3. Geomorphology (rivers and coasts) Flashcards
Abrasion
Abrasion - this is when pebbles grind along a rock platform or cliff base much like sandpaper. Over time the rock becomes smooth.
Attrition
When rocks that the river is carrying knock against each other. They break apart to become smaller and more rounded.
Braiding
Braided rivers are a type of river that form a network of many branches within a channel.
Confluence
The point where two rivers (including tributaries) meet
Corrosion
the process of rocks and pebbles carried by the waves wearing away rocks as they are thrown against cliffs.
Drainage Basin
The area of land drained by a river and its tributaries is called
the drainage of river basin
Erosion
The wearing away of material. Erosion can
occur by hydraulic action, abrasion, attrition or
corrosion/solution.
Fault
A line of weakness in rock
Floodplain
the flat area either side of a river which os regularly flooded
Gorge
A deep, steep-sided valley
Hydraulic Action
This is the sheer power of the water as it smashes against the river banks. Air becomes trapped in the cracks of the river bank and bed, and causes the rock to break apart.
Impermeable
not allowing water to pass through
Infiltration
The downward movement of water from the surface into the soil
Interception
This refers to the storage of water on leaf and plant stems
Lower Course
The final stage of the river, usually where it meets the sea.
Middle Course
The section of the river which comes between the upper and lower course.
Mouth
the point where a river enters a sea, ocean, or lake
Oxbow lake
the cut-off remnant of a meander found in the lower course of a river
Porous
A rock with minute air spaces between the minerals.
Permeable Rapids
Permeable rapids are areas in rivers or streams where water can permeate through porous rocks, affecting water flow and hydrological processes.
Plunge pool
a deep pool which is formed by erosion at the base of the waterfall
Reservoir
a lake behind a dam
River cliff
a steep, undercut area on the outside of a river meander
Run off
The sum of all the water flowing over the drainage basin’s surface
Saltation
Saltation involves pebble-sized particles bouncing along the riverbed, which also most commonly happens near the source.
Scree
Loose rocks that fall and gather at the bottom of hills.
Slip-off slope
a gently-sloping area formed on the inside of a river meander.
Solution
When the water dissolves certain types of rocks, eg limestone.
Source
the beginning of a river
Spur
a rocky projection found in the upper section of a river’s cours.
Suspension
the transport of silt in water
Throughflow
The movement of water through the lower soil towards rivers, and groundwater flow.
Traction
the transport of boulders in a rolling motion in water
Tributary
a river joining a larger river
Upper Course
the section of a river near its source, dominated by the processes of erosion
Waterfall
a point on a river where water falls vertically
Watershed
an area of highland separating river basins
Water table
The water table is the underground depth at which the soil and rock are fully saturated with water.
Weathering
The breakdown of material in-situ.
Weathering can be either physical, biological or
chemical.
Transportation
Once material has been eroded it is
carried along by the river. Rivers transport material by traction, saltation, suspension or solution, or
floatation.
Deposition
Where the river loses energy and drops (deposits) its load (the material being carried).
What are the characteristics and processes of the Upper Valley?
Vertical erosion with Hydraulic action, abrasion & attrition dominant processes
Traction and saltation at high flow
Load size is large and angular
V shaped valleys
What are the characteristics and processes of the Middle Course?
Channel is deeper and
wider
Vertical erosion decreasing in importance, more lateral erosion and deposition.
Suspension is the main transportation type
Load becomes smaller and less angular
What are the characteristics and processes of the Lower Course?
Channel is at its widest and deepest, and may be tidal Deposition more important than erosion
Fine material deposited
Large amount of load but the size is very small and very rounded
What is a long profile
LONG profile is the change in gradient with distance. It starts off steep but reduces with distance from source,and has a CONCAVE profile
How are V-shaped Valleys formed
1) river erodes downward.
2) the sides are cut down and attacked by weathering.
3) the loosened material slowly creeps down the slope by gravity or is washed by rainwater.
4) it results in a steep sided valley with the shape of a V.
What are Meanders formed by?
Depositition and Erosion
How Waterfalls are formed?
How are Floodplains formed?
How are Ox-bow lakes formed?
What are Deltas?
rivers empty water & sediment into seas/lakes/oceans
What are Causes of Floods
Climatic conditions e.g. heavy rain, physical
features e.g. steep-sided valley and human factors e.g.
urbanisation.
What are the Effects of Floods?
Buildings destroyed/damaged, people/animals
drown, infrastructure damages, crops ruined, insurance
claims, drinking water contaminated.
What are the 2 ways of Managing floods?
Hard engineering is more expensive and
uses more raw materials to build structures that alter the
existing environment. Soft engineering works with the
natural environment to prevent flooding. Some examples:
