Glaciation Flashcards
To get 100% in the upcoming test. (22 cards)
What is igneous rock?
Magma from underground spurts up and hardens. ‘Ingni’ is Latin for fire. This happens when there is a change in tectonic plates and can cause mountains to form.
What is sedimentary rock?
Sedimentary is formed from the compressed remains of eroded rocks, and each layer presses down so that the rock debris is squashed together. They can be found underwater with fossils.
What is metamorphic rock?
Metamorphic rocks have been transformed by extreme heat and pressure from molten rock underground or tectonic plate movement.
What rock is most of Scotland composed of and where?
Metamorphic on most of the islands and the highlands.
What rock is the second most common in Scotland?
Sedimentary on most of the lowlands and part of northern Scotland.
What rock is the least common in Scotland?
Igneous.
What is a glacial period?
An interval of time within an ice age that is marked by colder temperatures and glacier advances.
What is an interglacial period?
An interval of warmer climates between glacial periods.
What causes ice ages?
They are triggered and ended by the slow changes in the Earth’s orbit as well as different concentrations of CO2 in the atmosphere.
How does snow turn into ice?
Layers of newly fallen snow crystals contain about 90% air and little compaction takes place.
The branches of the crystals melt together to form firn which contains 20%-30%.
Continued compaction and freezing/melting forms ice. It contains up to 20% of air in the form of bubbles.
What is abrasion erosion?
When a glacier freezes around pebbles and other stone debris, then moves and grinds on the surface of rocks below, wearing it down.
What is plucking erosion?
Glacial meltwater re-freezes around lumps of cracked and broken rock, and as the glacier moves, it pulls the ice-welded rocks out of the ground
What is freeze-thaw erosion?
Water fills a crack in rock.
A change in temperature makes the water freeze and expand, making the crack wider.
The process repeats with more water.
The crack increases enough to break the rock apart.
What does glacial abrasion make?
It carves marks into the rock below called striations.
How is a corrie formed?
Snow collects into a hollow then builds up and gets squeezed into Neve then ice.
Freeze-thaw weathering enlarges hollow.
Steep cliff formed by plucking.
Rock basin formed by abrasion.
Ice melts to form a tarn in the basin.
Left over rock debris forms scree.
How is an arete formed?
When two corries run back to back. As each glacier erodes either side of the ridge, the edge becomes steeper and narrower.
How is a pyramidal peak formed?
When three or more corries and aretes meet. Glaciers carve put the rocks on the sides and freeze thaw weathers the top of the mountain, creating a sharply pointed peak.
What is a misfit stream?
A river that is either too small or too large to have eroded the valley in which it flows.
How are misfit streams formed?
From a glacier eroding a valley into a wide U-shape and melting until only a little water is left undrained.
How are hanging valleys formed?
When smaller valleys (the hanging valleys) that have been carved from lesser glaciers flow into the main, glaciated valley. These additional glaciers aren’t as powerful, so the valleys aren’t as deep, meaning they ‘hang’ above the main valley’s floor.
What are truncated spurs?
They are ridges descending roughly perpendicular to the valley floor on its sides formed by other glaciers or rivers flowing into the main valley glacier.
What are ribbon lakes?
When bands of hard rock on glacier bottoms abrading soft rock on the valley floor, it creates a deeper trough than usual, which then fills up with water after the glacier retreats (melts).
