1 Flashcards
UNIT 4
What is Ablation till?
What is it composed of?
Where is this usually found?
Material is deposited due to ablation.
Composed of compacted, unsorted, unstratified material, meltwater removes finer (clay particles)
Found at the snout, ablation occurs, so glacier drops all the sediment, like a conveyer belt
UNIT 4
What is an example of a Kettle Hole?
Caernarfon and Pentir.
Pentir - 75m diameter, filled with hydrophytic plants
UNIT 4
What is Powers scale of roundess when referring to deposits
Sorting
Stratification
Shape
Arrangement of clasts (rock fragments) into similar sizes
Layering of similar sized clasts
Degree of roundness of clasts, (as a result of attrition) (Powers Index of roundness)
UNIT 4
What landforms are deposited by meltwater (fluvioglacial), Where are these found? Why?
Eskers, Kames, Kame terraces, Kettle Holes, Kettle Lakes, Varves. These are found in sandurs, or outwash plains, because the glacier has never reached
UNIT 4
What is fluvial glacial transport?
Transport of debris by meltwater
UNIT 4
What is a push moraine?
What is the orientation of clasts, due to the formation
Glacier advances over existing moraine.
Clasts orientate themselves vertically
Not permanent
UNIT 4
What is an Example of a Drumlin?
Found throughout Conwy valley
UNIT 4
What is a Sandur/Outwash plain?
Flat landscape, formed by fluvioglacial deposition.
UNIT 4
What is a drumlin?
Where/how is it formed?
How can the direction of glacial ice be seen?
Why may it be hard to distinguish drumlins, what is multiple drumlins called?
Elongated hill, streamlined tail.
Formed sub glacially
Fluvial theory - Formed from subglacial meltwater flooding, deposits are then streamlined by glacial ice
Deformational theory - (accepted), glacier moves over an obstacle, till is plastered around it, becoming streamlined
Movement is seen by the direction of the long axis
Vegetation has grown over drumlins, making them harder to see
UNIT 4
How can debris mover from one area to another. What does some of this this depend on?
Supra -> englacial, snow covers supra debris, making it englacial, this causes layers of debris and ice
Englacial -> Supra, glacier melts top layer
Depending on the topography of the ground,
extensional flow, causes debris to flow into crevasses, becoming englacial
compressional flow, sub or englacial material is moved towards the surface (supra)
UNIT 4
What is a lateral moraine?
What margin is it?
How is it formed?
Moraine that forms on the edge of a glacier
Ice-Marginal Landform
Rocks from freeze thaw weathering on rocks above the glacier fall on the sides of the glacier, or debris is wind blown.
UNIT 4
What is an example of a solifluction deposit?
Eglwysbach, just above the village, local material moves downhill
UNIT 4
What is Lodgement till?
What is lodgement till composed of?
How is till orientated?
Till that is plastered into the surface.
Rounded, compacted boulders, matrix of sand, mud and clay.
Orientated facing in one direction, the long axis shows direction of moment (aligned with the ice flow)
UNIT 4
What is a terminal moraine?
How is it formed?
Moraine that marks the furthest advance of a glacier. (Snout)
Glacier has a negative mass balance, so is retreating, causing the deposition of debris and boulders. After the glacier has fully retreated a terminal, crescent shaped moraine is left
UNIT 4
What is an example of a Kame?
Pentir Kame