River Landscapes in the UK Flashcards
Erosion: Hydraulic Action
River bank and bed; forces air to become trapped in cracks in rocks, causing rock to break apart
Erosion: Abrasion
River bed and bank, pebbles grind, sand-paper effect
Erosion: Attrition
Rocks hit against each other, breaking apart to become smaller pebbles
Erosion: Solution
Chemical erosion of rocks (eg, limestone and chalk), dissolving them
Transportation: Traction
Large, heavy boulders rolled along river bed, load is larger, (upper course)
Transportation: Saltation
Pebbles bounced along river, (middle course)
Transportation: Suspension
Light sediment is suspended, (lower course)
Transportation: Solution
Dissolved chemicals, soluble rocks (eg, chalk, limestone), (middle, lower course)
Deposition
River loses energy, drops carried material
Factors Leading to Deposition
- Shallow water
- Lower course, current speed changes (estuary)
- Inside bend of a meander (slower current)
Drainage Basin: Area around river drained by river and its tributaries
Water shed — area of high land forming the edge of river basin;
Source — beginning of river;
Mouth — where river meets the sea;
Confluence — point at which two rivers meet;
Tributary — small river or stream that joins larger river;
Channel — where river flows
River Profiles: Long Profile
Line representing the river from its source to its mouth, shows how river changes over its course
Upper Course
Steep gradient; narrow; vertical erosion; hydraulic action; steep valley sides; abrasion and traction; waterfalls, interlocking spurs, gorges, v-shaped valley
Middle Course
Decreasing gradient; wider deeper; energy increases; lateral and vertical erosion; saltation, attrition; higher discharge; meanders, oxbow lakes
Lower Course
Gentle gradient; wider, deeper channel; high energy starts to slow down; lateral, vertical erosion; suspension, solution; levees, deltas, estuaries, floods
Erosional Landforms: Waterfalls and Gorges
Hard rock —> gorge Soft rock Plunge pool 1. Soft rock erodes quicker than hard rock —> undercut hard rock —> overhang 2. Overhang collapses, no support 3. Abrasion and hydraulic action erode bottom —> plunge pool 4. Process repeats 5. Waterfall retreats upstream 6. Steep-sided valley left is the gorge