alluvial fan
River deposit cone
An alluvial fan is a fan-shaped deposit of sediment where a fast-moving stream emerges from steep terrain onto a flatter plain.
As the water spreads and slows, it drops the rocks, gravel, and sand it carried.
The deposits accumulate over time into a broad wedge pattern: The town was built on an alluvial fan at the canyon's mouth.
Devoid of water
- semi-aridModerately low rainfall climate
- desertTo leave behind completely
- mountainTall natural landmass
- canyonDeep river-cut gorge
basin · Death Valley · Mojave · oasis · playa · bajada · pediment · tectonic
Particles settling in liquid
- gravelLoose small rock fragments
- sandFine rock particles
- siltWaterborne earth particles
- clayMoldable earth for ceramics
boulders · cobbles · debris flow · clastic · sorting · stratification · sedimentation · imbrication
Rapid overflow from storms
- ephemeral streamChannel wet only seasonally
- braided streamRiver with intertwined channels
- channel switchingChanging TV stations
- runoffExcess water drainage
drainage basin · watershed · infiltration · permeability · porosity · aquifer · water table · arroyo
arid
Devoid of water
- semi-aridModerately low rainfall climate
- desertTo leave behind completely
- mountainTall natural landmass
canyon · basin · Death Valley · Mojave · oasis · playa · bajada · pediment · tectonic · uplift
sediment
Particles settling in liquid
clay · boulders · cobbles · debris flow · clastic · sorting · stratification · sedimentation · imbrication
flash flood
Rapid overflow from storms
- ephemeral streamChannel wet only seasonally
- braided streamRiver with intertwined channels
- channel switchingChanging TV stations
runoff · drainage basin · watershed · infiltration · permeability · porosity · aquifer · water table · arroyo · wadi
cone-shaped
Tapering to a point
alluvial fanriver delta
Alluvial deposit at mouth
delta · estuary · floodplain · tidal flat
alluvial fancanyon
Deep river-cut gorge
gorge · ravine · gully · valley · slot canyon