Geology and Glaciation Summary

What is Geology?

  • Study of the Earth's rocks.
  • Important for understanding:
  • Landforms and their changes over time.
  • Natural disasters (earthquakes, tsunamis, volcanoes).
  • Valuable minerals (gold, diamonds).
  • Fossil fuels (oil, natural gas, coal).
  • Earth's history and ancient lifeforms.

Types of Rocks

  1. Igneous: Formed from solidified magma (e.g., granite, basalt).
  2. Sedimentary: Formed from eroded sediment deposited and compressed (e.g., limestone).
  3. Metamorphic: Formed from other rocks under heat and pressure (e.g., marble).

The Rock Cycle

  • Magma: Melts to form igneous rocks.
  • Weathering & Erosion: Break down rocks to sediments.
  • Heat & Pressure: Change rocks into metamorphic forms.

Layers of the Earth

  • Crust: Solid layer we live on; floats on mantle.
  • Oceanic crust: Thinner and denser (5-10 km thick).
  • Continental crust: Thicker and less dense (30-50 km thick).

Continental Drift

  • Alfred Wegener's theory (1912): continents were once joined as Pangaea.
  • Evidence:
  • Jigsaw fit (e.g., South America and Africa).
  • Similar fossils and rock types across continents.

Tectonic Plates

  • Earth's crust is divided into tectonic plates (float on the mantle).
  • Move due to convection currents in the mantle.

Types of Plate Boundaries

  1. Divergent: Plates move away (sea-floor spreading).
  2. Convergent: Plates collide (mountain formation or subduction).
  3. Transform: Plates slide past each other (causing earthquakes).

Glaciation

  • Process of glaciers growing, shrinking, and moving.
  • Glaciers shape land by eroding and depositing materials.
  • Alpine Glaciers: Affect mountain areas.
  • Continental Glaciers: Cover continents, scrape land.

Effects of Glaciation

  • Glacial features like valleys, lakes, and moraines.
  • E.g. Don Valley, Oak Ridges Moraine, formed by glacial activity.

Canadian Geologic Eras

  1. Precambrian: Earth's earliest rocks; oldest rocks in Canadian Shield.
  2. Paleozoic: Ancient seas; formation of fossil fuels.
  3. Mesozoic: Dinosaurs and mountain chain formations.
  4. Cenozoic: Ice Age effects; evolution of modern species.