GEOLOGY 101 Under the Boardwalk: Coastal Geomorphologypages.geo.wvu.edu/~kite/Geol101_2009Lect14-15...
Transcript of GEOLOGY 101 Under the Boardwalk: Coastal Geomorphologypages.geo.wvu.edu/~kite/Geol101_2009Lect14-15...
GEOLOGY 101 Under the Boardwalk:
Coastal Geomorphology
• What to look for while you're on the beach during spring break.
J.S. Kite, WVU
What Causes Changes in Sea Level?
• Answer Varies with Time Scale.
Long-Term Changes in Sea Level
• Shape and Volume of Ocean Basins – Varies with Sea-Floor Spreading Rates
• Slow Spreading = Deeper Ocean Basins• Fast Spreading = Shallower Ocean Basins &
Seas Spill on to Continents
• Volume of Glacier Ice ~225 ft Higher if All Glaciers Melt~400 ft Lower at Pleistocene Maximum
Sea Level Variation in Last 700,000 years
Long-Term Changes in Sea Level• Volume of Glacier Ice
– Pleistocene “Ice Age” 400-500 ft Lower
Estuaries =Drowned River
Valleys:
Delaware Bay, Cheaspeake Bay,Pamlico Sound,
Albemarle Sounds
Eroded During Glacial Low Sea-
Level Stands, Drowned During Interglacial High Sea-Level Stands
Chesapeake Bay
Bathymetry
Susquehanna Paleo-River
Last Century: Ocean Warming & Expansion, Glacial Melting
Seismic Sea Waves (Tsunami) Short
Term Changes
in Sea Level
• Seismic Sea Waves (Tsunami)
www.columbia.edu/itc/sipa/nelson/newmediadev/files/2004_Indonesia_Tsunami.gif
Boxing Day Tsunami Animation
Tsunami Animation Sites
Indonesia 2004http://iri.columbia.edu/~lareef/tsunami/#Tsunami_Animation:_National_Institute_of
Alaska Simulationhttp://nctr.pmel.noaa.gov/Titov/show/
Tides - Why?
• 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 & Lowest Low Tide
• Neap Tide =Less Tide Range
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 “Bolos”
Bolos
http://www.flight-toys.com/bola/bola_argentina10.jpg
Tides Can Be Enhanced or Reduced by the Shape and
Size of a Basin• Gulf of Maine, Bay of Fundy• Mediterranean Sea
The “Med” - Puny Tides
Straits of Straits of GibraltarGibraltar
Bay of Fundy-
“Mongo”Tides
Gulf of Maine-Bay of Fundy Tide Model Copyright � 2005 SMAST/ UMASSD
http://fvcom.smast.umassd.edu/research_projects/GB/Tidal_simulation/gb_tide_curr.gif
View this on line at http://fvcom.smast.umassd.edu/research_projects/GB/Tidal_simulation/gb_tide_curr.gif
What is Deadliest Day in U.S. History?
• San Francisco Quake, 1906 ~ 500 Dead?• Hurricane Katrina, 2005 1,836 Dead #• Johnstown Flood of 1889 ~ 2209 Dead?• Pearl Harbor, Dec 7 1941 ~ 2471 Dead #• 11 September 2001 ~ 2986 Dead #• November 1918 Flu ~ 3000 Every Day• Antietam, 17 Sept 1862 3650 Dead
(23,000 casualties. NPS: ~ 4000 may have died later)
• Issac’s Storm, 1900: ~ 8000 Dead in Galveston, Texas Alone!
# From Wikipedia, the free encyclopedia
Antietam/Sharpsburg 17 Sep 1862National Park Service Data
Casualties in 3 categories: 1) dead; 2) wounded; and 3) missing or captured.
Approximate Numbers Union Confederate TotalKilled 2,100 1,550 3,650
Wounded 9,550 7,750 17,300Missing/Captured 750 1,020 1,770
Total 12,400 10,320 22,720
• These are the approximate numbers for September 17th, 1862. No one knows the actual number of men who would later die of their wounds or the number of missing who had been killed. If you take a conservative estimate of 20% of the wounded dying of their wounds and 30% of the missing killed, the approximate number of soldiers that died as a result of this battle are 7,640.
