Which primary erosional process initially shapes the V-shaped valley that develops into an alluvial fan system?

💡 Explanation

When steep slopes experience persistent rainfall, hydraulic action from concentrated water flow erodes downwards because the water's force dislodges and transports material, initiating the valley. Therefore, hydraulic action is the primary process, rather than glacial abrasion, chemical dissolution, or sediment attrition which require other specific conditions to predominate.

• Which erosional process primarily initiates stream meander formation within an alluvial floodplain environment?
• Near a gradually subsiding river delta which outcome occurs due to the reduced sediment supply?
• Which phenomenon exacerbates lahar formation following a volcanic eruption event?
• Which depositional pattern develops when a mountain stream abruptly enters a broad, dry valley?
• Which slope deformation results when freeze-thaw cycles saturate soil?
• Which risk increases when an earthquake occurs in a region with unconsolidated, water-saturated sediment?