FLUVIAL PROCESSES Flashcards
Weathering
Breakdown + decay of rock by natural processes without any moving force (no movement)
Erosion
Wear away and moving (transport) of material by a moving force
Mass movement
Movement of material (weathered) downslope due to gravity
Deposition
Disposal of material carried by a moving force (e.g. river)
Load
All material being transported by the river
Bed load
All material transported on the river bed
4 types of erosion
- hydraulic action
- Abrasion
- Attrition
- Solution
Hydraulic action
Water enter cracks in rocks in the river bank and bed, breaking it apart and carrying it away
Abrasion
Scraping of rocks against the river bed
Attrition
Particles in the river collide with each other, making them rounded and smaller
Solution
Soluble minerals in rocks are dissolved and carried away by the river
4 methods of transport
- Traction
- Saltation
- Suspension
- Solution
Traction
Large rocks rolling along the river bed
Saltation
Smaller rocks bouncing along the river bed
Suspension
Light material carried along by river flow, not heavy enough to sink
Physical/mechanical weathering
- Thermal expansion: rock expand by sun and contracts at night. Breaks rock over time
- Freeze-thaw weathering: Water in cracks freezes and expands. Breaks/fractures rock
Chemical weathering
Breakdown of rocks due to acid rain
Biological weathering
roots of plant enter cracks of rocks and gradually split the rock
2 types of mass movement
- Slumping: bottom of valley is cut away by river. Slope becomes unstable and weathered material slumps down
- Soil creep: gradual movement of weathered material down slope due to gravity, collects at bottom of valley
weathered material
Deposition
When river has less energy, lower discharge. Happens near sea/lake, and inner bends of meanders
Vertical and lateral erosion
Vertical erosion : deepening of river bed
- Lateral erosion: widening of a river channel
