Coastal Geology and Sediment Dynamics
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Coastal Geology and Sediment Dynamics

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Questions and Answers

What geological feature is formed when the arch of a coastal rock structure collapses?

  • Spit
  • Cliff
  • Stack (correct)
  • Bay
  • Which process primarily leads to the formation of a beach?

  • Underwater currents
  • Deposition by constructive waves (correct)
  • Glacial activity
  • Erosion by waves
  • What distinguishes a shingle beach from a sand beach?

  • Sand beaches are narrower and steeper.
  • Sand beaches have more vegetation.
  • Shingle beaches have larger particles and are steeper. (correct)
  • Shingle beaches are wider and flatter.
  • Which of the following is NOT a characteristic of a beach?

    <p>Stacks</p> Signup and view all the answers

    How does a spit form?

    <p>By longshore drift depositing material across a river mouth</p> Signup and view all the answers

    What is the term for a spit that has a curved end?

    <p>Recurved spit</p> Signup and view all the answers

    Which coastal feature forms when spits join two headlands together?

    <p>Tombolo</p> Signup and view all the answers

    What usually forms in the area behind a spit?

    <p>Mudflats or saltmarshes</p> Signup and view all the answers

    What impact does sea level rise have on fresh water bodies near the coast?

    <p>It increases salinity, making the water unsuitable for many uses.</p> Signup and view all the answers

    Which coastal area experienced an increase in flooding events from 1995 to 2014?

    <p>Kings Point</p> Signup and view all the answers

    What percentage of Bangladesh's land would be lost with just a 0.3m rise in sea level?

    <p>6%</p> Signup and view all the answers

    What is a characteristic of low-energy coastlines?

    <p>They are protected by coral reefs or islands.</p> Signup and view all the answers

    Which of the following is NOT a consequence of coastal erosion?

    <p>Creation of wave-cut platforms</p> Signup and view all the answers

    What are raised beaches formed from?

    <p>Former wave-cut platforms that are now above current sea level</p> Signup and view all the answers

    What indicates a positive sediment budget at a coastline?

    <p>More sediment enters the coastal system than leaves.</p> Signup and view all the answers

    Which coastal area is projected to have the highest flood costs by 2050?

    <p>Guangzhou</p> Signup and view all the answers

    How are sediment cells characterized?

    <p>They have clear boundaries that allow for balanced erosion and deposition.</p> Signup and view all the answers

    What feature is formed when sea level rises and partially submerges river valleys?

    <p>Rias</p> Signup and view all the answers

    Which process involves the compression of air in cracks of cliffs by waves?

    <p>Hydraulic Action</p> Signup and view all the answers

    What happens during cavitation in coastal erosion?

    <p>Compressed air violently expands when waves recede.</p> Signup and view all the answers

    What happens to the coastal ecosystems as a result of increased storms and erosion?

    <p>They face significant damage and loss of habitat.</p> Signup and view all the answers

    Which of the following is NOT a way waves erode the coastline?

    <p>Transportation</p> Signup and view all the answers

    What contributes to the formation of estuaries in coastal systems?

    <p>Sea level rise flooding river valleys.</p> Signup and view all the answers

    What is a primary characteristic of abrasion in coastal erosion?

    <p>It involves rocks and sediment grinding against each other.</p> Signup and view all the answers

    What characterizes the depth of fjords compared to other coastal landforms?

    <p>They have very steep sides and can exceed 500 m in depth.</p> Signup and view all the answers

    Which statement about the processes affecting coastal landscapes is accurate?

    <p>Active and relict landforms can coexist within coastal landscapes.</p> Signup and view all the answers

    How are dalmatian coastlines formed?

    <p>Through flooding of low-lying areas parallel to the coast.</p> Signup and view all the answers

    What factors influence the selection of areas for coastal management?

    <p>The economic viability of protecting settlements.</p> Signup and view all the answers

    What impact can a change in coastal processes have on landforms?

    <p>It can shift a landscape from erosion-dominated to deposition-dominated.</p> Signup and view all the answers

    What is meant by 'relict landforms' in coastal landscapes?

    <p>Landforms that date back to a past geological period but are still affected by coastal processes.</p> Signup and view all the answers

    What depth can notable fjords like Sognefjorden reach?

    <p>Over 1000 m.</p> Signup and view all the answers

    How do coastal landscapes change over time?

    <p>Changes can occur both gradually over years and suddenly due to events like storms.</p> Signup and view all the answers

    What is a potential disadvantage of using gabions for coastal protection?

