Lecture 2 - Weathering, Karst, Rivers, Oceans, Wind (with audio lecture) (1)

Lecture Overview

• Title: Weathering, Karst Landscapes, and Mass Movement

• Topics Covered:

  • River Systems

  • Oceans, Coastal Systems, and Wind Processes

Part 1: Weathering, Karst Landscapes, and Mass Movement

Geomorphology

• Definition: Study of the origin, development, and distribution of landforms.

• Processes:

  • Endogenic: Internal Earth processes (faulting, volcanic activity).

  • Exogenic: External Earth processes (weathering, erosion, mass movement).

• Key Topics:

  • Weathering and mass movement

  • River systems and landforms

  • Wave and wind landscapes

  • Glacial landforms

Landmass Denudation

• Definition: Processes that wear away or rearrange landforms:

  • Weathering

  • Mass movement

  • Erosion

  • Transportation

  • Deposition

• Driving Forces: Moving water, air, waves, ice; influenced by gravity.

• Resistance: Earth’s material resistance to these processes.

Weathering vs. Erosion

• Weathering: Breakdown of rocks into mineral fragments;

  • Types:

    • Mechanical Weathering

    • Chemical Weathering

  • Factors influencing weathering:

    • Rock composition

    • Climate

    • Slope orientation

    • Water table position

    • Vegetation cover

• Erosion: Transport of weathered materials to new locations.

Physical Weathering Processes

• Frost Weathering: Water freezing in cracks expands.

• Salt-Crystal Weathering: Crystal formation in arid areas.

• Vegetation Weathering: Roots of trees breaking apart rocks.

• Exfoliation: Rock layers peeling off due to exposure.

Chemical Weathering Processes

• Hydration: Water combines with minerals.

• Hydrolysis: Water chemically alters minerals.

• Oxidation: Reaction to air causing rust.

• Dissolution of Carbonates: Forms acids that result in karst topography.

Differential Weathering

• Examples:

  • Delicate Arch, Utah

  • Hoodoos, Alberta

Dynamic Equilibrium Model

• Definition: State where river's water flow neither erodes nor deposits sediment effectively.

• Concept: Balance between erosion resistance of rocks and erosive forces at work.

Karst Topography

• Formation: Dominantly formed by limestone dissolution.

  • Main Component: Calcium carbonate (CaCO3).

  • Origin: Forms in clear, warm, shallow marine waters.

Sinkholes

• Definition: Circular depressions in soil surface.

• Types:

  • Solution Sinkholes: Formed by dissolution of limestone.

  • Collapse Sinkholes: Created by the collapse of underground caverns.

• Karst Valleys: Coalescence of multiple sinkholes.

Caves and Caverns

• Cave: A large underground area.

• Cavern: A notably large cave.

• Stalactites: Mineral formations from cave ceilings.

• Stalagmites: Formations on cave floors.

Karst Topography in Indiana, USA

• Features:

  • Rolling landscapes, sinkholes, karst valleys, and disappearing streams.

Eramosa Karst

• Location: Stoney Creek, Ontario.

• Features: Sixteen distinct karst geological features.

Dolomite

• Definition: A sedimentary rock formed from ancient lime mud alteration.

• Characteristics: Hard and resistant to erosion, found in Niagara Escarpment.

Mass Movements

• Definition: Downhill movement of materials under gravity.

• Conditions: Involves gravity, slope, debris content, moisture, and surface resistance.

• Types:

  • Falls

  • Slides

  • Flows

  • Creep

Classes of Mass Movement

• Examples:

  • Rock Falls: Falling rocks through air.

  • Debris Avalanche: Fast-moving rock and soil due to water/ice.

  • Landslides: Rapid mass movement of dry materials.

  • Mudflows: High moisture content.

  • Soil Creep: Gradual surface soil movement.

Forces on a Slope

• Directional Forces: Affect slope stability, causing erosion.

• Potential Energy: Stored energy influencing mass movement.

