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OrogenyOrogeny, , EpeirogenyEpeirogeny, Climate, Climate--Glaciers, Glaciers, IsostasyIsostasy & & EustacyEustacy Favor Glacial Systems, Favor Glacial Systems, Colluvial Systems, & Colluvial Systems, & Clastic SedimentsClastic Sediments
Ice-Age Systems = So Dynamic that Equilibria May Never Be Reached
Coastal Geomorphology
Seaside, Oregon
S. Kite Photo
1. Volume of Water in Oceans
Volcanic Degassing + Comet Capture Global Ice VolumeTemperature of Water
Long-Term Variations in Sea Level
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Solomon Island Sea-Level Change
2. Other FactorsEpirogeny: Ocean-Basin Geometry
Spread Rate at Divergent Plate BoundariesIsostacy
IceWater
Long-Term Variations in Sea Level
No "Global Sea Level Record Exists in One Place
Tectonically Emergent Coasts Are Most Often Used.
Oxygen Isotopes in Benthic Foraminifera Serve as Proxy Record of Ice-Ocean Volume
Long-Term Variations in Sea Level
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Short-Term Variations in Sea Level
Tides Wind Waves Storm SurgesSeismic Sea Waves (Tsunami)
• Gravity of the Moon and Sun Acting on Ocean Surface
• 24 Hr 50 Min: 2 Highs, 2 Lows
Lunar (Solar) Tides
Tides - Why?
• Spring Tide = Highest High Tide
• Neap Tide = Least Tide Range
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Why is there a
high tide on the earth
opposite of the
moon?
Why is there a
high tide on the earth
opposite of the
moon?
Think “Bolo”
Basin Shape & Size May Reduce or Enhance Tides
• Constrictions Reduce Tide Range (e.g. Mediterranean & Black Seas)
• Funnel-Shaped Basins Enhance Tide Range (e.g. Gulf of Maine, Bay of Fundy)
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Mediterranean Sea SSTs
Gulf of Maine Aquariumhttp://octopus.gma.org/surfing/schools/med_512_512.gif
Straits of Gibraltar
Gilbralterat Rising
Tide
Tidal Bore
Note Funnel Shape of Gulf of Maine & Bay of Fundy
Cold Water
Warm Water
Gulf of Maine
Gulf of Maine Aquarium: http://octopus.gma.org/surfing/summary.html
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NASA EarthKamhttp://earthkam.sdsc.edu/datasys/STS099/00235653/SATIMG.HTM
“Mongo” Tides (25,000,000 cms)
Bay of Fundy
Gulf of Maine
Acadia NP
Minas Basin
ChighectoBay
15 m Tides“Quoddy“ Bay
8 m Tides
Reversing Falls, St. John, New Brunswicknew-brunswick.net/.../reversingfalls/ images/stjh235.jpg
Albemarle, Pamlico SoundsWind Tides
L
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Albemarle, Pamlico SoundsWind Tides
L
Annual Tides
Produced by Seasonal Variations in
Prevailing Wind (Atmo Pressure) Water Density (Salinty, Temp)Oceanic Currents Continental Runoff
Wind -Creates Most Ocean Waves
Wave Height is Controlled by 1. Wind Velocity 2. Fetch = Distance Water Surface is Subjected to Wind
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1. Wind Waves
Typical Amplitude = < 20 Mλ (Wave Length) = < 300 M
Wave "Size" Is a Product of Wind Velocity, Fetch.
