Glaciers

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Glaciers

• By
• Dylan
• Tony

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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
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Formation of glaciers

• Snowline- The elevation at which snow falls and
  doesnt 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.

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Types of glaciers

• Valley glacier- when ice moves down a valley, the
  larger the surrounding mountains the larger the
  glacier (usually)
• Continental ice sheets- its 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.

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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

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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.

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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

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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 arent visible other times they
  are.

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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

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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

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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.

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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.

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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.

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THE END

• Overall lesson
• Never eat Yellow snow