Which process primarily causes the formation of alluvial fans at the base of mountain ranges within arid climates?

💡 Explanation

When a stream exits a confined mountain channel onto a plain, a sudden decrease in gradient occurs, because kinetic energy decreases and the stream loses its capacity to carry sediment, leading to rapid deposition and formation of an alluvial fan. Therefore rapid gradient changes cause alluvial deposition, rather than ice age deposition, localized tectonic activity or wave action.

• Which process prevents thermal overturn in deep meromictic lakes during winter months?
• Which mechanism causes the surface salinity differences along the North Atlantic Gulf Stream?
• Which geophysical effect occurs when a subducting oceanic plate has a rough surface with many seamounts?
• Which process causes sorted sediment deposition on an alluvial fan during sheet flooding events?
• Which risk is amplified when increased stream power transports excessive alluvial sediment load across a subsiding floodplain?
• Which mechanism sustains thermohaline circulation in the Atlantic Ocean when surface water cools significantly during winter?