GlaciersBy

Dylan&

Tony

Overview

• Describe how Glaciers form.

• Show Types of glaciers.

• explain how glaciers Move.

• Something about snow.

Snowline

Snowfield

Valley glacier

Continental ice sheets

Basal slip

Internal Plastic Flow

Features of glaciers

Erratic

Till deposits

Stratified drift deposition

Yellow snow

Formation of glaciersSnowline- The elevation at which snow falls and doesn’t

melt throughout the year.Snowfield (ice field)- is the accumulation of snow above

the snowline.Firn- a type of ice that is frozen, partially melted and then

refrozen ect.. It was originally snow but do to all the freezing and melting has transformed into ice crystals

In deep regions of snow deposits, the firns are compressed to the point where all the oxygen is pressed out of them and thus they turn blue, the white color returns after that area is exposed to more oxygen for instance if a portion of it were to fracture.

The rate at witch a glacier would grow or shrink is proportional to the rate of snow that is melted and/or evaporated. More snow, less melting= growth… less snow more melting= decrees in size.

Types of glaciers

Valley glacier- when ice moves down a valley, the larger the surrounding mountains the larger the glacier (usually)

Continental ice sheets- it’s a giant sheet of ice, it can occur over oceans. The only two places currently hosting these phenomena are Greenland and Antarctica.

Ice sheets can be extremely thick, for instance in some regains of Antarctica the ice sheet is over four thousand meters thick

Scientists hypothesize that if these two sheets were to melt, the sea level would raise by over 60 meters.

Movement of glaciers

• It is said that some glaciers travel one hundred meters per year, but that is all dependent upon the conditions of the amount of snow fall vs the melting.

• There are two type of glacial movement• Basal slip and internal plastic flow

Basal slip

• Over time the weight of all the ice on top will cause the ice in contact with the group to melt and then the water freezes and the above ice slips over it.

Internal Plastic Flow

• This process is where the ice firns just tumble over each other on the bottom layer of ice.

• Rate of movement is determined by the angle of the slope

Features of glaciers

• Do to all the different stresses a giant mount of moving ice makes, deep cracks can form and they are called crevasses

• Some times they aren’t visible other times they are.

Glacial erosion

Cirque- when a glacier pulls rocks form the floor of the upper valley

• Arêtes- are jagged ridges that form between the cirques

• Horn- when several arêtes join up to form a kind of jagged pyramid

Glacial deposition

• Erratic- when a bolder is transported by a glacier

• Glacial drift-till is made up of jumbled rock

material-Stratified drift is where rock material

has been sorted and deposited

Till deposits

• Landorms built from till are called moraines.

• Lateral moraine- where sediment is deposited on the side of a valley glacier, usually along a ridge.

• Medial moraine- is when two or more valley glaciers meet and there lateral moraines combine

• Ground moraine- any material not picked up by the glacier.

Stratified drift deposition

• Out wash plain- small rock fragments that are some times carried when parts of a glacier melt

• Kettles are formed when glacial ice are is buried in a drift when the drift collapses the indention is still there, they some times form lakes

• Eskers- what the material from the water forms, they can form things that look like raised winding roads.

lakes

• The great lakes were formed by glaciers

• Also most salt lakes were formed by glaciers as well, they initially were not very salty but as time went on and more evaporation occurred, the saltier they got.

THE END

Overall lesson Never eat Yellow snow