Coastal Landforms. Basic Concepts I. Sea level changes repeatedly 422 ft. eustatic rise since 18,000...
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Coastal Landforms
Coastal Landforms. Basic Concepts I. Sea level changes repeatedly 422 ft. eustatic rise since 18,000 years ago. specific landscapes submergent or emergent
Basic Concepts I. Sea level changes repeatedly 422 ft. eustatic
rise since 18,000 years ago. specific landscapes submergent or
emergent depending on tectonic change II. Waves and resultant
currents erode, transport, and deposit sediment load. rocky
headlands beaches III. Tides affect all coastal life but have
little topographic effect. tidal bores
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Eustatic Change and Submergent vs. Emergent Coastlines during
ice ages sea level sinks as ocean water compresses and more water
is tied up in glaciers. During interglacial periods sea level
rises, flooding many former river valleys creating bays and
estuaries. In areas with rapid tectonic uplift emergent cliffs
common and bays rare.
Slide 5
Submergent Coastlines Sea level rise inundated many coastal
valleys creating bays and estuaries. These coasts are referred to
as ria coastlines. Estuary - An arm of the sea that extends inland
to meet the mouth of a river.
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Emergent Coastlines Tectonic forces lift coastlines faster than
sea- level rises. Dramatic cliffs and marine terraces tower above
the sea.
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COASTAL FLUVIAL PROCESSES/LANDFORMS Coastal Erosion - dependent
on wave size, angle, and frequency. Focused where waves contact
coast. Headlands, sea cliffs, bluffs, sea stacks, natural bridges
Beach Erosion Coastal Transportation - wave action creates strong
currents parallel to shore. Large waves move beach sand offshore.
Small waves push it back on shore. Longshore current Coastal
Deposition where wave action is reduced, beaches and dunes form.
beaches dunes sand spits
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Isla Vista Beach, October 2001
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Isla Vista Beach, December 2002
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Beach Erosion
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Marine Terraces
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Point Reyes National Seashore
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Wave Refraction - waves change directional trend as they
approach shore. Raglan, New Zealand
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Tombolo
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Sand Spit
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Sea Stacks
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Natural Bridges and Arches
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Barrier Islands
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Outer Banks, North Carolina
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Tropical Coasts
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Factors Correlated with Healthy Coral Reef Growth water
temperature range: 18 29 C normal seawater salinity: 32 35 clear,
transparent water little or no sedimentation vigorous water
motion
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Tropical Mangroves
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Mangroves create tidal forests. These rich ecosystems provide
habitat for countless creatures and help to stabilize and, by
catching sediment, even create coastline.
Slide 44
Tides Tides rise and fall with the rising moon, an interval of
24 hours and 50 minutes. There is a bulge on both sides of the
earth. Thus two high tides each cycle. Flood tide (low to high)
takes 6:13 and then ebb tide (back to low) is another 6:13.
Slide 45
Tides Tide range dependent on relative position of earth, moon,
and sun. Spring Tides - highest tidal range Neap Tides - lowest
tidal range
Slide 46
Tides Tide range dependent on relative position of earth, moon,
and sun. Spring Tides - highest tides. Neap Tides - lowest tides.
Full Moon Half Moon
