Erosion and Deposition by

Glaciers

Created By: Belinda Schmahl

Table of ContentsTable of Contents

1.1. Glaciers DefinedGlaciers Defined2.2. Formation of GlaciersFormation of Glaciers3.3. Valley or Alpine GlaciersValley or Alpine Glaciers4.4. Continental Glaciers or Ice SheetsContinental Glaciers or Ice Sheets5.5. Glacier MovementGlacier Movement6.6. Glacial DepositionGlacial Deposition7.7. Landforms caused by Glacial Landforms caused by Glacial

DepositionDeposition8.8. Landscape FeaturesLandscape Features

Roughly 18,000 yrs ago 30% of the earth’s surface was covered by glaciers.Roughly 18,000 yrs ago 30% of the earth’s surface was covered by glaciers.

This period is known as the GREAT ICE AGEThis period is known as the GREAT ICE AGE

1. Glaciers Defined1. Glaciers Defined A large mass of ice, A large mass of ice,

formed on land by formed on land by the compaction and the compaction and recrystallization of recrystallization of snow, that is snow, that is moving downhill or moving downhill or outward under the outward under the force of gravity.force of gravity.

Formed when Formed when snowfall > than rate snowfall > than rate of meltingof melting

2. Formation of Glaciers2. Formation of Glaciers

Form when average Form when average incoming snowfall> incoming snowfall> than avg. amount than avg. amount lost by melting and lost by melting and evaporationevaporation Snow Snow increases each yearincreases each year– Picture A- FormationPicture A- Formation– Picture B- GrowingPicture B- Growing– Picture C- RetreatingPicture C- Retreating

2. Formation of Glaciers 2. Formation of Glaciers cont..cont..

As snow increases and As snow increases and evaporation occurs ice evaporation occurs ice crystals become crystals become rounded forming rounded forming granular snowgranular snow..

As more snow falls As more snow falls (alternating melting (alternating melting and refreezing and refreezing compacts snow into a compacts snow into a layer called layer called firnfirn grows into solid ice.grows into solid ice.

This diagram shows how the elevation of the snowline changes with latitude. The approximate elevation of the snowline is indicated on this diagram by the white line.

North Pole 75N 60N 45N 30N 15N Equator

6,000m

5,000m

4,000m

3,000m

2,000m

1,000m

Sea Level

SNOWLINESNOWLINE

3. Valley or Alpine Glacier3. Valley or Alpine Glacier

Gravity pulls downward and outward Gravity pulls downward and outward on bottom layerson bottom layers

This type of glacier carves a This type of glacier carves a U U shaped valley.shaped valley.***Remember streams carve a V shaped ***Remember streams carve a V shaped

valleyvalley

U-Shaped ValleyU-Shaped Valley

4. Continental Glacier or Ice 4. Continental Glacier or Ice SheetsSheets

These are very old and thick and These are very old and thick and may cover entire land masses, snow may cover entire land masses, snow is close to sea levelis close to sea level

Moves very slowly because of weightMoves very slowly because of weight When it reaches ocean it can break When it reaches ocean it can break

offoff Icebergs (called Calving) Icebergs (called Calving)– Greenland- 1.7 million square Km (3 Km Greenland- 1.7 million square Km (3 Km

thick)thick)– Antarctica- 12.5 million square Km (5 Antarctica- 12.5 million square Km (5

Km thick)Km thick)

Depth of Greenland & Antarctic Ice SheetsDepth of Greenland & Antarctic Ice Sheets

5. Glacier Movement5. Glacier Movement

Stationary Glacier- When rate of Stationary Glacier- When rate of movement = rate of meltingmovement = rate of melting

Winter- Glacier moves more (WHY???)Winter- Glacier moves more (WHY???)

Summer Glacier moves less and Summer Glacier moves less and appears to move backwards (WHY???)appears to move backwards (WHY???)

6. Glacial Deposition6. Glacial Deposition

The sediment that is deposited by The sediment that is deposited by glaciers is unsorted (Called Glacial till)glaciers is unsorted (Called Glacial till)*Remember that sediment deposited by *Remember that sediment deposited by

water is sorted.water is sorted.

If sediment is transported by melt If sediment is transported by melt water of glacier than it is deposited water of glacier than it is deposited the same as a river would deposit the same as a river would deposit (Sorted)(Sorted)OutwashOutwash

Glacial till - unsortedGlacial till - unsorted

7. Landforms caused by Glacial 7. Landforms caused by Glacial DepositionDeposition

Moraines- Unsorted Sediment along the edge of Moraines- Unsorted Sediment along the edge of the glacier.the glacier.

Terminal Moraine-The furthest point of the glacier Terminal Moraine-The furthest point of the glacier (Long Island)(Long Island)

Erratic- A large rock that looks misplacedErratic- A large rock that looks misplaced Drumlins- Long smooth hills of glacial till, points Drumlins- Long smooth hills of glacial till, points

in direction of glacier movement.in direction of glacier movement. Karnes- melt water from top of glacierKarnes- melt water from top of glacier Kettles- Circular lakes-Ice breaks off and melts Kettles- Circular lakes-Ice breaks off and melts

undergroundunderground Moraine Dammed lake- When a glacial moraine Moraine Dammed lake- When a glacial moraine

blocks a river valley, resulting in a long narrow blocks a river valley, resulting in a long narrow lakes. (Finger lakes)lakes. (Finger lakes)

Moraine/Terminal MoraineMoraine/Terminal Moraine

ErraticErratic

DrumlinsDrumlins

Outwash PlainsOutwash Plains

KarnesKarnes

Kettle LakeKettle Lake

Moraine Dammed LakeMoraine Dammed Lake

8. Landscape Features8. Landscape Features

Cirques- Semi circular shaped Cirques- Semi circular shaped bedrock formed as glacier moves bedrock formed as glacier moves back toward mountain.back toward mountain.

Arêtes- Steep sided bedrock formed Arêtes- Steep sided bedrock formed as glacier retreated in opposite as glacier retreated in opposite direction.direction.

Horns- Where three arêtes meet upHorns- Where three arêtes meet up

ArêteArêteCirque

U-Shaped U-Shaped ValleyValley

Kettle Lake

Drumlins

Esker

Outwash

plain

Glacial Stream

TillMoraine-dammed lake

Terminal Moraine