Deposition Flashcards
What are the 2 categories of depositional landforms?
Sub-Glacial - Formed beneath glacier ice
Ice-Marginal - Formed along margins of glacier
Subglacial landforms
Drumlins
Ice-Marginal landforms
Moraine
Types of moraine
Lateral
Terminal
Hummocky
Recessional
What is the glacial process of picking up + collecting material known as?
Entrainment of debris
Main depositional processes
Lodgement
Ice ablation
Deformation
Flow
General term for deposited material
Glacial till
Ice ablation
Direct release of debris due to melting (Melt out)
Concentrated near snout of stagnant or recessional ice masses
Subglacial + supraglacial ablation
Sub - Melting of basal ice due to geothermal heat
Supra - Solar radiation melts ice surrounding surface + englacial debris
Lodgement
Occurs anywhere beneath glacial ice
Subglacial material becomes lodged in bed due to frictional forces
Load is high, erosive power is less
Lodgement till
Highly compact due to weight of overlying ice at point of deposition
Deformation
Material beneath or in front is unable to resist glacier’s force
Flow
High meltwater content of rock debris causes it to creep, slide or flow during release from ice
Till deposit characteristics
Angular or sub-angular till
Unsorted (Range of sizes)
Mounds + ridges rather than layers
Variety of rock types
Specific deposit characteristics
Supra Ablation - More angular, less rounded
Lodgement - More angular, less rounded
Subglacial clasts - Striations
