Which process limits sediment buildup on steep upper reaches of alluvial fans?

💡 Explanation

When flow is unconfined on alluvial fans, shallow sheet wash erosion occurs because rainfall detaches and transports fine sediment, limiting buildup on steeper slopes. Therefore, sheet wash limits deposition rather than vegetation, weathering, or wind which typically occur over longer timescales or different environmental conditions.

• Which hazard most directly results when large concentrations of tephra are remobilized downslope after initial deposition?
• Which outcome occurs when increased tephra plume static?
• Which outcome occurs when rapid isostatic rebound exposes coastal alluvial deposits after deglaciation?
• Which substance accumulates when weathering decreases infiltration rates?
• Which geological feature’s formation follows the cutoff of a river meander loop alongside a floodplain lake?
• Which risk escalates when increased Arctic air temperatures degrade permafrost layers under a sloped landscape?