Geology: Continental Drift and Plate Tectonics

Study Notes

Continental Drift

The theory of continental drift states that the continents are constantly shifting their positions.
Pangea was a supercontinent millions of years ago.
Evidence of continental drift is found in:
- The continents fitting together like a jigsaw puzzle.
- Identical plants and fossils being found on distant continents.
- Comparable mountain ranges with similar ages and structures.
- Evidence of ice sheets in regions with generally warm climates.

Plate Tectonics

The theory of plate tectonics differs from continental drift by explaining the movement of the Earth’s outer shell, which consists of tectonic plates.
The Earth’s crust was cooler than the mantle, which led to the formation of plates — the crust cracked as it cooled.
Convection cells drive the movement of these plates:
- Molten rock in the mantle is heated by the core, becoming less dense and rising towards the surface.
- Upon reaching the lithosphere, the molten rock cools, becomes denser, and sinks back into the mantle.
- This continuous process leads to the movement of the plates.

Plate Movements

Divergent plates move apart, creating volcanoes, earthquakes, and valleys.
Convergent plates move towards each other, resulting in trenches, earthquakes, and volcanoes.
Transform plates slide past each other, causing earthquakes.
Divergent plates create new Earth’s surface by allowing magma to rise and cool.
Convergent plates recycle old Earth’s surface by causing mountains to form through faulting and breakage.

Earthquakes

Earthquakes are classified into two main types: transform and convergent.
Transform earthquakes occur when locked tectonic plates release built-up energy.
Convergent earthquakes happen when the edge of a plate gets caught, causing pressure to build up as another plate is recycled into the mantle.
The magnitude of earthquakes is measured to indicate their intensity.
The Ring of Fire is a zone around the Pacific Ocean with a high concentration of volcanoes and earthquakes.

Glaciers

Glaciers reshape the Earth’s surface through erosion and deposition as they move.
Landform examples of glacial erosion:
- U-shaped valleys
- Striations
- Kettle holes
- Lakes
Landform examples of glacial deposition:
- Moraines
- Eskers
- Drumlins
- Erratics
Glaciers regulate global temperatures by influencing the ocean’s conveyor belt.
Benefits of glaciers include:
- Temperature regulation
- Hydropower and energy resources
- Increased agricultural and industrial opportunities
- Fresh water source
Melting of all glaciers could lead to:
- Release of viruses and bacteria
- Widespread flooding

Landform Regions

Canada has diverse landform regions, each with unique characteristics:
- Canadian Shield:
  - Rocky, with limited soil and vegetation.
  - Not high enough to be classified as a highland.
  - Rich in mineral resources.
- Highland Regions:
  - Characterized by high elevations, including mountains and plateaus.
  - Examples: Western Cordillera, Appalachian Mountains, Innuitian Mountains
- Lowland Regions:
  - Relatively low elevations, with rolling hills.
  - Examples: Great Lakes-St. Lawrence Lowlands, Arctic Lowlands, Interior Plains.
- Interior Plains:
  - Known as Canada’s breadbasket due to its agricultural potential.
- Great Lakes & St. Lawrence Lowlands:
  - The smallest region in Canada.
  - A hub for urban and industrial activities.
- Hudson Bay & Arctic Lowlands:
  - Characterized by swampy and icy plains.
- Appalachian Mountains:
  - The oldest highland region.
- Innuitian Mountains:
  - Known as icy mountains.
- Western Cordillera:
  - The youngest highland region.

Soil

Soil in areas with high precipitation experiences leaching, where nutrients are washed away by rainwater.
Soil in areas with less precipitation undergoes calcification, where water evaporates from the topsoil, leaving concentrated minerals and salts.
Humus is the top layer of soil and vital for plant growth.
Loam is ideal for plant growth as it has a balanced composition of humus, sand, silt, and clay.
Permafrost, a permanently frozen layer of soil, is found in the tundra and hinders plant growth.

Description

Explore the theories of continental drift and plate tectonics in this quiz. Learn about the movement of continents, the evidence supporting these theories, and the mechanisms driving tectonic activity. Assess your understanding of Earth's geological processes and historical formations.