Coastlines

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Coastlines

• Sealevel changes
• Coastal features
• Interactions of humans along coasts

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Sealevel Changes

• Global changes in water level (Eustatic)
• Changes in VOLUME OF WATER
• Changes in SHAPE OF BASIN

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Sealevel changes

• Localized changes in position of continent
• TECTONIC changes
• ISOSTATIC changes due to weight

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Place where tectonic changes are likely
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Erosional coasts cliffs, drowned river valleys
as examples
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Depositional coasts deltas, barrier
islands, mudflats as examples
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Beach Physical features (1)
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Beaches physical features (2)

• Backshore begins at cliff or dunes ends at berm
• Foreshore berm to out past low tide level
• Offshore seaward of low tide level to end of
  wave action

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Erosion and deposition along beaches longshore
transport
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Erosion and deposition along beaches summer vs.
winter
Summer
Winter
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Water circulation along beaches longshore current
Waves strike at an angle
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Water circulation along beaches rip currents
water piles up along the beach and has to escape
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Beaches human interactions

• Dams source of sediments is interrupted
• Seawalls
• Breakwaters
• Jetties
• Groins
• Replenishment (renourishment)

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Jetties
Groins
Breakwater
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Features of Barrier Islands

• Beach
• Dunes
• Barrier flats
• Salt marsh

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(No Transcript)
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Barrier islands salt marshes

• High marsh
• Juncus (reed)
• Salicornia (succulent)
• Low marsh
• Regularly covered and uncovered
• Spartina of varying heights
• Importance of marshes

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Migration of barrier islands

• Movement with sealevel
• Erosion and deposition

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Estuaries

• Where rivers meet the sea
• Embayment
• Mixing of salt and fresh water
• Protected from waves and storms
• Good harbors

Chesapeake Bay
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Estuaries formation

• Coastal plain Chesapeake Bay
• Fjord Puget Sound
• Bar-built Pamlico Sound
• Tectonic San Francisco Bay

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COASTAL PLAIN
FJORD
BAR BUILT
TECTONIC
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Estuaries circulation

• Salt wedge strong river
• Well mixed strong tides
• Fjord special circumstances
• Think about salinity variation with depth

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Salt wedge
Well mixed
Fjord
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Environmental issues along coastlines

• Human interactions along beaches
• Wetlands
• Water quality
• Plastics
• Oil spill
• (as examples)