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Introduction to Coastal Process

Introduction to Coastal Process. Introduction. ½ world’s population in coastal regions Coastal modification impacts humans and other organisms/plants Present-day climate change will modify coasts. LA Times. Class Focus. Shaping of Coastline Processes operating on coastline

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Introduction to Coastal Process

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  1. Introduction to Coastal Process

  2. Introduction • ½ world’s population in coastal regions • Coastal modification impacts humans and other organisms/plants • Present-day climate change will modify coasts LA Times

  3. Class Focus • Shaping of Coastline • Processes operating on coastline • Changes along the coast

  4. More Specific Class Focus • Geology influence on coastal features • Nearshore processes • Fluvial processes • Sea level and climate • Sediment transport

  5. Some Terminology • Shore • Zone between low tide level & upper level of wave action. In our coasts, usually cliffs • Consists of foreshore, backshore, and nearshore

  6. Terminology • Shoreline • Water’s edge • Beach • Loose sediment (sand, gravel, boulders) accumulation • Mostly in backshore • Coast • Includes shores & nearshore to where waves break • Inland to where marine influences cease—cliffs, lagoons etc • Will vary in width • Where air, sea, water mix • Influenced by • Tectonics and lithology • Oceanographic processes—waves, tides, current • Sea level • Atmospheric processes—wind, precipitation • Coasts shaped by • Erosion • Deposition

  7. Ancient Coastlines • Sedimentary geologists • Reconstruct sedimentary environments • Ancient shorelines preserved throughout rock record • Help reconstruct ancient sea level rise and fall • Global record vs local record • Climate vs tectonic activity Picasaweb.com Oysters, Vaqueros Fm.

  8. Shape of coastlines • Straight or curved • E.g. san Andreas Fault in San Francisco area • Madura, Indonesia • East Madagascar Based on U.S. Geological Survey map

  9. Terminology • Coastline • Land margin at normal high tide • Difference between coastline and shoreline?

  10. Straight Coastlines • Madagasgar • Indonesia

  11. Some basic relationships • Headlands & promitories= resistant rocks • Bays = less resistant rock or tectonic folding, tilting • Embayed coastline with valley mouth usually submerged • E.g. east U.S. coast • Gulf coast formed by deposition = curved coast Marin Headlands, San Francisco area Photo (c) Andrew Alden

  12. Gulf coast and Eastern Seaboard ECB.org NASA

  13. Rounded Bays • Submerged volcanoes • E.g. Santorini • Hanauma Bay, Oahu Hanauma Bay and Koko Crater at Koko Head, Oahu NASA

  14. Evolution of Coasts • Tectonic Processes • Separation of plates • Active tectonic processes—faulting and folding • Climate—wind, rain, weathering & decomposition, vegetation • Rising and falling tides

  15. Changing Coastline • Advancing • Sedimentation is greater than erosion • Emergence, uplift, sea level fall • Retreating • Erosion greater than deposition • Sea level rise • subsidence

  16. Rates of Coastline Change • Rapid • Storms • Lava flows • Earthquakes • Gradual • Longer termed changes • Tectonic uplift, sea level rise • Measure changing coastline • Maps, photographs, gps, etc.

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