Advertisement Upgrade to remove ads

Glaciers and Glaciation

Basal Slip

__________ is one of the two, major flow mechanisms in a glacier.

The [Milankovitch Theory] explains [cyclical] variations in Earth's [climate] as a result of variations in Earth's rotation and orbit.

The [-----] explains [-----] variations in Earth's [-----] as a result of variations in Earth's rotation and orbit.

True

Arête, horns and U-shaped valleys are erosional features carved from bedrock by glaciers.

Accumulation exceeds wastage

Which one of the following applies to a valley glacier that lengthens (extends its terminus downslope) over a period of many years?

U

A _____ cross-valley profile is typical of canyons and valleys eroded and deepended by alpine or valley glaciers.

hanging

Bridal Veil Falls in Yosemite National Park is an example of a 1.----- valley.

True

Till is an unsorted sediment deposited directly from the melting glacial ice; stream action is not involved.

Smooth, tapering ridge of till; formed and shaped beneath a continental ice sheet

A drumlin is a ____________.

cirque, tan

.----- basin in high, mountainous terrain can often be associated with a body of water called a 2.----- lake.

Terminal Moraine

Deposits of till at the terminus (front) of the glacier

Medial Moraine

Formed by the merging of two lateral moraines at a junction of two valley glaciers.

Lateral Moraine

Ridge of sediment deposited along margin of valley glacier

Kettle

Depressions from a retreating glacier that leaves a large block of ice that subsequently melts.

Valley Trains

Long, narrow deposit of stratified drift from braided melt water streams.

Kames

Conical hills of stratified drift; Originally deposited in a depression on glacier's surface.

glacier

Mass of ice that moves by plastic flow and basal slip

alpine glaciers

Confined to mountain valleys
Flow from high to low elevations
-Can be several kilometers across, 200 km long, and hundreds of meters thick

continental glaciers

vast ,Cover at least 50,000 km2
Also called ice sheets

ice caps

50,000 km2
-Mini ice sheets!

plastic flow

Stress and strain induce permanent deformation and movement
▪Occurs continuously

basal slip

Sliding over the underlying surface
▪Occurs occasionally

firn

Granular type of snow
is compacted and recrystallized to glacial ice

Glacial budget

Balance between expansion and contraction of glacier in response to accumulation and wastage

Zone of accumulation

Where additions exceed losses and surface always covered with snow

Zone of Ablation (Wastage)

Losses exceed additions, from melting, sublimation, calving

Firn limit

Separates zone of accumulation from zone of ablation
▪If moves up the glacier, the glacier is receding
▪If moves down the glacier, the glacier is advancing

plucking

Glacial ice pulls rock from bedrock

Bedrock eroded through abrasion:

Glacial polish
▪Smooth surface
Glacial striations
▪Scratches
Glacial flour
▪Pulverized rocks

Fiords

Glacial troughs full of water
-Usually along seacoast

Hanging Valleys

Tributary valley whose floor is above the main valley
-Often have spectacular waterfalls
-Nevada Falls,Yosemite

Arete

Narrow serrated ridge between two glacial valleys or cirques
-From headward erosion

Horn

Steep-walled pyramid-shaped peak formed by headward erosion of at least three cirques

Till

All sediment deposited by glaciers

Glacial erratics

Rock frags carried from source by glaciers

Stratified drift

Layered, with some sorting

Moraines

Layers or ridges of till

Types produced by alpine glaciers

Lateral Moraine
Medial Moraine

cirque

steep sided, half bowl shaped recess at the head of the glacier

glacial drift

the rock material carried and deposited by glaciers

abrasion

the process whereby rock is worn smooth by the impact of sediment transported by the movement of sediment-laden ice over bedrock

glacial polish

a smooth, glistening rock surface formed by the movement of sediment-laden ice over bedrock

glacial striation

scratch left in the ground by rocks carried by a glacier

end moraine

a ridge/mound of till that forms at the terminus (end) of a glacier

ground moraine

Layer of sediment released from melting ice as a glacier's terminus retreats

lateral moraine

Ridge of sediment deposited along margin of valley glacier

medial moraine

Moraine carried on central surface of glacier
-Formed when two lateral moraines merge

kettles

Depressions from a retreating glacier that leaves a large block of ice that subsequently melts

Drumlins

Elongated hills of till; often in extensive drumlin fields

Outwash plains

Sediment deposited by melt water from glacial terminus

Kames

Conical hills of stratified drift
Originally deposited in a depression on glacier's surface

eskers

Long, sinuous ridge of stratified drift
Deposited by running water in a tunnel beneath stagnant ice

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set