|url-access=subscription}}</ref> As a result, soil, bedrock, and also [[Subterranean river| subterranean]] voids in screes do not freeze at high elevations.{{cn |date= November 2024}}