River landforms and processes: weathering, mass movement, erosion, transport and deposition; the long profile and changing valley cross-profile; upper-course landforms (V-shaped valleys, waterfalls, gorges) and lower-course landforms (meanders, ox-bow lakes, floodplains, levees); and a UK river landscape.

What this dot point is asking

This is part of Eduqas GCSE Geography A (C111) Theme 1, Landscapes and Physical Processes, assessed in Component 1. Eduqas expects you to know the geomorphic processes (weathering, mass movement, erosion, transport, deposition), how they change along a river's long profile and cross-profile, how they form upper-course landforms (V-shaped valleys, interlocking spurs, waterfalls, gorges) and lower-course landforms (meanders, ox-bow lakes, floodplains, levees), and to study one UK river landscape with named landforms.

Weathering, mass movement and river processes

Before the river acts, weathering and mass movement prepare and deliver material to the channel.

The river itself does three jobs. Erosion uses hydraulic action (the force of water forcing apart cracks), abrasion (the load scraping the bed and banks), attrition (load particles knocking together and rounding off) and solution (acids dissolving rock). Transport moves the load by traction (rolling), saltation (bouncing), suspension (carried in the flow) and solution (dissolved). Deposition happens when the river loses energy (lower gradient, less discharge, the inside of a bend, or the mouth).

The long profile and cross-profile

A river's long profile is the gradient from source to mouth: steep in the upper course, gentle in the lower course, forming a concave curve. The cross-profile is the shape of the valley across the channel: a narrow, steep V in the upper course; a wide, flat-floored valley in the lower course. Because energy is used differently along the course, vertical erosion (downwards) dominates upstream and lateral erosion (sideways) and deposition dominate downstream.

Upper-course landforms

In the steep upper course, vertical erosion cuts a deep valley.

Lower-course landforms

In the gentle lower course, lateral erosion and deposition shape the land.

A meander is a bend in the river. On the outside of the bend the water is deeper and faster, so erosion cuts a steep river cliff; on the inside the water is shallower and slower, so deposition builds a gentle slip-off slope. Continued erosion narrows the neck of a meander loop until, often during a flood, the river cuts across the neck; deposition then seals off the old loop to leave an ox-bow lake.

A floodplain is the wide, flat valley floor either side of the channel. When the river floods, it spreads out, slows and deposits fine silt (alluvium) across the floor; repeated floods, plus meander migration, build and widen the fertile floodplain. Levees are raised banks of coarser sediment deposited along the channel edges during floods, as the river drops its heaviest load first when it overtops its banks.

A UK river landscape

Eduqas requires one UK river studied in detail. A common choice is the River Tees in north-east England: it rises in the high Pennines, where its upper course has a steep V-shaped valley, interlocking spurs and the High Force waterfall over the hard Whin Sill; its middle and lower course shows large meanders near Yarm and a broad floodplain before reaching the sea at Middlesbrough. Learn how the processes change from source to mouth and which named landforms appear where.

Try this

Q1. Explain how a V-shaped valley forms. [4 marks]

• Cue. Vertical erosion cuts down; weathering and mass movement attack the sides; material is washed into the channel; interlocking spurs remain.

Q2. Explain how levees are formed. [4 marks]

• Cue. During a flood the river overtops its banks, loses energy and deposits its coarsest load first, building raised banks along the channel edge over repeated floods.