Earth's Rocks, Tectonics & Glaciers

• First rocks on Earth emerged 4 billion years ago.
• Basalt constitutes the ocean floor and crust.
• Granite makes up continents.
• Tectonic plates move over the mantle and subduct, returning to molten form.
• Lighter elements and minerals rise during subduction, cool, and form granite.
• A mine near Thunder Bay, Ontario, contains North America's oldest rock, aged 3 billion years.
• Laurentia represents the oldest section of North America.
• The east coasts of North America were formed by the collision of island "conveyor belts".
• Land is not permanent due to constant tectonic plate motion and erosion.
• The Pacific coast's current appearance results from colliding plates (convergent plate boundary).

Glaciers

• Glaciers form through long-term ice accumulation.
• Snowfall compresses underlying layers into solid ice.
• The deepest ice layers are the oldest, with the newest on top.
• Deeper snow/ice is denser.
• Glaciers erode due to rock fragments acting as sandpaper.
• Albedo effect refers to a surface's ability to reflect sunlight and heat.
• Snow has a high albedo, while black asphalt has a low albedo.

Plate Boundaries

• Convergent plate boundary: Plates meet, one subducts, or they collide upward.
• Divergent plate boundary: Plates separate, creating a mid-ocean rift.
• Transform plate boundary: Plates move parallel to each other.

Rock Types

• Igneous rocks form from cooled magma or lava; cooling location affects characteristics.
• Sedimentary rocks are weathered and eroded materials compacted over time.
• Metamorphic rocks are altered by pressure and high temperatures, causing chemical changes.

Geological Processes

• Weathering: Breaking rocks via water, wind, chemicals, and living things.
• Erosion: Moving broken rock pieces.
• Deposition: Settling of broken rock pieces in a new area.
• Glacier: Layers of compacted snow accumulated over time.
• Glaciation: Ice advancing and covering large areas.

Geological Eras

• Cenozoic:
  • Most recent era.
  • Rocky Mountains finished forming.
  • Continents take present shape.
  • Ice sheets cover much of North America.
  • Modern life forms evolve; humans develop.
  • Age of mammals.
• Mesozoic:
  • Shallow seas in North America's interior.
  • Innuitian Mountains formed.
  • Rocky Mountains began forming.
  • First birds and mammals appear.
  • First flowering plants.
  • Age of reptiles (dinosaurs).
• Paleozoic:
  • Large parts of North America covered in shallow seas.
  • Appalachian Mountains formed.
  • First insects.
  • Age of amphibians and fish.
• Precambrian:
  • First and longest era.
  • Precambrian shields formed.
  • First single and multi-celled organisms.