NOTES
Links to summaries of key issues for each topic
VISUALS
Links to images employed in lectures on a topic-by-topic basis
TEXT
Link to chapter outlines at online learning center at McGraw Hill.
NOTES
Links to summaries of key issues for each topic
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Coasts, Beaches and Estuaries
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Notes on Topic:
The notes represent summaries of key issues
for each topic
They emphasize the terminology used to describe
the various phenomena.
| 1. Coastal Zones: |
| Learning Objectives: |
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Comprehension of the features associated with coastlines
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Understanding of the factors that govern coastal characteristics
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| Forms and Types of Coasts: |
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Forms of coastline:
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cliffs, dunes, beaches, bays, coves, river mouths and the ocean.
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shore: region extending out to limit of wave action
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beach: accumulation of sediment affected by coastal processes.
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Types of coasts:
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landforms and processes: geomorphology
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modified by sea level changes
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affected by rivers, currents, storms, ice, corals
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coastal characteristics are governed by either land or ocean processes:
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land - primary coasts:
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erosion by water, wind, ice, sea level
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sediments from rivers, wind, glaciers
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volcanic activity, e.g. lava flow
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earth movements, e.g. earthquakes;
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ocean - secondary coasts:
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erosion due to waves, currents, seawater
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deposition of sediments by waves, tides, currents
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alteration by marine plants and animals
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| Primary Coasts: |
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U-shaped valleys carved by glaciers: fjords.
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often with a shallow sill at entrance
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moraine formed from debris deposited by glacier when it retreated
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V-shaped valleys formed from river valleys drowned by sea-level rise
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Deltas:
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sediment deposits from suspended load at river mouths
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alluvial plains formed by sediment deposits.
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Dune coasts:
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wind modified formed by migration of sand
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Lava coasts, cratered coasts:
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shaped by volcanic deposits and processes
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Tectonic Coasts:
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| Secondary Coasts: |
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Produced by marine processes of deposition and erosion
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Cliffs, or pinnacles, sea stacks
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Eroded materials may form bars, barrier islands, sand spits, hooks
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Reef coasts: biological influence
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Mangroves and salt marshes:
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plants retain sediments
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periodically flooded by tides.
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| 2. Beaches: |
| Learning Objectives: |
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Appreciation of beach characteristics and approaches to their description
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Understanding of the dynamic forces that shape and change beaches over
time
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| Characteristics: |
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Shoreline divided into zones:
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offshore, inshore (where breakers occur)
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foreshore (low to high tide)
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backshore (affected by storms)
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typical features:
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sand bars, longshore bars and troughs, (parallel to coastline)
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summer and winter berms (high tide crest)
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changed by storms and storm surges
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requires strength to erode & deposit
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wave-cut scarps, terraces, longshore bars and troughs.
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Beaches are described by:
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shape and structure:
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whether wide or narrow, steep or flat, long or discontinuous,
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spits and tombolos
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composition (sand, coral, shells, lava)
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size (mud, sand, pebbles)
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depend on processes and forces acting on beach
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lag deposits, armored beach.
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color:
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white, black, green, pink sands.
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| Beach Dynamics: |
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A dynamic equilibrium between depositional and erosion processes
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differs from summer to winter.
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Motion of water:
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onshore current creates surf zone
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longshore current parallel to shore moves sediment
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longshore transport within drift zone
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up-rush of waves: swash, may form cusps.
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Accreting regions where deposition occurs
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rip current carry sediment away as part of coastal circulation.
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Sediment budgets of beaches can be described as littoral cells
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sand accumulates or is lost by offshore transport, or wind.
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Department
of Geological Sciences,
1001
E. Tenth Street, Bloomington, IN 47405-1403
Phone:
(812) 855-5582 Last updated: 7 December 2000
Comments:
simon@indiana.edu
Copyright
2000, The Trustees of Indiana University
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