Processes of coastal weathering, mass movement, erosion and the characteristics and formation of associated landforms and landscapes — Eduqas A-Level Geography

Coastal weathering, mass movement, and erosion are fundamental processes that shape the dynamic interface between land and sea. Weathering involves the breakdown of rocks in situ through mechanical, chemical, and biological processes, such as freeze-thaw, solution, and root action. Mass movement refers to the downhill transfer of material under gravity, including rockfalls, slides, slumps, and soil creep. Erosion is the removal and transport of material by waves, currents, and tides, with processes like hydraulic action, abrasion, attrition, and solution. These processes work together to create distinctive coastal landforms, including cliffs, wave-cut platforms, caves, arches, stacks, and stumps, as well as depositional features like beaches, spits, and bars.

Understanding these processes and landforms is crucial for A-Level Geography because they illustrate the interaction between geological structure, lithology, and marine processes. The WJEC specification emphasises the role of subaerial processes (weathering and mass movement) alongside marine erosion in shaping coastlines. Students must be able to explain how different rock types (e.g., resistant granite vs. less resistant clay) influence the rate and type of erosion, leading to contrasting landforms such as headlands and bays. This topic also links to broader themes like coastal management, sea-level change, and the impact of human activity, making it a core component of physical geography.

Mastery of this topic requires students to think in terms of systems and cycles. For example, the formation of a wave-cut platform involves a sequence: cliff retreat through erosion, undercutting, collapse, and platform widening. Similarly, the lifecycle of a cave-arch-stack-stump sequence demonstrates the progressive erosion of a headland. By understanding these processes, students can predict how coastlines may evolve over time and evaluate the effectiveness of management strategies. This knowledge is not only exam-relevant but also fosters an appreciation for the ever-changing nature of our planet.

• →Weathering types: mechanical (freeze-thaw, salt crystallisation), chemical (solution, carbonation, hydrolysis), and biological (root action, burrowing).
• →Mass movement processes: rockfall (rapid, on steep cliffs), slides (translational or rotational along a slip plane), slumps (rotational movement on clay cliffs), and soil creep (slow, imperceptible movement).
• →Marine erosion processes: hydraulic action (air compression in cracks), abrasion (sand and shingle scouring), attrition (rocks colliding and wearing down), and solution (dissolution of soluble rocks like limestone).
• →Landform sequences: headland and bay formation (differential erosion), cliff profiles (steep, overhanging, or sloping depending on rock type), wave-cut platforms (gently sloping rock surfaces at cliff base), and cave-arch-stack-stump evolution.
• →Factors influencing process rates: lithology (rock hardness, bedding planes, joints), structure (faults, folds), wave energy (fetch, wind strength), tidal range, and human intervention (groynes, sea walls).

• Sub-aerial processes: weathering (physical, chemical, biotic) and mass movement (landslides, slumps, rock falls).
• Marine erosional processes: hydraulic action, abrasion (corrasion), corrosion, and attrition.
• Characteristics and formation of coastal landforms: cliffs, headlands, bays, cave-arch-stack-stump sequences, wave-cut platforms, geos, and blowholes.
• Application of knowledge to both UK and non-UK coastal landscapes.

• 💡Use clear, annotated diagrams to illustrate the formation of landforms like the cave-arch-stack-stump sequence.
• 💡Ensure you explicitly link the type of erosion (e.g., hydraulic action) to the specific landform feature.
• 💡Use precise geographical terminology for processes (e.g., corrasion instead of just 'erosion').
• 💡Be prepared to apply these processes to non-UK examples as specified in the content.
• 💡Use specific terminology and case studies. For example, when explaining cave-arch-stack formation, name a real location like the Old Man of Hoy (Orkney) or Durdle Door (Dorset) to show applied knowledge.
• 💡Link processes to landforms explicitly. In an answer about cliff retreat, mention how hydraulic action exploits joints, leading to undercutting, then mass movement (e.g., rotational slumping in clay) removes the debris, and the cycle repeats.
• 💡Draw annotated diagrams. For high marks, sketch a sequence showing the stages of headland erosion or a cliff profile with labels for processes like 'abrasion notch' and 'scree slope'. This demonstrates understanding of spatial relationships.

• Confusing the processes of erosion with the processes of weathering.
• Failing to link specific processes to the formation of specific landforms.
• Neglecting the role of lithology and structural geology in influencing erosional landforms.
• Providing generic descriptions of landforms without explaining the geomorphological sequence of development.
• Misconception: Weathering and erosion are the same process. Correction: Weathering breaks rock in place without movement; erosion involves the removal and transport of material by agents like waves or wind.
• Misconception: Cliffs only retreat due to wave erosion at the base. Correction: Subaerial processes like weathering and mass movement are equally important; for example, freeze-thaw weakens the cliff face, leading to rockfalls that then get removed by waves.
• Misconception: A wave-cut platform is formed solely by abrasion. Correction: It is primarily formed by hydraulic action and abrasion undercutting the cliff, followed by collapse and then platform widening through further erosion and weathering.