3 Theories of Glaciation

Orbit ChangeEarth’s orbit changes gradually, turning more elliptical over a cycle that takes 97 000 years. Mid-cycle is the coldest, which is the time when glaciers form.

Axis ChangeIt takes over 41 000 years for the Earth to change the tilt of its axis. The North Pole receives less light, the temperature drops, and glacial ice begins accumulating

Blocked SunThe sun gets blocked by dust in the atmosphere caused by volcanoes or giant asteroids. This prolonged cooling causes and ice age to occur.

Types of Glaciers

Alpine Glaciers These glaciers move from mountains to lowland areas following river valleys. Tributary glaciers flow into a single main river of ice, where the sides and bottom layers move the slowest, while the top and middle layers move the fastest.

Continental GlaciersContinental glaciers are large ice sheets on flat lowland areas. The ice can be about one kilometer thick, and moves very slowly, sometimes as a result of moving alpine glaciers. They leave behind hilly deposits of debris or scoured bedrock. These giant ice sheets weight down on the continent, and after retreating, the continent moves back up (also known as isostatic rebounding)

Glacial Erosion

PluckingRocks attach to the glacier and get ripped away. This process speeds up when melt-water seeps into cracks, freezes, and cracks the rock.

AbrasionPlucked rocks that are attached to the glacier scrape at rock surfaces as the glacier moves.Rock flour: Fine powdery rock material left behind as a result.

Depositional Material

DriftAny deposits left behind by a glacier, often as a result of ice melt, are known as drift.

TillThe unsorted and unstratified material left when glacial ice melts is known as till. This includes rock flour, sand, gravel, and boulders.

OutwashThe well-sorted and stratified material left from running glacial melt-water is known as outwash. The heaviest material deposits first, followed by lighter.

Features

1 Horn2 Cirque3 Arête4 Medial Moraine5 Lateral Moraine6 Crevasses7 Col8 Snout9 U-Shaped Valley

Features

1 Tarn2 Cirque3 Striations4 Truncated Spur5 Hanging Valley6 Bridal Veil Falls

Glaciated Definitions

Horn: A pyramidal peak that occurs when cirque glaciers erode a mountain on multiple sidesCirque: Hillside hollow made from the erosional activity of glaciersArête: Two cirques that erode the mountain between them, forming a sharp ridgeCrevasse: Deep cracks on the glacier’s surface, formed when the glacier moves over uneven rocksCol: A mountain pass that is formed when two cirques erode the arête between themSnout: Glacier’s leading edgeU-Shaped Valley: Shape of a glacial valley; flat bottom and steep sides

Post-Glaciated Definitions

Medial Moraine: A strand of debris going through the middle of a valley because of joining tributary glaciersLateral Moraine: Rock material attached along the glacier’s side that has been ripped from the valley wallsTruncated Spurs: The area where the V-shaped valley cuts off into a U-shaped valleyTarn: Lake that comes about when a cirque gets filled with waterHanging Valleys: Tributary glacial valleys that joined with the main valley glacier, melted away, and were left hanging high at the side of U-shaped valleysStriations: Grooves made in bedrock by abrasion

Features

1 Ground Moraine2 Recessional

Moraine3 Terminal Moraine4 Esker5 Drumlin6 Outwash Plain7 Kettle8 Finger Lake9 Pro-Glacial Lake10 Erratic11 Braided Stream

Glaciated Definitions

Ground Moraine: Debris deposits that were carried by the glacier in its lower ice layersTerminal Moraine: Debris left at the farthest advance of the glacierRecessional Moraine: Debris deposited at the snout when ablation and accumulation are happening at the same timeOutwash Plains: Area where ice melts and the melt-water deposits stratified debrisCrag & Tail: Created when a glacier hits a very hard rock (igneous) and gets stuck on one side of the rock (tail) while the rest of it moves on

Post-Glaciated Definitions

Pro-Glacial Lake: Lake formed when the terminal moraine acts as a natural dam and is filled with melt-waterEsker: Stratified deposits left behind from melt-waterRibbon Lakes: After glaciation, long, narrow gouges fill up with glacial melt-waterKettle Lakes: A chunk of the glacier gets left behind, eventually melts, and fills in its hole to make a lakeDrumlins: Deposits left behind that are hill-likeErratic: A large boulder that is deposited far from where it originated from

Benefits of Glaciers

Freshwater Melt-water is freshwater and is left in large quantities. It is drinkable and also provides animals with habitats.

HydroelectricityDamming tarns allows for a renewable source of energy.

TourismGlaciers attract people for sight-seeing and recreation, which earns the economy some revenue.

ConstructionLarge deposits of sand and gravel are left behind by glaciers which can be used to build roads.

FarmingGlaciers leave behind minerals and rich soil for farming and grazing (Prairies).

Disadvantages of Glaciers

FloodingWhen glaciers melt, they can cause floods. Excessive melting can lead to the ocean level rising and coastal cities getting submerged.

TemperatureGlaciers make global temperatures more extreme. Also, the sun reflects off of the ice, which heats the planet

Freshwater in OceansSome animals are unable to survive in freshwater when it melts off a glacier and enters the ocean

CrevassesHumans and animals can fall into and become trapped in crevasses

Loss of FreshwaterClean drinking water goes to waste when glaciers melt into the ocean.

ProjectsTeachers have reason to give their poor students more projects to work on (although this was a good project!)