8.3 Glaciers Types of glaciers Alpine Small glaciers that form valleys Ice sheets Enormous glaciers...
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Transcript of 8.3 Glaciers Types of glaciers Alpine Small glaciers that form valleys Ice sheets Enormous glaciers...
8.3 Glaciers
Types of glaciers
AlpineSmall glaciers that form valleys
Ice sheetsEnormous glaciers that can cover entire continents
Glacier FormationDescribe the steps
Thick, dense compacted snowFirn:
Firn compacts into glacial iceGlacial ice:
Advancing: A glacier growing faster than it is melting
Retreating: A glacier melting (receding) at the leading edge faster than its growing. It’s NOT traveling backwards.
Glacier Movements
Plastic Flow
Deep within, there is a huge amount of pressure due to weight of ice pressing down.
50 meters thick of ice creates enough pressure to cause ice to flow through the center of a glacier very slowly.
Describe:
Glacier Movements
Basal Slip
Water beneath glacier acts as a lubricant, so entire glacier can slide. This movement can cause a large crevasse (crack), to form.
Describe:
Rate of movement:
Typically a few meters/ day, but can have faster surges.
Glacial structures from erosionStriation
Long scratch marks found in rocks due abrasion caused by rocks & gravel dragged by glacial movement.
Describe:
U-Shaped ValleysV-shaped valleys that are widened by glaciers.Describe:
Glacial structures from erosionHorn peaks
When several cirques converge, the part that is not cut out looks like a horn sticking out of the ground.
Describe:
Cirques
Valleys that look like giant armchairs because they have 3 steep sides & one open side.
Describe:
Glacial structures from erosionFjords
Very steep inlets to the ocean.Describe:
Roche moutonnees
Landforms w/ 1 rough side & 1 side that has been abraded smooth.
Describe:
The coarsely graded sediment deposited by glaciersDescribe:
Till
Unsorted glacial sedimentDescribe:
Glacial Drift
Big rocks deposited by a glacier into an area w/ a different type of rock.
Describe:
MorrainesPiles of boulders, rocks, pebbles, & clay left behind by a glacier.
Describe:
Structures FormedGlacial Erratics
form at the edge of glaciers.Describe:
DrumlinsSmooth, egg-shaped hills left behind by continental ice sheets.
Describe:
Structures FormedTerminal Moraines
Deposits left by melted water coming off a glacier.Define:
kettlesWhen large blocks of ice get trapped under stratified drift, the ice melts and leaves large holes.
Describe:
Stratified Drift
Structures Formed:
Describe: Winding ridges of sand & gravel left behind by receding glaciers.
Eskers
Earth’s OrbitChange in Earth’s orbit around the sun cause slight temperature variations.
Effects:
Effects: The tilt of Earth’s axis changes over time & can affect the amount of sunlight reaching different parts of earth.
Precession