Under the Boardwalk: Coastal Geomorphology What to look for while you're on the beach during spring break. 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)
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 Bolo 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 Gibraltar
Bay of Fundy- Mongo Tides What is Deadliest Day in U.S. History? San Francisco Quake, 1906 ~ 500 Dead? Hurricane Katrina, 2005 > 1420 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 1862 Casualties in 3 categories: 1) dead; 2) wounded; and 3) missing or captured. Approximate Numbers Union Confederate Total Killed 2,100 1,550 3,650 Wounded 9,550 7,750 17,300 Missing/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 Hurrican Camille L 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 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 Swash Swash Surf Surf Wave Wave Base Base Breaking Wave in Shallow Water Swash Beach Terms Surf Breakers Old Berm Berm
Wave Erosion-Deposition Wash-Over Refraction Longshore Current Londshore Drift Beach Erosion in the USA Hurricane Fran 1996
See Changes in Next Slide North Carolina Beach before Hurricane Fran, 1996 See Changes from Last Slide Wash-Over Deposits North Carolina Beach after Hurricane Fran, 1996 Hurricane Fran Damage from Wash-Over
Beach Erosion: Third Cape Hatteras Lighthouse, North Carolina Now Relocated in Fourth Different Site Stopped Here 13 March 2003 Wave Refraction Wave Refraction
Longshore Current & Longshore Drift Longshore Current & Longshore Drift LSC LSD
Groins Coastal Structures Coastal Structures: Groins, Ocean City, NJ Plummer et al., 2005, 10 th ed., p. 347 Ocean City NJ USGS Air Photo from Terraserver.com See also Matthew 7:26 Coastal Structures: New Jersey Jetties Plummer et al., 2005, 10 th ed., p. 347
Spit: South Carolina Barrier Islands Historical Changes in a Virginia Barrier Island Presque Isle, Lake Erie, PA, image courtesy Chris Schaney Stopped Here on 13 March 2006 LSD
Baymouth Bar Primary v. Secondary Coasts (Both Examples from California) Primary Shoreline, Northern California
Secondary Shoreline, Pensacola Florida Sandy Primary Shoreline: Albemarle Sound, NC Sandy Secondary Shoreline: Outer Banks Drowned Roanoke River Valley Rocky Shoreline: Nova Scotia Primary, relict from Glaciation
Headland Erosion Wave Energy Concentrated on Headlands, Dispersed in Bays Wave-Cut Landforms Wave-Cut Beach, California
Idiotic Building Wave-Cut Shoreline, California Oregon Coast Photo by J.S. Kite High-Energy Rocky Shoreline: Headland, Maine
Reefs Fringing Volcano Atoll Eroding Volcanoes with Fringing Reefs Atoll Paleo- Seastack Marine Terrace = Old Wave-Cut Bench Wave-Cut Cliff Wave-Cut Bench Active Seastacks
Marine Terraces = Old Wave-Cut Benches Landforms