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. A 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 errosion 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
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