Scarification: The Human Impact

• Human Activity: Greater geomorphic influence than natural processes (mainly mining).

Part 2: River Systems

Fluvial Geomorphology

• Study: Interactions of streams and landscapes.

Drainage Basin

• Definition: Area providing water to a stream (watershed).

The Great Lakes

• Significance: Largest fresh water body, crucial for ecosystems.

Terminology in River Systems

• Headwater: Source region of a river.

• Tributary: Stream flowing into a larger waterbody.

• Confluence: Meeting point of two rivers.

• Mouth: River ending in a larger water body.

Continental Divides and Drainage Basins

• Major drainage basins leading to various oceans.

Drainage Patterns

• Common Patterns:

  • Dendritic (tree-like)

Fluvial Processes

• Mix of water and solids affecting erosion, transport, deposition:

  • Erosion: Material removal.

  • Transport: Movement of material.

  • Deposition: Dropping sediment.

V-Shaped Channels

• Characteristics: Formed by erosion, steep slopes, and high water volume.

The Grand Canyon

• Anatomy: Deep valley created by the Colorado River over millions of years.

Meandering Streams

• Features: Curvy channel, low gradient, sediment interaction.

Humber River Example

• Location: Summerlea Park, Ontario.

Depositional Landforms

• Types:

  • Alluvium

  • Alluvial fan

  • Delta

  • Estuary

Alluvium Definition

• Unconsolidated materials deposited by water.

Alluvial Fan

• Deposits in arid climates due to sediment dropping from flowing water.

Delta Formation

• Forms at river mouths where sediment accumulates.

Estuaries:**

• Transition between rivers and maritime environments; crucial for ecosystems.

Importance of Estuaries

• Role: Provide nurseries for marine species; highly productive ecosystems.

Ground Water and Aquifers

• Definition: Saturated zone beneath water table; declining water levels of aquifers.

Part 3: Oceans, Coastal Systems, and Wind Processes

World Water Distribution

• Overview: 98% salt water, 2% freshwater (most in ice).

The Five Oceans

• List: Atlantic, Pacific, Indian, Antarctic, Arctic.

• Salinity: Concentration of dissolved salts in seawater.

Physical Structure of Oceans

• Zones:

  • Mixing Zone

  • Thermocline

  • Deep Cold Zone

Ocean Relief

• Features of ocean floor:

  • Continental shelf

  • Continental slope

  • Mid-ocean ridges

Mariana Trench

• Description: Deepest ocean trench; extreme conditions.

Littoral Zone

• Coastal area affected by storm waves.

Intertidal Zones

• Area between high and low tide levels.

Ocean Habitats

• Diverse ecosystems influenced by depth and proximity to shorelines.

Salt Marshes

• Coastal ecosystems flooded by tides; crucial for biodiversity.

Mangrove Forests

• Ecosystem along intertidal zones; stabilizes coastlines.

Coral Reefs

• Biodiverse underwater structures created by coral; vital marine habitats.

Coral Bleaching

• Consequence of heat stress leading to coral death.

Carbon Dioxide Absorption

• Oceans as carbon sinks; concern over ocean acidification.

Ocean Gyres

• Circular currents influenced by wind and Earth's rotation.

Climate Regulation by Ocean Currents

• Currents regulate climate by moving warm and cold water around the planet.

Thermohaline Circulation

• Deep ocean currents responsible for distributing heat globally.

El Nino

• Weather phenomenon causing significant climate impacts globally.

La Nina

• Opposite effect of El Nino, typically cooler ocean temperatures.

Effects on North America

• How El Nino and La Nina influence weather patterns.

Eolian Processes

• Erosion: Wind-caused ground surface erosion.

  • Deflation: Removal of particles by wind.

  • Abrasion: Rock surface shaping by wind.

Transporting Sand

• Mechanisms of sand movement by wind: saltation, suspension, creep.

Wind-Driven Deposition

• Formation of sand dunes in various environments.

Sandbanks Provincial Park

• Location of a significant sand spit and geological features.