Glaciation Flashcards
Periods of ice advantages (ice ages) are called?
Glaciations
Warm periods between Glaciations are called?
Interglacial periods
What is a glacier?
A mass of moving ice
Today glaciers cover
1/10 of the worlds surface
High latitude means
The glaciers are closer to the poles and further away from the equator.
High altitude means
Glaciers away from the poles. This type of glacier only exists in mountainous terrain. As long as the mountain is high enough there will even be glaciers close the the equator.
How does a glacier form?
- Snowflakes collect or accumulate in a hollow or in a mountain side.
- More and more snow falls on the flakes increasing the density or weight.
- The increased weight compresses the snow at the bottom into solid ice.
- If the ice does not melt and the snow continues to fall, the ice mass (glacier) will become bigger and heavier. Gravity will cause it to go downhill very slowly.
Advancement means
Accumulation > melting
Glacier retreat means
When more snow melts than falls (ie abrasion) is higher than ablation so the glacier grows.
Frost shattering/freeze they weathering is
A process of erosion where glacial ice freezes onto rocks and, as it moves away, pulls large pieces of rock with it.
How much of the earth’s surface was covered in ice during the last ice age?
30%
Corries or cirques are
Large bowl-shaped hollows in mountainous areas, snow builds up here so they are generally the source of ice for glaciers
An arête is
A narrow knife-edged ridge on the mountain top. Generally form around a corrie.
A pyramidal peak is
When 3 or more corries cut back into the same mountain they leave a pyramidal peak
Moraine is
A type of landform that is created when a glacier deposits the material (fill) that it has been transporting. It is made up of unsorted angular rocks. There are several types of moraine.
Recessional moraine
Marks the interruptions in the retreat of a glacier
Terminal moraine
Is found at the snout and marks the maxi am advantage of a glacier
Ground moraine
Is dragged beneath a glacier and forms part of the valley floor
Medial moraine
Is found in the centre of a glacier
Lateral moraine
Is produced from frost shattering of the valley sides and is carried at the sides of the glacier
Drumlins
Are elongated features that can reach a kilometre or metre in length, 500 metres or so in width and over 50 metres in height
Drumlins are formed of
Till
A group of drumlins are called a
Swarm
What is an erratic?
A boulder that is different to the bedrock on which it is sitting. They have been transported and deposited by a glacier. Therefore erratics are useful indications of patterns of former ice flow.
