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
Gulf of Maine Aquarium: http://octopus.gma.org/ surfing/summary.html Warm Water
5 “Mongo” Tides (25,000,000 cms)
Chighecto 15 m “Quoddy“ Bay Bay Tides 8 m Tides n asi y s B ina Fund M of y Ba
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
Wind Tides LAlbemarle, Pamlico Sounds
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
λinf
Hinf (Amplitude)
Hs (Depth)
Wave Base = λinf / 2
Perfect Storm Image
Evolution of Waves Approaching Shore
Transition to Oval Motion Begins When Hs < λinf / 2 Swash
Surf
• Wave Base
9 Beach Terms Swash 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: Shallow Water
Hinf < 10 m Hinf = 30 m or Much More, e.g Alaska ‘64
λinf = 150-200 km λinf = Few km Velocity < 800 km/h V = ~50 km/h
11 Tusnami-Triggered Landslides Lituya 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?
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
Coastal Structures
• Spit • Groin • Jetty
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.
Landforms
Marine Terraces
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
Eroding Volcanoes with Fringing Reefs Society Islands
Atoll
Maldive Islands: Coral Reefs
NASA
28 Penhyrn Atoll, Cook Islands
NASA
Tuamotu Archipeligo Atolls NASA
29