Ice Flashcards
What are glaciers
They are large rivers of ice that move very slowly
How do glaciers form
Glaciers form when more snow falls than melts each year, then over many years later upon layer of snow compacts and turns to ice
What are the two types of glaciers
Continental glaciers and alpine glaciers
What are continental glaciers
They are the polar caps over Antarctica and the Arctic circle. A continental glacier is spread out over a huge area
What are alpine glaciers/valley glaciers
They are glaciers which form in places with very cold conditions. They are long and narrow. They form in mountains and flow downhill through mountain river valleys
What are the different ways Ice erode
Plucking, abrasion, freeze-thaw
What is plucking in ice erosion
Plucking is when meltwater from the glacier freezes around cracked and broken rock. When the ice moves downhill, the rock is plucked from the back wall and dragged away by flowing ice
What is abrasion in ice erosion
It is when the rock and stones frozen in the base of glaciers scrape the underlying bed rock.
What is freeze thaw in ice erosion
Melt water gets into cracks in the bedrock of the back wall of the glacier. At night the water freezes, expands and causes the rock to widen. Eventually the rock breaks away and falls onto the top of the glacier.
What are the different features of erosion by ice
Cirque, Tarn, Arête, pyramid peak, u shaped valley, hanging valley, truncated spurs and ribbon lakes
How do cirques form
When a round armchair-shaped hollow is carved out near the top of a mountain when glacial ice pulls away from the back wall and starts moving downhill. It plucks rock from the back wall and abrades the hollow, making it deeper.
How do tarns form
When the ice in the cirque melts, it creates a circular lake in the hollow called a tarn
How does an arête form
A sharp edged ridge that remains when a cirque forms on opposite sides of the same mountain
How does a pyramid peak form
A sharp horn is left behind when glaciers have carved out three or four sides of a mountain
How does a u shaped valley form
As a valley glacier flows through a v shaped river valley, it scrapes away the sides of the valley, carving out a u shaped valley with a flat floor and steep sides
How do hanging valleys form
Pre existing tributaries and their valleys are eroded away by the glacier, leaving the tributaries and their valleys high up the steep sides of the glacier. Their river flows into the main valley in a waterfall
How do truncated Spurs form
Where interlocking Spurs existed previously, the glacier moves through the valley, cutting through these ridges, leaving truncated Spurs.
How do ribbon makes form
A long, deep, narrow lake, usually found in the u shaped valley where less resistant rock was eroded by a glacier
How do glaciers deposit materials
As glaciers flow, mechanical weathering loosens rocks on the valley walls. These rocks fall onto the glacier. Glaciers can carry rocks of any size, and for many kilometers over many years. Glaciers deposit sediment when they melt. They drop and leave behind whatever was frozen in their ice, water from the melting ice may form lakes or other water features
What are some features of deposition by ice
Erratic, moraine, drumlin and esker
How do erratics form
Giant rocks carried by glaciers are eventually dropped. These glacial rocks are noticeable because they are huge and usually of a different rock type to the surrounding bedrock
How do moraines form
When Sediment is deposited by the glacier when the ice melts. Ground moraine is a layer of sediment left behind by a retreating glacier . End moraine is a low ridge of sediments deposited at the end of a glacier, it marks the greatest distance the glacier advanced
How does a drumlin form
A long, low hill of sediment is deposited by a glacier. They often occur groups called drumlin fields. The narrow end of each drumlin points in the direction the glacier was moving when it dropped the sediments.
How does an esker form
A winding ridge of sand deposited by a stream of meltwater. Such streams flow underneath a retreating glacier
What is a summit
The top of a mountain
What is a crevasse
A Deep open crack in a glacier
What is glacial erosion
It is erosion caused my moving ice