Velocity Fetch Height10 m/s 200 km 2.1-2.4 m10 1000 2.4-2.7 30 200 10-1230 1000 15-19
Wind Waves
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Evolution of Waves Approaching Shore
Deep Water (Hs > λ/2):Sinusoidal, Oscillatory Waves w/ Circular Motion = Swell
λinfHinf (Amplitude)Hs (Depth)
Wave Base = λinf / 2
Perfect Storm Image
Evolution of Waves Approaching ShoreTransition to Oval Motion Begins When Hs < λinf / 2
SurfSurf
SwashSwash
•• Wave BaseWave Base
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Beach TermsSwashSwash SurfSurf BreakersBreakers
BermBermOld Old BermBerm
Type of Breaking Waves Varies w/ Wave Height & Beach Slope
(See Figure 13.9 in Ritter & others, 1995)Wave Ht. Beach Slope Wave TypeSteep Gentle Spilling
Spilling Wave from Dr. Pål F. Lader’s Web Page
http://www.marin.ntnu.no/~lader/hoved_side/hoved_side.htm
Type of Breaking Waves Varies w/ Wave Height & Beach Slope(See Figure 13.9 in Ritter & others, 1995)Wave Ht. Beach Slope Wave TypeSteep Gentle SpillingIntermediate Intermediate Plunging
Surfer's Delight
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Type of Breaking Waves Varies w/ Wave Height & Beach Slope
(See Figure 13.9 in Ritter & others, 1995)Wave Ht. Beach Slope Wave TypeSteep Gentle SpillingIntermediate Intermediate Plunging
Surfer's DelightTransitional Collapsing
Shallow Steep Surging
Other Types of Waves (= Short-Term Variations in Sea-Level)
Seismic Sea Waves (Tsunami)
Open Ocean: Shallow WaterHinf < 10 m Hinf = 30 m
or Much More, e.g Alaska ‘64
λinf = 150-200 km λinf = Few kmVelocity < 800 km/h V = ~50 km/h
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Tusnami-Triggered LandslidesLituya Fiord, Alaska
Landslides
Storm Surges
Tropical Storm Very Low Barometric Pressure
Hinf < 5 m λ = 50-100 km
Hurricane Fran 1996
What is the Deadliest Day in US History?
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Isaac’s Storm:
The 1900 “Galveston”Hurricane
Galveston Hurricane 8 Sept.1900 Storm Surge
Galveston, Texas, 1900> 8000 Dead
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Wave Erosion-Deposition Processes
• Refraction• Longshore Current• Londshore Drift
Wave Refraction
Wave Refraction
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Longshore Current & Longshore Drift
Longshore Current & Longshore Drift
LSCLSC
Shoreline Erosion Rates: Eastern USA
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Headland Erosion
Coastal Geomorphology
CoastlinesPrimary: Relict from Other
Geomorphic Systems vs.
Secondary: Product of Coastal Processes
Primary v. Secondary Coasts• Both Examples from California
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Primary(Glaciated)
CoastCape
Breton IslandNova Scotia
Mid-Atlantic Coast:
Mix of Primary & Secondary Landscapes
Cite Examples from this Map
Bathymetry Chesapeake Bay:
Paleo-Susquehanna
River
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Wind Tides - Pamlico Sound,
Albemarle Sound, NC
BetsibokaEstuary and
Delta, Madagascar
Sediment Plume
Po River Delta, Italy
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Nile River Delta
Barrier Island Spit, South Carolina
Variations in Hog Island, Virginia,
Since 1852
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Cape Hatteras
Lighthouse, 1997
Washover: Before
After Hurricane Fran, 1996
Damage From Hurricane Fran, 1996, NC
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Presque Isle, Lake Erie, PA,image courtesy Chris Schaney
Coastal Structures
• Spit• Groin• Jetty
Rocky Coasts: Wave-Cut Landforms
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Ecola State Park, Oregon
PocketBeach
Indian PointHeadland
S. Kite Photo
Topo MapEcola State Park
Oregon
Indian Beach, Oregon
Headland
S. Kite Photo
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Indian Beach, Oregon
S. Kite Photo
Wave-Cut NotchLion Rock?, Oregon
S. Kite Photo
Monument cove, Acadia NP, Maine
Seastack: Haystack Rock, Cannon Beach, Oregon
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Percé Rock, Gaspé, P.Q.
www.neseabirds.com/ gaspe.htm
Sea Arch
Bluff & Wave-Cut Platform
Tombolo, So. California
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Living at Risk, So. California
Baymouth Bar, So. Calif.
Landforms
MarineTerraces
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Reefs Fringing Volcano
Atoll
Sinking of Cool, Dense Plates
Seamount
Sinking of Cool, Dense Plates
Volcanic Island
Spreading Direction
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Sinking of Cool, Dense Plates
Erosion of Volcanic Island
Spreading Direction
Sinking of Cool, Dense Plates
Erosion Below Wave Base Forms
GuyotGuyot
Spreading Direction
Sinking of Cool, Dense Plates
GuyotGuyot Subsides Subsides with Cooling Platewith Cooling Plate
Spreading Direction
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Sinking of Cool, Dense Plates
GuyotGuyot Subsides Subsides with Cooling Platewith Cooling Plate
Spreading Direction
Eroding Volcanoes with Fringing Reefs
Society Islands
Atoll
MaldiveIslands: Coral Reefs
NASA
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PenhyrnAtoll, Cook
Islands
NASA
Tuamotu Archipeligo AtollsNASA