GL11 Geomorphic Processes Flashcards
Explain Freeze-thaw weathering and Frost Shattering
- The two types of physical weathering processes are freeze-thaw and frost shattering.
- Freeze-thaw occurs when water enters cracks and expands when it freezes, exerting pressure on the rock, while frost shattering occurs at extremely low temperatures when water trapped in rock pores freezes and expands, creating stress that disintegrates rock to small particles.
What is the process of pressure release?
Pressure release is a type of physical weathering process in which underlying rock expands and fractures parallel to the surface when the weight of overlying ice in a glacier is lost due to melting.
What is carbonation?
- Carbonation is a chemical weathering process in which rainwater combines with dissolved carbon dioxide from the atmosphere to produce a weak carbonic acid.
- This reacts with calcium carbonate in rocks such as limestone to produce calcium bicarbonate, which is soluble.
What is plucking?
Plucking is a process of erosion by glaciers that mainly happens when meltwater seeps into joints in the rocks of the valley floor/sides, freezes, and becomes attached to the glacier. As the glacier advances, it pulls pieces of rock away.
What is abrasion?
- Abrasion is a process of erosion by glaciers in which the debris embedded in its base/sides scours surface rocks, wearing them away. The process is often likened to the action of sandpapering.
- The coarse material will scrape, scratch and groove the rock. The finer material will tend to smooth and polish the rock.
What is till?
- Till is a type of glacial drift, which is material deposited directly by the ice.
- There are two types of glacial till: lodgement till, which is material deposited by advancing ice, and ablation till, which is material deposited by melting ice from glaciers that are stagnant or in retreat.
- Till is typically angular or sub-angular in shape, unsorted, and unstratified.
What is nivation?
- Nivation is a glacial process that includes a combination of freeze-thaw action, solifluction, transport by running water, and possibly chemical weathering.
- It is thought to be responsible for the initial enlargement of hillside hollows and the incipient development of corries.
What is deposition?
- Deposition is the process by which glaciers deposit their load when their capacity to transport material is reduced.
- All material deposited during glaciation is known as drift, which can be subdivided into till and outwash.
- Till is material deposited directly by the ice, while outwash is material deposited by meltwater.
- Glacial deposits currently cover about 8% of the Earth’s surface.
What are the two main processes of glacial erosion?
The two main processes of glacial erosion are plucking and abrasion.
What is drift?
Drift is all the material deposited during glaciation, and can be subdivided into till and outwash.
What is the difference between supraglacial, englacial, and subglacial material?
- Supraglacial material is debris being carried on the surface of a glacier, englacial material is debris within the ice, and subglacial material is debris embedded in the base of the glacier.
What is a drumlin?
A drumlin is a landform created by lodgement till, which is material deposited by advancing ice.
What is the difference between lodgement till and ablation till?
Lodgement till is material deposited by advancing ice, while ablation till is material deposited by melting ice from glaciers that are stagnant or in retreat.
What is nivation?
Nivation is a glacial process that is thought to include a combination of freeze-thaw action, solifluction, transport by running water, and possibly chemical weathering, and is responsible for the initial enlargement of hillside hollows and the incipient development of corries.
What are some sources of material carried by moving ice in a glacier?
Material carried by moving ice in a glacier can come from rockfall, avalanches, debris flows, aeolian deposits, volcanic eruptions, plucking, and abrasion.
