Earth:Dead ice
Dead ice is the ice in a part of a glacier or ice sheet that is no longer moving.[1] As the ice melts, it leaves behind a hummocky terrain known as dead-ice moraine. Dead-ice moraine is produced by the accumulation of sediments carried by glaciers that have been left behind from ice melting. Features of such terrain include kettle holes.[2][3] Landscapes forming Veiki moraines in northern Sweden and Canada have been attributed to the erosion of extensive bodies of till-covered dead ice.[4]
Formation
Dead ice is created when a glacier or ice sheet experiences an increase in melting and accumulates debris from various sediment sources. The debris seeps into the ice, effectively covering the surface area.[5] This leads to the affected area becoming mixed with different types of debris, ultimately slowing the glacier's melting rate.[3][5] This process continues over and over, creating layers of ice and debris, until it forms dead ice. Dead ice most commonly occurs on surge-type glaciers that have ceased moving.[5] It can also be found in any stagnant or debris-filled glacier landforms.[6]
Melting
There are two types of ways dead ice can melt: backwasting and downwasting. Backwasting is when the dead ice melts parallel to an ice-wall or ice-cored slope. Backwasting is more likely to occur when an area is fully ice-cored.[6] Downwasting is when dead ice melts at its top and bottom surfaces. Both dead ice melting rates depend on the climate condition of the area it is in; however downwasting has several other factors that contribute to its process.[5] Another factor that affects both melting rates is the type of debris that covers the dead ice.[5]
References
- ↑ "Dead ice". National Snow & Ice Data Center. https://nsidc.org/cryosphere/glossary/term/dead-ice.
- ↑ Whittow, John (1984). Dictionary of Physical Geography. London: Penguin, p. 133. ISBN 0-14-051094-X.
- ↑ 3.0 3.1 Bluemle, John P. "Buried Glaciers and Dead-Ice Moraine". North Dakota Geological Survey. https://www.dmr.nd.gov/ndgs/ndnotes/ndn14_h.htm.
- ↑ Lagerbäck, Robert (1988). "The Veiki moraines in northern Sweden - widespread evidence of an Early Weichselian deglaciation". Boreas 17 (4): 469–486. doi:10.1111/j.1502-3885.1988.tb00562.x. Bibcode: 1988Borea..17..469L.
- ↑ 5.0 5.1 5.2 5.3 5.4 Schomacker, Anders (2008–2011). "What controls dead-ice melting under different climate conditions? A discussion". Earth-Science Reviews 90 (3–4): 103–113. doi:10.1016/j.earscirev.2008.08.003. ISSN 0012-8252. Bibcode: 2008ESRv...90..103S. http://dx.doi.org/10.1016/j.earscirev.2008.08.003.
- ↑ 6.0 6.1 Krüger, Johannes; Kjær, Kurt H.; Schomacker, Anders (2010-01-01) (in en-US), 7 Dead-Ice Environments: A Landsystems Model for a Debris-Charged, Stagnant Lowland Glacier Margin, Kötlujökull, Developments in Quaternary Sciences, 13, Elsevier, pp. 105–126, doi:10.1016/S1571-0866(09)01307-4, ISBN 978-0-444-53045-5, Bibcode: 2010DevQS..13..105K, https://www.sciencedirect.com/science/article/abs/pii/S1571086609013074, retrieved 2023-11-10
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