Subaerial Processes Flashcards
Definition of subaerial processes
Literately under the air.
Processes that affect coastal land above the level of the sea and include weathering processes and mass movements.
Three main types of weathering processes
Physical/mechanical
Chemical
Biological
What is weathering?
Breakdown of material in situ.
This means that the rock wears away without any movement.
What is mass movement?
Movement downslope of rocks, sand, clay, glacial till or soil.
Caused by gravity once a slope has become unstable.
This can happen when waves have undercut resistant rocks or when rainwater enters unconsolidated rocks and forces particles apart so that they no longer cohere.
Four main types of mass movement.
Rock falls
Block slides
Rotational slumps
Flows
What is rock fall
Rapid form of mass movement.
Blocks of rock can be dislodged by mechanical weathering or by hydraulic action erosion.
Undercutting of cliffs by the creation of wave-cut notches can lead to large falls.
What is flow?
Common in weak rocks such as clay or unconsolidated sands.
Materials can become saturated, lose their cohesion and flow downslope.
Heavy rainfall combined with high waves and tides can contribute to saturation.
What is rotational slide?
Mass movement can occur along a curved surface.
Huge masses of material can slowly rotate downslope over periods lasting from days to years.
Water plays a dominant part in rotational slides.
Creates a back-scar and terraced cliff profiles.
What is topple?
Geological structure influences topples where rock strata have a very steep seaward dip.
Undercutting by erosion will lead to instability and blocks of material toppling seaward.
