Concordant & Discordant Coastlines Geography - Revision Notes

Introduction

• The study focuses on the different types of coastlines and the processes affecting them.
• The main processes discussed include weathering, erosion, transportation, and deposition.

Weathering & Mass Movement at the Coast

Definition of Weathering

• Weathering: Breakdown of rock in-situ, different from erosion which involves movement.
• Sub-aerial weathering: Includes processes not linked to sea action, like freeze-thaw and chemical weathering.

Types of Weathering

Mechanical Weathering

• Mechanical weathering: Physical breakdown of rocks.
• Example: Freeze-thaw weathering.

Chemical Weathering

• Involves chemical processes that break down rocks.
• Rainwater absorbs CO2, becomes acidic, reacting with minerals.
• Limestone weathers faster than granite.

Biological Weathering

• Caused by living organisms like trees and plants.
• Roots grow in cracks, breaking rocks apart.

Mass Movement

• Downhill movement of material due to gravity.
• Influenced by factors like slope angle, vegetation, water, rock type, human activity, and climate.

Types of Mass Movement

Landslide

• Material moves as a mass until it hits the bottom.

Fall

• Rapid movement on steep slopes.
• Triggered by weathering, rain, earthquakes, hot weather, and wave action.

Slump

• Common in weaker rocks (e.g., clay).
• Saturated slopes move down in one piece, forming curved surfaces.

Erosion, Transportation & Deposition at the Coast

Erosion

• Primarily caused by destructive waves.
• Types: Hydraulic action, attrition, abrasion, solution/corrosion.

Transportation

• Material can come from cliffs, longshore drift, offshore, or rivers.
• Types of movement: Traction, saltation, suspension, solution.

Longshore Drift

• Main process of deposition and transportation.
• Involves zigzag movement along the coast.

Deposition

• Occurs when water velocity decreases, dropping material.
• Forms beaches, saltmarshes, and mudflats in sheltered areas.

Conclusion

• Understanding the various physical processes is crucial for managing and conserving coastal landscapes.
• Different factors influence how coastlines are shaped and changed over time.