Glacial erosion processes

Abrasion
1. Material embedded in ice in contact with valley bottom and sides - rubbing away as glacier moves. The debris in the ice acts.
  1. Fine debris smoothes and polishes rock surfaces
  2. Coarse debris may leave scratches on rock suface known as striations (or deeper scratches - grooves).
  3. Glacial debris itself is worn down forming fine material called rock flour.
Plucking
1. Also known as quarrying
2. When meltwater enters joints in rocks of valley floor and sides. Water then freezes again, glacier freezes onto the rock and as glacier advances plucks away rock.
3. Mainly at base of glacier where PMP may be reached, resulting in presence of meltwater through pressure melting.
4. Most effective in highly jointed rocks or where frost shattering has occurred, 'preparing' the rocks.
Rates of glacial abrasion
1. Debris shape and size - larger debris more effective, as is angular debris (pressure exerted on smaller area where rock and debris meet)
2. Ice thickness - greater the thickness, greater pressure exerted on basal debris and greater rate of abrasion. If pressure too great, too much friction and less movement will happen.
3. Relative hardness of particles and bedrock - resistant debris most effective especially on soft bedrock
4. Sliding of basal ice - greater the sliding, more potential for abrasion
5. Basal water pressure - pressure of meltwater vital for abrasion to enable sliding. If water under too much pressure, glacier may be buoyed up and debris not under as much pressure.
6. Presence of basal debris - more debris more abrasion up until point friction takes over. Basal debris needs to be replenished as it gradually gets worn away.

Nächster

Glacial erosion processes

Beschreibung

Zusammenfassung der Ressource

ähnlicher Inhalt

	Erstellt von EmmaSmile vor mehr als 11 Jahre