Processes of glacial transport - The entrainment of debris Flashcards
What needs to happen to rock debris before it can be transported?
Before being transported, rock debris needs to be entrained (picked up) by glacier ice.
Where is the bulk of the material entrained initially derived?
The bulk of the material entrained is initially derived by the direct action of glacial erosion.
Other than the action of glacial erosion, where can the rock debris transported by the masses be derived from?
The rock debris transported by the masses can be derived from other sources as inputs to the system (from weathering, landslides, avalanches).
What is the impact on the ice surface of finer material, such as dust and volcanic ash?
Finer material, such as dust and volcanic ash transported and deposited by wind, can result in both coarse and fine deposits in the ice surface.
Fine particles are incorporated into the ice by which process?
Fine particles are incorporated into the ice by the process of regelation, with the constant melting and refreezing as basal ice flows over an uneven bed, resulting in a layer of regelation ice several centimetres thick containing sand-sized and finer particles.
How might blocks and clasts be incorporated into basal ice?
Blocks and clasts may be incorporated into basal ice by pressure melting.
Which process may entrain large boulders?
Subglacial bed deformation may entrain large boulders.
Where does significant debris entrainment occur?
In spatial terms there is significant debris entrainment in zones of net freezing, but not in zones of net melting.
