key words Flashcards
What is the meaning of terracettes?
Small terraces from a few centimetres to 0.5m across the face of a slope caused by soil creep or solifluction.
What is the meaning of periglacial?
On the edge of glacial conditions, that is, an area which is covered by snow and ice for some of the year but also experiences a thaw for part of the year. Periglacial areas are commonly affected by intense freeze-thaw activity.
What is the meaning of aspect?
The direction a slope faces; for example, north- and south-facing slopes.
What is the meaning of decomposition?
Chemical weathering of rocks creating new materials.
What is the meaning of disintegration?
Mechanical weathering of rocks resulting in smaller fragments of the same type.
What is the meaning of in situ?
On the spot, that is, without any lateral (sideways) movement.
What is the meaning of exfoliation?
The ‘peeling’ of rocks on their outer edges as a result of repeated thermal expansion and contraction.
What is the meaning of pools?
The deep parts of a river located on the outer bend of a meander.
What is the meaning of riffles?
The ridges - often formed of gravel - found in the straight part of river between two meanders.
What is the meaning of cavitation?
The explosion of air in joints and cracks as a result of air at a very high pressure.
What is the meaning of hydraulic radius?
The cross sectional radius of a river divided by the wetted perimeter.
What is the meaning of the wetted perimeter?
The total length of the bed and base of a river channel in contact with the water in a river.
What is the meaning of the sediment yield?
The amount of material (debris) carried away by water. Often measured in t/km/year.
What is the meaning of entrainment?
Picking up particles from the ground/bed of a river.
What is the meaning of unconsolidated rocks?
Loose, broken material that is often easily eroded.
What is the meaning of consolidated rocks?
Solid rocks or sediments that have been bonded together by a sedimentary cement.
What is a thalweg?
The line of maximum velocity in a river.
What is the meaning of helicoidal flow?
The corkscrew-like motion that occurs in a meander.
What is the meaning of river cliff?
The steep-sided slopes on the outer bend of the meander.
What is the meaning of slip-off slope?
The gentle slope deposited on the inner bend of a meander.
What is the meaning of bankfull stage?
Where a channel variables (depth, width and velocity) of a river are unable to cope with additional water.
What is the meaning of centrifugal?
Outward-moving force.
What is the meaning of Alluvium?
Fine sediments of silt and clay transported in suspension.
What is the meaning of lithology?
The properties of rocks - mineral composition, cracks, joints.
What is the meaning of open systems?
Systems with inputs and outputs.
What is the meaning of watershed or divide?
The ‘line’ dividing two drainage basins.
What is the meaning of biodiversity?
The range of organisms present in a particular ecological community or system. It can be measured by the number of different species or the variation within or between species.
What is the meaning of Flocclation
The process in which clay and silt particles combine when fresh water mixes with the salt water. The heavier particles sink more rapidly.
What is the meaning of sites of specific interest (SSSI)
An area of land of special interest because of its flora, fauna, geological or physiographic characteristics. There are about 6000 SSSIs in Britain. They should be protected from development.
