Orogeny, Epeirogeny,, Climate-Glaciers, Isostasy & Eustacy Favor Glacial Systems, Colluvial Systems, & Clastic Sediments Ice-Age Systems = So Dynamic that Equilibria May Never Be Reached Seaside, Oregon Coastal Geomorphology S. Kite Photo Long-Term Variations in Sea Level 1. Volume of Water in Oceans Volcanic Degassing + Comet Capture Global Ice Volume Temperature of Water 1
Solomon Island Sea-Level Change Long-Term Variations in Sea Level 2. Other Factors Epirogeny: Ocean-Basin Geometry Spread Rate at Divergent Plate Boundaries Isostacy Ice Water 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 2
Short-Term Variations in Sea Level Tides Wind Waves Storm Surges Seismic Sea Waves (Tsunami) Lunar (Solar) Tides Gravity of the Moon and Sun Acting on Ocean Surface 24 Hr 50 Min: 2 Highs, 2 Lows Tides - Why? Spring Tide = Highest High Tide Neap Tide = Least Tide Range 3
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) 4
Mediterranean Sea SSTs Straits of Gibraltar Gulf of Maine Aquarium http://octopus.gma.org/surfing/schools/med_512_512.gif Tidal Bore Gilbralter at Rising Tide Note Funnel Shape of Gulf of Maine & Bay of Fundy Cold Water Gulf of Maine Warm Water Gulf of Maine Aquarium: http://octopus.gma.org/ surfing/summary.html 5
Mongo Tides (25,000,000 cms) Quoddy Bay 8 m Tides Bay of Fundy Chighecto Bay 15 m Tides Minas Basin Acadia NP Gulf of Maine NASA EarthKam http://earthkam.sdsc.edu/datasys/sts099/00235653/satimg.htm Reversing Falls, St. John, New Brunswick new-brunswick.net/.../reversingfalls/ images/stjh235.jpg Albemarle, Pamlico Sounds Wind Tides L 6
L Wind Tides Albemarle, Pamlico Sounds 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 7
1. Wind Waves Typical Amplitude = < 20 M λ (Wave Length) = < 300 M Wave "Size" Is a Product of Wind Velocity, Fetch. Velocity Fetch Height 10 m/s 200 km 2.1-2.4 m 10 1000 2.4-2.7 30 200 10-12 30 1000 15-19 Wind Waves 8
Evolution of Waves Approaching Shore Deep Water (Hs > λ/2): Sinusoidal, Oscillatory Waves w/ Circular Motion = Swell λ inf H inf (Amplitude) H s (Depth) Wave Base = λ inf / 2 Perfect Storm Image Evolution of Waves Approaching Shore Transition to Oval Motion Begins When Hs < λ inf / 2 Swash Surf Wave Base 9
Swash Beach Terms Surf Breakers Old Berm Berm Type of Breaking Waves Varies w/ Wave Height & Beach Slope (See Figure 13.9 in Ritter & others, 1995) Wave Ht. Beach Slope Wave Type Steep 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 Type Steep Gentle Spilling Intermediate Intermediate Plunging Surfer's Delight 10
Type of Breaking Waves Varies w/ Wave Height & Beach Slope (See Figure 13.9 in Ritter & others, 1995) Wave Ht. Beach Slope Wave Type Steep Gentle Spilling Intermediate Intermediate Plunging Surfer's Delight Transitional Collapsing Shallow Steep Surging Other Types of Waves (= Short-Term Variations in Sea-Level) Seismic Sea Waves (Tsunami) Open Ocean: H inf < 10 m λ inf = 150-200 km Velocity < 800 km/h Shallow Water H inf = 30 m or Much More, e.g Alaska 64 λ inf = Few km V = ~50 km/h 11
Tusnami-Triggered Landslides Lituya Fiord, Alaska Landslides Storm Surges Tropical Storm Very Low Barometric Pressure H inf < 5 m λ = 50-100 km Hurricane Fran 1996 What is the Deadliest Day in US History? 12
Isaac s Storm: The 1900 Galveston Hurricane Galveston Hurricane 8 Sept.1900 Storm Surge Galveston, Texas, 1900 > 8000 Dead 13
Wave Erosion-Deposition Processes Refraction Longshore Current Londshore Drift Wave Refraction Wave Refraction 14
Longshore Current & Longshore Drift Longshore Current & Longshore Drift LSC Shoreline Erosion Rates: Eastern USA 15
Headland Erosion Coastal Geomorphology Coastlines Primary: Relict from Other Geomorphic Systems vs. Secondary: Product of Coastal Processes Primary v. Secondary Coasts Both Examples from California 16
Primary (Glaciated) Coast Cape Breton Island Nova Scotia Mid-Atlantic Coast: Mix of Primary & Secondary Landscapes Cite Examples from this Map Bathymetry Chesapeake Bay: Paleo- Susquehanna River 17
Wind Tides - Pamlico Sound, Albemarle Sound, NC Betsiboka Estuary and Delta, Madagascar Sediment Plume Po River Delta, Italy 18
Nile River Delta Barrier Island Spit, South Carolina Variations in Hog Island, Virginia, Since 1852 19
Cape Hatteras Lighthouse, 1997 Washover: Before After Hurricane Fran, 1996 Damage From Hurricane Fran, 1996, NC 20
Presque Isle, Lake Erie, PA, image courtesy Chris Schaney Spit Groin Jetty Coastal Structures Rocky Coasts: Wave-Cut Landforms 21
Ecola State Park, Oregon Indian Point Headland Pocket Beach S. Kite Photo Topo Map Ecola State Park Oregon Indian Beach, Oregon Headland S. Kite Photo 22
Indian Beach, Oregon S. Kite Photo Wave-Cut Notch Lion Rock?, Oregon S. Kite Photo Monument cove, Acadia NP, Maine Seastack: Haystack Rock, Cannon Beach, Oregon 23
Percé Rock, Gaspé, P.Q. www.neseabirds. com/ gaspe.htm Sea Arch Bluff & Wave-Cut Platform Tombolo, So. California 24
Living at Risk, So. California Baymouth Bar, So. Calif. Marine Terraces Landforms 25
Reefs Fringing Volcano Atoll Sinking of Cool, Dense Plates Seamount Sinking of Cool, Dense Plates Volcanic Island Spreading Direction 26
Sinking of Cool, Dense Plates Erosion of Volcanic Island Spreading Direction Sinking of Cool, Dense Plates Erosion Below Wave Base Forms Guyot Spreading Direction Sinking of Cool, Dense Plates Guyot Subsides with Cooling Plate Spreading Direction 27
Sinking of Cool, Dense Plates Guyot Subsides with Cooling Plate Spreading Direction Atoll Eroding Volcanoes with Fringing Reefs Society Islands Maldive Islands: Coral Reefs NASA 28
Penhyrn Atoll, Cook Islands NASA Tuamotu Archipeligo Atolls NASA 29