COR008-2ND_QUARTER

Module 15: Geologic Process on the Surface of the Earth

Weathering

  • Definition: Breaking down or dissolving rocks and minerals on Earth's surface.

Types of Weathering

Physical/Mechanical Weathering

  • Breakdown through mechanical processes (heat, water, ice).

Chemical Weathering

  • Chemical reactions with water, gases, and biological factors.

Mechanical Disintegration Processes

  • Frost Wedging: Water enters cracks and freezes, expanding and breaking rock.

  • Salt Crystal Growth: Evaporation leaves salt crystals that exert pressure.

  • Abrasion: Erosion caused by collisions of particles.

  • Biological Activity: Roots grow into cracks, widening them.

Factors Affecting Weathering

  1. Climate: Cold & dry areas = slow chemical weathering, while hot & wet areas = active chemical weathering.

  2. Rock Type: Different minerals have varying susceptibility to weathering.

  3. Rock Structure: Presence of joints or faults influences weathering rates.

  4. Topography: Steep slopes weather faster due to gravity.

  5. Time: Exposure length affects the degree of weathering.

Erosion

  • Definition: Transport of weathered materials.

  • Agents of Erosion: Water, wind, ice, and gravity.

Types of Erosion

Glacial Erosion

  • Ice plucking creates U-shaped valleys.

Fluvial (Water) Erosion

  • Rain Splash, Sheet Erosion, Rill Erosion: Waves of water cause soil and rock movement.

Aeolian (Wind) Erosion

  • Deflation & Abrasion: Movement and sculpting by wind.

Gravity-related Erosion

  • Movement of materials down slopes.

Deposition

  • Process of adding sediments to new locations; leads to soil formation.

  • Rivers depositing soil at mouths create new landforms.

Module 16: The Continental Drift Theory

Historical Context

  • Observed in 1596 by Flemish Cartographer Abraham Ortelius, noting the fit of continents.

  • Alfred Wegener (1912): Proposed Pangea, rejected due to lack of movement explanation.

Evidence Supporting Continental Drift

  1. Fossil Distribution: Similar fossils across continents.

  2. Rock Layer Continuity: Mountain ranges match across oceans.

  3. Glacial Deposits: Found in now warm climates.

  4. Climate Evidence: Past climates indicated by geological findings.

Plate Tectonics

Theory Development

  • Introduced in the 1940s; proposes thermal convection in the mantle affects continental movement.

Plate Boundaries

  1. Divergent: Plates pull apart, forming new crust (e.g., Mid-Atlantic Ridge).

  2. Convergent: Plates collide; one is subducted, leading to mountain formations.

  3. Transform: Plates slide past, causing earthquakes (e.g., San Andreas Fault).

Geologic Folding and Faulting

  • Folding: Compression causes rock layers to bend.

  • Faulting: Fracturing creates fault lines due to displacement forces.

Seafloor Spreading

  • Theory: New oceanic crust forms as magma rises at divergent boundaries.

Geologic Time Scale

Divisions

  • Eons: Longest periods, subdivided based on fossil presence.

  • Eras: Major shifts in fossil records.

  • Periods/Epochs: Shorter divisions reflecting significant changes.

Geological Hazards

Types

  1. Earthquakes: Ground shaking from rock slippage; hazards include ground shaking, surface faulting, and tsunamis.

  2. Volcanic Eruptions: Release of magma causing hazards like tephra, pyroclastic flows, and toxic gases.

  3. Landslides and Tsunamis: Moving debris due to instability and seismic activity.

  4. Hydrometeorological Hazards: Include storms leading to damage from flooding, cyclones, and tornadoes.

Climate and Weather

Definitions

  • Meteorology: Study of the atmosphere and weather prediction.

  • Weather: Short-term atmospheric conditions.

  • Climate: Long-term average of weather.

Factors Affecting Climate

  1. Latitude, Altitude, Topography, Bodies of Water, Prevailing Winds.

Climate Change

  • Definition: Long-term changes in temperature and weather patterns, primarily driven by human activity.

  • Mitigation Strategies: Include reducing gas emissions, improving energy efficiency, shifting to renewable sources, preventing deforestation, and promoting sustainable practices.