GLACIAL LANDSCAPES

GLACIERS

a thick mass of ice that originates on land from the accumulation, compaction and recrystallization of snow

2 basic cycles of glaciers

HYDROLOGIC CYCLE

ROCK CYCLE

How do glaciers form?

-If annual snowfall exceeds melting, snow builds up each season

-as snow is buried, it becomes heavy and gets compacted.

-snow becomes FIRN, an intermediate condition between snow and ice

-FIRN turns into GLACIER ICE under enough pressure

TYPES OF GLACIERS

NOT CONSIDERED BY TOPOGRAPHY:

-Ice Sheets

-Ice Caps

MOUNTAIN GLACIERS:

-Icefield

-Valley glaciers ( Piedmont glaciers, Tidewater glaciers, hanging glaciers)

ICE SHEETS

-Largest type of glacier

-only found in Antarctica & Greenland

-so thick that the bedrock topography is buried

ICE CAPS

A smaller version of ICE SHEET

ICEFIELD

-Looks similar to ice cap

-major difference is its constrained by topographic features

-surrounded by mountains which prevents it from spreading out like an icecap

VALLEY GLACIER

• are confined to valleys between mountains

• look like long tongues of ice

• there are sub types:

  • Piedmont glacier

  • tidewater glacier

  • hanging glacier

PIEDMONT GLACIER

• type of a valley glacier

• forms when a valley glacier spill onto a flat area and spreads out

TIDEWATER GLACIER

• type of valley glacier

• forms when a valley glacier ends in an ocean

• KEY WORD : WATER!

HANGING GLACIER

• also a kind of valley glacier

• glacier that end at the edge of a cliff

• its when a smaller valley glacier meets a larger valley glacier

HOW DOES GLACIERS MOVE? whats it reffered to?

PLASTIC FLOW & BASAL SLIP

PLASTIC FLOW

• has little ice movement and erosion

• cold based (polar) glaciers at high latitude (GREENLAND & ANTARCTICA)

• glacial ice remains below zero and stays frozen to bedrock

• internal deformation

BASAL SLIP

• warm based glaciers at lower latitudes BUT HIGHER THAN POLAR GLACIERS!

• ice mass slips along the rock

• Temp at the base of glaciers can raise due to presssure and friction

• more movement and erosion than a polar glacier

ZONE OF FRACTURE

• occurs in uppermost 50 to 60m

• tension causes crevasses to form in brittle ice

• can occur in both cold and warm based glaciers

RATES OF GLACIAL MOVEMENT

its determined by many factors such as:

• precipitation

• ablation

• steepness of ice

• thickness of ice

• permeability

COLD BASED GLACIERS GENERALLY MOVE 1-2cm/day or 0.5m/yr

BUDGET OF A GLACIER

• balance between accumulation of glacier and loss of glacier

ZONE OF ACCUMULATION

the area where glacier forms

ZONE OF WASTAGE (ZONE OF ABLATION)

area where there is a net loss to the glacier due to melting and calving

GLACIAL EROSION

• glaciers are capable of great erosion and sediment transport

• there are 2 ways:

  • PLUCKING (LIFTING ROCKS)

  • ABRASION (ICE ACTS LIKE A SANDPAPER TO SMOOTHEN AND POISH THE SURFACE BELOW)

GLACIAL ABRASION

Produces:

• rock flour

• glacial striations (grooves in the bedrock)

GLACIAL DRIFT

refers to all sediments of glacial origin

TYPES OF GLACIAL DRIFT

TILL (material that is deposited directly by ice)

STRATIFIED TILL (sediments laid down by glacial meltwater)

GLACIAL TILL

Is typically UNSTRATIFIED AND UNSORTED

LANDFORMS MADE OF TILL

MORAINES!

• LATERAL MORAINE

• MEDIAL MORAINE

• END MORAINE

• GROUND MORAINE

DRUMLIN

• smooth, elongated, parallel hill made of TILL

• steep side faces the direction of the movement of ice

LANDFORMS MADE OF STRATIFIED DRIFT

Outwash Plains and Valley trains

TYPES OF GLACIAL DRIFT

TILL

• MORAINES (End, Lateral, Medial)

• DRUMLINS

STRATIFIED DRIFT

• OUTWASH PLAINS
  ICE CONTACT DEPOSITS ( Kames, Eskers)