Seaside, Oregonpages.geo.wvu.edu/~kite/Geo321Lect24a_2006CoastalI.pdfType of Breaking Waves Varies...

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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