Geography · Year 7 · The Restless Earth: Geomorphology · Autumn Term

Erosion and Deposition

Investigating the agents of erosion (water, wind, ice) and the resulting depositional landforms.

• National Curriculum Attainment Targets
• KS3: Geography - Physical Processes: Geological Processes

About This Topic

Erosion and deposition reshape Earth's landscapes as water, wind, and ice transport and redistribute sediment. Year 7 students examine river processes like hydraulic action and attrition that carve V-shaped valleys, gorges, and meanders, leading to deposition in floodplains and deltas. Glaciers erode through plucking and abrasion to form corries, arêtes, and U-shaped valleys, depositing moraines and drumlins. Wind erodes rock into yardangs and pedestals, depositing sand in barchan dunes and loess sheets. These align with KS3 National Curriculum standards on physical processes and geomorphology in 'The Restless Earth' unit.

Students compare features across agents, analyse human activities such as farming that accelerate erosion or gabion walls that mitigate it, and predict long-term coastal threats to places like Norfolk or Holderness. This fosters skills in spatial analysis, cause-and-effect reasoning, and evidence evaluation using Ordnance Survey maps and photos.

Active learning suits this topic because students model processes with sand, water, and fans to see changes unfold. Direct manipulation clarifies timescales and interactions, while group predictions from models build confidence in applying concepts to real UK landscapes.

Key Questions

1. Compare the erosional and depositional features created by rivers, glaciers, and wind.
2. Explain how human activities can accelerate or mitigate erosion.
3. Predict the long-term impact of coastal erosion on human settlements.

Learning Objectives

• Compare the characteristic landforms created by river, glacial, and wind erosion and deposition.
• Analyze the impact of specific human activities, such as deforestation and construction, on the rate of erosion.
• Evaluate the effectiveness of different coastal defense strategies, like sea walls and groynes, in mitigating erosion.
• Predict the potential consequences of long-term coastal erosion on settlements in vulnerable areas of the UK.

Before You Start

Introduction to Earth's Surface Features

Why: Students need a basic understanding of different landforms before investigating the processes that create them.

The Water Cycle

Why: Understanding the movement of water is fundamental to grasping river erosion and deposition.

Key Vocabulary

Hydraulic action	The force of moving water, especially in rivers and waves, eroding rock by compressing air in cracks and then releasing it.
Abrasion	The process where eroded material, carried by wind, water, or ice, grinds against rock surfaces, wearing them away.
Attrition	The process where rocks and sediment carried by rivers or glaciers collide with each other, becoming smaller and more rounded.
Meander	A bend or curve in a river channel, formed by erosion on the outer bank and deposition on the inner bank.
Moraine	A ridge or mound of rock and soil deposited by a glacier, marking its former extent.
Barchan dune	A crescent-shaped sand dune formed by wind, with its points facing downwind.

Watch Out for These Misconceptions

Common Misconception

Erosion happens only to soft rock or soil.

What to Teach Instead

Rocks erode at different rates based on hardness and jointing, as shown in wave-cut platforms on chalk cliffs. Hands-on tests with varied materials in water flumes help students see abrasion's universal effect, correcting overemphasis on soil via direct comparison.

Common Misconception

Deposition occurs randomly wherever material stops.

What to Teach Instead

Deposition depends on reduced energy, like velocity drop in river mouths forming deltas. Modelling with graded sand in slowing water reveals sorting patterns. Group discussions of simulations refine ideas, linking energy to landform type.

Common Misconception

Human activity has little effect on natural erosion.

What to Teach Instead

Deforestation increases runoff and erosion rates, as in Norfolk's boulder clay cliffs. Role-play scenarios with added 'farming' elements in models shows acceleration. Peer teaching from evidence builds awareness of mitigation strategies.

Active Learning Ideas

Flume Modelling: River Erosion and Deposition

Provide trays with sand layered by colour, pour water at varying speeds to erode channels and deposit sediment downstream. Students measure bank retreat and fan shapes, sketch before-and-after profiles. Discuss velocity's role in transport.

45 min·Small Groups

Fan Simulation: Wind Dune Building

Use hairdryers or desk fans to blow dry sand across trays, observing ripple marks and dune migration. Add obstacles like pebbles to form deflation hollows. Groups record wind direction effects and predict long-term patterns.

35 min·Pairs

Ice Block Demo: Glacier Landforms

Freeze sand-water mix in trays, place weights to simulate flow, melt to reveal striations and moraines. Whole class observes via projector, draws cross-sections. Compare to real photos of Scottish glens.

50 min·Whole Class

Coastal Jenga: Erosion Prediction

Stack blocks as cliffs, 'erode' with water sprays and waves, add defences like sea walls. Pairs time collapse, calculate setback rates, link to Holderness data.

40 min·Pairs

Real-World Connections

• Coastal engineers design and implement coastal defenses, such as the sea walls at Blackpool or the managed retreat strategies in areas of East Anglia, to protect infrastructure and communities from erosion.
• Geologists and environmental consultants assess erosion risks for new development projects, advising on land management practices to prevent soil loss on construction sites or agricultural land.
• National Parks authorities in areas like the Lake District or the Peak District manage footpaths and natural landscapes to minimize erosion caused by visitor numbers and extreme weather events.

Assessment Ideas

Exit Ticket

Provide students with images of three different landforms: a meander, a U-shaped valley, and a sand dune. Ask them to identify the primary agent of erosion responsible for each and write one sentence explaining how it was formed.

Quick Check

Ask students to stand up if they agree with the statement: 'Wind erosion is most effective in areas with high rainfall.' Then, ask a volunteer to explain their reasoning, referencing specific landforms or processes.

Discussion Prompt

Pose the question: 'If you were a local council member responsible for a stretch of coastline experiencing rapid erosion, what are the pros and cons of building a sea wall versus allowing natural processes to continue?' Facilitate a brief class debate.

Frequently Asked Questions

How can active learning help teach erosion and deposition in Year 7?

Active learning engages students through models like sand flumes for rivers or fans for wind, making invisible processes visible. They manipulate variables such as water speed or wind strength, observe landform changes, and predict outcomes, deepening conceptual links. Group work on UK case studies like Holderness fosters discussion, retention, and skills transfer to exams. This beats passive lectures by building spatial intuition over 60-80% better recall.

What erosional and depositional features do rivers create?

Rivers erode via corrosion, hydraulic action, attrition, and solution, forming interlocking spurs, waterfalls, and oxbow lakes. Deposition creates levees, deltas, and braided channels where load exceeds transport capacity. UK examples include the River Severn's meanders. Students map these using OS resources to compare profiles.

How do humans accelerate or mitigate erosion in the UK?

Farming removes vegetation, increasing runoff and soil erosion; urbanisation adds impermeable surfaces speeding river erosion. Mitigation includes terracing, tree planting, and coastal groynes or rock armour. Holderness loses 2m/year; defences like Mappleton walls slow this but cause downdrift issues. Case studies reveal trade-offs.

What long-term impacts does coastal erosion have on settlements?

Coastal erosion threatens homes, roads, and farms through cliff retreat, as at Holderness (1.5km lost since Roman times). Rising sea levels worsen this, displacing communities and raising insurance costs. Predictions use recession rates from LiDAR data; students calculate 50-year risks for sites like Hornsea.