COLUMBIA ICEFIELD PARKS CANADA PHOTO Earth’s Frozen Water

Ice Ages  There have been 7 major periods when glaciers covered much of the Earth  Most recent was about 11,000 years ago

Frozen Water  Covers 10% of the Earth  ¾ of the Earth’s water

Types of Frozen Water  Pack Ice  Tightly packed pieces of sea ice  Ice Flows  Small floating ice pieces  Separated from pack ice  Fast Ice  Attached to shore  Iceberg  Chunks of glacial ice that breaks off glaciers  May reach heights of 90 – 150 m above the water  90% hidden beneath the surface  Glacier  Large moving mass of compressed ice and snow

Related Terms  Glaciologist – a person who studies glaciers  Ice Cap – a large dome-shaped glacier that flows outward from it’s centre and covers a large area, especially of land  Ice Field – an upland area of ice that feeds two or more glaciers  Advancing and retreating – movement of glaciers  Arete – a mountain ridge caused by 2 or more glaciers from several directions  Cirques – a bowl shaped by erosion at the start of the valley  Moraine – ridge of material left behind by a glacier

Salinity of Frozen Sea Ice  Depends on the rate of freezing  New ice: between 4-15 ppt  Sea ice is 35ppt  Over time the brine trickles down, salinity decreases  1 year old: relatively pure

Importance of Glaciers  Store a lot of freshwater  Meltwater (glacier run-off) is released in summer  Provide clues to Earth’s history  Core samples show air quality in past

Columbia Icefield  Water from the Columbia Icefield  Helps run hydroelectric plants  Irrigate crops  Water crops  Largest Accumulation of Ice in Rocky Mountains  Athabasca Glacier 6 km 2  Saskatchewan Glacier 12 km 2 

Glacial Movement  Solid weight and pressure of glacier cause the solid ice to act as a liquid and flow  Centre usually moves faster than sides  Sides slowed down by friction of rocks  Move in different ways and different speeds; depends on  Volume of ice  Slope of ground  Slope of upper ice surface  Amount of water in the ice  Amount of debris it is carrying  Temperature  Friction it encounters

How Glaciers Shape the Land  Glaciers change topography by eroding, transporting and depositing rocks and debris  Moves like a bulldozer  Meltwater fills cracks and refreezes causing more rock to split