Storm Surge
“Wave” created by low atmospheric pressure “sucking” ocean water into center of storm
Add pressure map for HurricanCamille
Powerful Low Pressure System (L) Generates Partial Vacuum that draws water into a large wave (storm surge)
31 October 2000 Upper-Air “Weather” Map from Environment Canada/ d ti /t h id / d l 9 t li d th j t t ht l
L
Isaac’s Storm:
The 1900 “Galveston”Hurricane
Galveston Hurricane 1900 Storm Surge Map
Tipped House, Galveston, 1900
Debris at Galveston,1900
Debris at Galveston,1900
Galveston, Texas, 1900
Total Destruction at Galveston, Texas, 1900
Lucas Terrace Apartments, BEFORE Galveston Hurricane
Lucas Terrace Apartments,
AFTER Hurricane
Wind Tides
Pamlico & Albemarle
sounds, NC
Westerlies Blow Water Down
Estuaries
Wind -Creates Most Ocean Waves
Wave Height is Controlled by 1. Wind Velocity 2. Fetch = Distance Water Surface is Subjected to Wind
Wind Waves
Waves = Movement of Motion
Wind Waves
SurfSurfSwashSwash
Wave BaseWave Base
SurfSurf
SwashSwash
•• Wave BaseWave Base
Breaking Wave in Shallow Water
Beach TermsSwashSwash SurfSurf BreakersBreakers
BermBermOld Old BermBerm
Wave Erosion-Deposition
• Wash-Over• Refraction• Longshore Current• Londshore Drift
Beach Erosion in the USA
Hurricane Fran 1996
North Carolina Beach before Hurricane Fran, 1996
See Changes in Next Slide
North Carolina Beach after Hurricane Fran, 1996
Wash-Over DepositsSee Changes from Last Slide
Hurricane Fran Damage from Wash-Over
Beach Erosion:
ThirdCape Hatteras Lighthouse,
North Carolina
Now Relocated in Fourth
Different Site
Stopped Here 10 March 2009
Wave Refraction
Wave Refraction
Longshore Current & Longshore Drift
Longshore Current & Longshore Drift
LSCLSC
LSD
Coastal Structures
• Groins
Coastal Structures: Groins, Ocean City, NJ
Plummer et al., 2005, 10th ed., p. 347Ocean City NJ
USGS Air Photo from
Terraserver.com See also Matthew 7:26
Coastal Structures: New Jersey JettiesPlummer et al., 2005,
10th ed., p. 347
Spit: South Carolina Barrier Islands
HistoricalChanges
in aVirginia Barrier Island
Presque Isle, Lake Erie, PA,image courtesy Chris Schaney
LSD
Baymouth Bar
Primary v. Secondary Coasts (Both Examples from California)
Primary Shoreline, Pensacola Florida
Secondary Shoreline, Northern California
Sandy Primary
Shoreline: AlbemarleSound, NC
“Drowned”Roanoke
River Valley
Rocky Shoreline: Nova Scotia
Primary, relict from Glaciation
Headland ErosionWave Energy Concentrated on Headlands, Dispersed in Bays
Wave-Cut Landforms
Wave-Cut Beach, California
Wave-Cut Shoreline, California
Idiotic Building
Oregon CoastPhoto by J.S. Kite
High-Energy Rocky Shoreline: HeadlandHunter's Brook Beach, Acadia National Park Maine
http://www.acadia.net/anp/10oceand.jpghttp://www.acadia.net/anp/10oceand.jpg© 1997 AcadiaNet Inc., Producers of The Downeast Guide
A Tombolo in California
Reefs Fringing Volcano
Atoll
Eroding Volcanoes with Fringing Reefs
Atoll
Coastal Landforms
MarineTerraces
Wave-Cut Cliff
MarineTerrace
Active Seastacks
Paleo-Seastack
Wave-Cut Bench