Water and Wind related landforms - Arid landscapes Flashcards
Alluvial Fans
Formation: Streams emerging from mountains deposit sediment due to reduced velocity
Location: base of steep slopes on piedmonts (flat terrain)
Bajada
Formation: Coalescence of multiple alluvial fans from adjacent streams
Location: base of sleep slopes, piedmonts
- Continuous slope of sediment deposition
Box canyon/Wadis
Formation: intermittent streams eroding steep-sided channels in desert valleys
- Dry most of the year, flow during flashfloods
- Can transport sediment loads
Playa Lakes
Formation: Temporary water bodies im desert basins
- Evaporation leaves behind salt and mineral crust
Ephemeral Streams
Formation: seasonal rivers flowing during heavy rain
- Collect in local depressions where they wait for a bit and then evaporate, leaving behind playas
e.g. Nile tributes
Reticulate Drainage Patterns
Formation: Interconnected networks of small, temporary channels
Location: Flat arid plains with minimal gradient
- Indicates infrequent and irregular water flow
Natural Bridges
Formation: Erosion by flowing water through rock walls leaving a bridge
- Result of long-term weathering in canyons or cliffs
Anabranches
Formation: Branches of a river diverge and rejoin the main channel
- Found in flat plains, persist over long distances
e.g. Darling River, Australia
Exotic Streams
Rivers originating in wetter areas flow through arid zones
Maintain flow despite arid conditions
e.g. Nile, Colorado rivers
Rain Splash
Raindrops dislodge sand particles on exposed surfaces
Initiates erosion by moving sand downslope
Runoff
Water flows over land after heavy rain, carrying sediment
High in arid areas due to sparse vegetation and impermeable surfaces
Barchan Dunes
Shape: Crescent shaped with horns pointing downwind
Formation: Occur in areas with a consistent wind direction and limited sand supply
Characteristics: Move relatively quickly across desert floors due to limited sand anchorage
Parabolic Dunes
Shape: U-shaped with tips pointing upwind
Formation: Anchored by vegetation, typically found near coasts or areas with some moisture
Characteristics: Form in areas where sand supply is abundant but wind and vegetation coexist
Longitudinal/Seif Dunes
Shape: Long, narrow ridges parallel to wind direction
Formation: Created by bidirectional winds converging at an angle
Characteristics: Can stretch for ages
Lunettes
Formation: Crescent shaped dunes formed by wind-blown sediments around playa lakes
Align perpendicular to prevailing winds; fine silt and clay composition
