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Difficulty: MediumOceans, Coastal Processes, and Coastal Landforms

Match each coastal geomorphic process or mechanism on the left with its corresponding characteristic landform on the right.

  • Continuous wave attack and undercutting at the base of a rocky sea cliffWave-cut platform
  • Lateral sediment drift across an estuary mouth forming a linear depositional ridgeSpit
  • Wave refraction behind an offshore island causing sediment to bridge the gap to the mainlandTombolo
  • Eustatic rise in sea level drowning a river valley system along a coastlineRia

Answer

Continuous undercutting at a cliff base matches with Wave-cut platform; lateral sediment drift across an estuary matches with Spit; sediment bridging to an offshore island matches with Tombolo; and sea-level submergence of a river valley matches with Ria.
Each process correctly generates its characteristic landform: cliff base erosion produces a wave-cut platform, longshore drift creates a spit across sheltered water, wave energy dissipation behind an island forms a tombolo, and coastal submergence of river valleys results in a ria.

Step-by-Step Solution

1
Analyze cliff erosion processes.
Marine erosion at the cliff base forms a notch which collapses repeatedly, leaving a flat wave-cut platform exposed at low tide.
Hydraulic action and abrasion concentrate mechanical wave force at high-water level.
2
Analyze coastal sediment transport along estuaries.
Oblique swash and direct backwash move material along the coast until open water causes deposition, building a spit.
Reductions in current velocity where coastlines change direction force waves to drop carried sediment.
3
Evaluate wave interaction behind offshore islands.
Wave refraction creates a low-energy zone behind the island where deposition forms a connecting ridge called a tombolo.
Converging wave crests lose velocity in sheltered water behind coastal obstacles.
4
Examine the effect of relative sea-level rise on coastal river valleys.
Submergence of river valleys produces deep, branching estuaries called rias.
Post-glacial eustatic sea-level rise floods low-lying dendritic river drainage patterns.

Key Concept

Coastal erosional, depositional, and submergent processes and landforms
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Topics

Oceans, Coastal Processes, and Coastal Landforms

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