Theme 1: Landscapes and Physical Processes Flashcards
A*
What 4 features explain what a landscape is like?
Geology
Land use
Vegetation
People
What is river discharge?
The quantity of water passing through a river channel at a given point at a given period of time.
What are the 4 stages of V-shaped valleys being created?
- vertical erosion - low discharge in upper course = only erode downwards
- weathering - valley sides slowly broken down
- loose material - weathered material rolls into river, steepening valley sides
- Now a typical v-shaped valley, a typical trait created by upland rivers
What are interlocking spurs?
Areas of dense and resistant rock, river must weave around.
What does vertical erosion do?
River erodes its river bed.
What does lateral erosion do?
river erodes it’s bank.
What is hydraulic action?
The sheer force of water against the rock trapping air in cracks, cracks get bigger, material washed away.
What is attrition?
Stones carried by the river collide together, broken down, smoother + smaller.
What is abrasion?
Small stones grate against the rock face like sandpaper
What is solution? (erosion)
Slightly acidic water dissolved chalk + limestone over time.
What are the processes of erosion?
hydraulic action
attrition
abrasion
solution
What are the river transport processes?
Traction
saltation
suspension
solution
What is traction?
Large stones roll along river bed.
What is saltation?
Small pebbles bounced along river bed in a ‘leap-frog’ fashion.
What is solution? (transportation)
Some materials dissolved in water. (same as erosion)
How do waterfalls retreat? (3 stages)
- Soft rock eroded quicker by erosion.
- Plunge pool + undercutting created.
- Hard rock collapses from no support, falls into plunge pool.
(repeats and retreats towards source over time)
What is a gorge?
A steep-sided narrow valley formed by retreating waterfall.
What’s a meander and what does erosion do to them?
Turns/bends in a river.
Due to erosion, meanders migrate across the valley floor.
What’s the inner bend?
The inside bend, normally shallower with a slower flow.
What’s the outer bend?
The outside bend, normally deeper with faster flow.
What’s the undercutting? (meanders)
Erosion cuts into the outside bend. Generally happens there as more erosion happens there.
What’s a river cliff?
On outer bend, caused by undercutting of the river bank.
What is the slip off slope?
A gentle gradient with large areas of deposition. On inside bend, more deposition there.
What are levees?
When there is an increase in the volume of water flowing in the river, there is an increase in alluvium. When a river floods, natural walls are created on the sides of the river.
What are floodplains?
An area of flat land alongside a river.
What are the 3 stages of levees?
- During a flood, water flows over the banks and deposits silts.
- In between floods, a slow moving river deposits silt in river.
- Every flood, levees build up. In between floods, the river bed is built up too.
What is an ox bow lake?
A lake formed by a river cutting off a meander and finding a straighter and shorter route.
What is alluvium?
Debris, gravel, sand, and smaller materials deposited by flowing water.
What is the process of freeze-thaw (physical) weathering?
- Water enters crack in rock
- Water freezes (at night) and expands, widening gap
- Ice melts (in day), water fills widened gap
- Process repeats until rock splits.
What is biological weathering?
The roots of plants/burrowing animals dig into the soil/rock around the cliffs, which weakens it and it starts to break away.
What is chemical weathering? (carbonation)
Rain and salt water is sometimes acidic which can react with the carbonates in the limestone rocks, creaking cracks.
What is mass movement?
The downhill movement of cliff material under the influence of gravity. (landslide)
What is rockfall?
Weathering processes weaken the cliff, fragments fall away.
What is soil creep?
Slow moving landslide.