USA Coastal Cliffs & Wave-Cut Platforms Quiz
Pacific Coast erosion landforms (10 questions).
USA Coastal Cliffs & Wave-Cut Platforms Quiz: Quick Study Notes
Explore the dynamic geological processes shaping the Pacific Coast of the United States. This section provides a concise overview of the erosional landforms, such as towering sea cliffs and expansive wave-cut platforms, that characterize this active margin, highlighting the powerful interaction between ocean waves and land.
Key Concepts
Key Takeaways
- The Pacific Coast is an active margin, influencing rapid erosion and the formation of distinctive coastal landforms.
- Sea cliffs form through persistent wave erosion at their base, which undercuts the rock and causes periodic collapses.
- Wave-cut platforms are horizontal rocky surfaces created by the retreat of sea cliffs due to wave action, often visible at low tide.
- The intensity of wave energy, along with the resistance of geological materials, determines the rate and extent of coastal erosion.
- Differential erosion leads to the formation of varied features like headlands (resistant rock) and bays (softer rock).
- Tectonic uplift plays a crucial role by exposing older wave-cut platforms, creating marine terraces that indicate past sea levels.
Frequently Asked Questions
What is the primary process forming sea cliffs on the Pacific Coast?
Sea cliffs are primarily formed by wave erosion (hydraulic action and abrasion) at their base, which undercuts the cliff face, leading to collapses and the cliff’s retreat.
How does a wave-cut platform develop?
A wave-cut platform develops as waves erode the base of a cliff, creating a notch. As the cliff retreats, the eroded bedrock at sea level forms a broad, flat, rocky surface, often exposed at low tide.
Why is the Pacific Coast of the USA particularly prone to cliff erosion?
The Pacific Coast is an active tectonic margin, experiencing uplift that exposes marine terraces and relatively soft sedimentary rocks to intense wave action, leading to significant erosion and cliff formation.
What is the significance of differential erosion in shaping coastal landforms?
Differential erosion occurs when varying rock types erode at different rates. Resistant rocks form headlands, while softer rocks erode faster, creating bays, influencing the irregular shapes of cliffs and platforms.
Can wave-cut platforms indicate past sea levels?
Yes, raised wave-cut platforms, also known as marine terraces, are significant indicators of past sea levels relative to land, as they represent former sea-level stands that have been tectonically uplifted.
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