Geological Eras

Annotations:

• • lasted 4 billion years (4.6 billion years ago-579 million years ago) • represents 87% of Earth's history

1. Geological Events
   1. Only part of Canada that existed was the Canadian Shield
   2. The Shield consists of mainly igneous and metamorphic rocks
2. Biological Events
   1. Single-celled organisms; fossils of algae found in rocks, dating to the middle of this period

1. Biological Events
   1. Tropical locations = tropical climates = swamps on the edges of the shallow seas of the Shield
   2. Living organisms developed in shallow seas and swamps
      1. First organisms with shells in the sea; first plant in land
      2. Then came fish in sea; amphibians on land
         1. Fossils of these organisms found in rocks
      3. *Mass extinction is the dividing line between Palaeozoic Era and Mesozoic Era.
         1. Mesozoic Era
            1. Ends with mass extinction. More than 1/2 of the plant and animal species became extinct.
               1. Theory is that it was caused by a collision with an asteriod
         2. End of the Palaeozoic Era saw at least 80% of sea life disappear and many land plants and animals as well -- cause is unknown-- break up of Pangaea, climate change???
2. Geological Events
   1. North America continues to take shape; sediments moved by the rivers and deposited in shallow seas around the Shield
      1. (These were compressed into sedimentary rocks and formed bedrock (solid rock beneath the soil))
   2. 300 million years ago, continents collided to form Pangaea
      1. Caused the Appalachians to form

1. Biological Evenst
   1. Climate is still warm
      1. Reptiles and dinosaurs roamed large swamps and inland seas east of the Rockies (Alberta)
      2. Sea creatures (coral reef) and plants; vegetation in swamps --> as they die, they are covered by sediments and later become oil and coal
2. Geological Evenst
   1. Beginning of the break up of Pangaea
      1. Beginning to form Rocky Mountains (folding) as the Pacific Plate collided with the N. American Plate
      2. New layers of sedimentary rocks

1. Biological Evenst
   1. Mammals (including humans) dominate
      1. Effects on landscape -> dams changed river systems
      2. Effects on biology -> extinction of animals
2. Geographical Events
   1. Final changes to Canada's landforms
      1. Collision of the Pacific and N. American plates caused uplifting to form the Coast Range Mountains; Rockies continue to form
      2. Inland seas disappear as land begins to rise
   2. Glaciation
      1. 4 periods of glacial activity in the last 2 million years (glaciers formed and retreated)
      2. Weight caused them to scrape along the surface; transported material, rounded mountains (the Appalachians) and carved lakes