Ice Ages

  • Earth has had several ice ages
  • Ice ages are periods of time when freezing temperatures created massive sheets of ice that covered continents
  • The last ice age ended between 6000 and 10,000 years ago
  • During the last ice age, glaciers covered most of Canada and the Northern US

How Ice Ages Occur

  • An ice age occurs when the earth’s climate cools, and snow falling in winter does not all melt in summer
  • Over 1000s of years, the snow builds up and gets so deep it turns to ice- a glacier
  • Glaciers can move very slowly, like a very thick liquid

Types of Glaciers – Alpine and Continental

Alpine Glaciers are smaller glaciers found on mountains

  • They move down valleys because of gravity
  • There are still alpine glaciers in Canada today in the Arctic and in the West Coast Mountains

Continental Glaciers (or ice sheets) are much bigger than alpine glaciers – they can cover entire continent

  • These glaciers move because of their own weight (like pancake batter spreading over the pan)
  • Today, there are only two continental glaciers – over Greenland and Antarctica

Continental Glaciers – Landforms

  • Continental Glaciers make the land smoother by eroding some areas and depositing sediments in others
  • Striations are grooves scraped in rock by rocks frozen in the glacial ice
  • Moraines are large rocks that have been picked up by a glacier and dropped 100s of kilometers away from where they belong
  • Moraines are ridges of sediments and rocks (till) that are pushed along by a glacier and then left behind when it melts
  • Drumlins are egg shaped hills with a steep side and a gentle side
  • The steep side points in the direction the glacier came from

Humans and Glacial Features

  • We use glacial landforms in a number of ways
  • Gravel extraction – we use gravel from glacial till for construction
  • Moraines tend to be used for grazing, forestry
  • Drumlins have deep soil, good for farming

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