    <p>They are not very strong.</p> Signup and view all the answers

    Groynes are effective at trapping material transported by what process?

    <p>Longshore drift</p> Signup and view all the answers

    Which feature of breakwaters can also act as a pedestrian walkway?

    <p>The connection to land</p> Signup and view all the answers

    Why might the placement of a groyne be crucial?

    <p>It can lead to rapid erosion behind it.</p> Signup and view all the answers

    What is one ecological concern associated with breakwaters?

    <p>They can cause sediment build-up harming ecosystems.</p> Signup and view all the answers

    Tidal barriers are particularly useful for managing what natural phenomenon?

    <p>Storm surges</p> Signup and view all the answers

    Which of the following is a drawback of using groynes?

    <p>They only last for 50 years.</p> Signup and view all the answers

    What is the primary purpose of riprap in coastal management?

    <p>To absorb wave energy and reduce erosion.</p> Signup and view all the answers

    Study Notes

    Coastal Dynamics

    • Low-energy coastlines are often shielded by coral reefs or islands, resulting in fewer wave impacts.
    • These coastlines feature salt marshes and tidal mudflats, where sediment accumulation exceeds erosion, promoting land growth.
    • Coastal sediment inputs arise from river sedimentation, sea level rise forming estuaries, cliff erosion, and marine organism shell degradation.
    • The sediment budget assesses sediment balance: a positive budget indicates land extension, while a negative budget shows coastline retreat.

    Sediment Cells

    • The coastline is segmented into sediment cells, which balance erosion and deposition.
    • Sub-cells exist with specific material inputs and defined boundaries like headlands; theoretically, these operate as closed systems, but practical transfers may occur.

    Erosion Processes

    • Erosion occurs through various mechanisms:
      • Abrasion: Wave-transported materials grind against coastal structures.
      • Hydraulic Action: Waves compress air in cliff cracks, expanding pressure causes rock breakage.
      • Cavitation: The release of compressed air from waves further erodes rock.
      • Wave Quarrying: The force of waves detaches rock pieces from cliffs.

    Coastal Landforms

    • Beaches form from constructive wave action depositing sand or shingle.
      • Shingle Beaches: Steep and narrow, composed of larger particles.
      • Sand Beaches: Wide and flat, made from smaller particles.
      • Distinctive beach features include:
        • Berms: Ridges marking the high-tide line.
        • Runnels: Sand grooves parallel to the shore.
        • Cusps: Crescent-shaped markings on mixed beaches.

    Spits and Bars

    • Spits: Sand and shingle formations extending into the sea due to shifting coastal directions, with variations like simple, recurved, and compound spits.
    • Offshore Bars: Form as materials accumulate in shallow areas, sometimes creating lagoons behind.

    Impacts of Climate Change

    • Increasing storm frequency and intensity heightens risks to coastal ecosystems and infrastructures.
    • Rising sea levels lead to severe flooding, exemplified by Kings Point, NY, experiencing doubling flood events within a decade.
    • Projected land loss includes significant areas in Bangladesh and the Maldives with minimal sea level rise.
    • Saltwater intrusion threatens freshwater resources and agricultural viability, necessitating increased flood protection funding.

    Coastlines of Emergence

    • Sea level fall unveils new landforms:
      • Raised Beaches: Higher-level beaches developed from sediment accumulation.
      • Wave-Cut Platforms: Exposed surfaces from eroded former shorelines.
      • Relict Cliffs: Vegetative recovery of formerly coastal cliffs.

    Coastlines of Submergence

    • Sea level rise results in submerged landscapes:
      • Rias: Partially submerged river valleys.
      • Fjords: Drowned glacial valleys with steep cliffs.
      • Dalmatian Coastlines: Parallel islands formed by rising sea levels flooding valleys.

    Coastal Management Techniques

    • Coastal management aims to mitigate erosion and flooding impacts on populations and environments, often prioritizing urban areas for resource allocation.
    • Riprap: Large rocks placed along shores to absorb wave energy, economically viable but may restrict access.
    • Groynes: Structures installed to capture drifted materials, wider beaches offer better protection but can lead to downstream erosion.
    • Breakwaters: Built offshore to reduce wave energy and protect coastlines, but can incur ecological costs.
    • Tidal Barriers: Mechanisms across river estuaries prevent floodwaters during storms, enhancing community resilience.

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    Description

    Explore the dynamics of low-energy coastlines influenced by coral reefs and islands. This quiz covers sediment sources, deposition, and coastal erosion processes. Test your knowledge on how these factors shape coastal systems.

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