Dynamic Surface L3 Flashcards
Where are production and transport rates of sediment/particles highest?
Areas of recent tectonic activity
What is weathering?
The process through which clastic sediment particles are formed and which provides dissolved ions for non-clastic sediments
What is the regolith?
The weathered zone of bedrock
What is physical/mechanical weathering?
The process by which rock is broken down mechanically into smaller fragments
What are the 6 types of physical/mechanical weathering?
Exfoliation/exhumation
Insolation weathering
Hydration weathering
Frost shattering
Salt weathering
Wind erosion
What is exfoliation/exhumation?
The sudden reduction of pressure on a rock resulting in the formation of joints parallel to the top of the rock body between the rock body itself and the material below.
What is insolation weathering?
Repeated variation in the temperature of a rock (day-night cycles) causes continuous expansion and contraction
What is hydration weathering?
The reaction of water with a rock, depending on its mineralogy, can cause swelling/expansion
What is frost shattering?
Water enters cracks in a rock, freezes and expands by about 9% and melts.
What is salt weathering?
Salt spray is blown at a rock, the water then evaporates leaving the salt to crystallise between loose grains of the rock surface, forcing them apart.
What is wind erosion?
Wind picks up fine grains and scours away less resistant rocks and leaves behind more resistant rocks.
Where is chemical and biochemical weathering the most rapid?
Tropic and humid temperate lowlands
Which area of the crust does chemical and biochemical weathering affect and why?
The uppermost 100m of the crust as below this, fractures close and cements reduce permeability.
What 2 factors can accelerate chemical weathering?
Dissolved organic acids from plant debris
Ligands
What is congruent dissolution?
The complete disappearance of a material with no minerals left behind to form any kind of residue