Wave Erosion and Marine Geology : Wave Erosion and Marine Geology


Wave Motions: Wave Motions Particles in a wave travel circular paths The water in a deep-water wave does not move forward Below wave base, wave effects are negligible


The Highest Recorded Ocean Wave: The Highest Recorded Ocean Wave


When Waves Meet the Shore: When Waves Meet the Shore When the bottom interferes with wave motion, the wave steepens and the top overtakes the bottom.


Wave Refraction: Wave Refraction Waves change path when they reach shallow water Wave energy is concentrated on headlands and spread out in bays


Rips: Rips When waves break parallel to a beach, rips occur


Storm Waves: Galveston, Texas, September 8, 1900:: Storm Waves: Galveston, Texas, September 8, 1900: 6000-8000 dead 3600 houses destroyed


Raising Galveston – 6 in. to 17 ft.: Raising Galveston – 6 in. to 17 ft.


“A rickety maze such as Dr. Seuss might have drawn”: “A rickety maze such as Dr. Seuss might have drawn”


The Lift in Progress: The Lift in Progress


Pumping in the Sand: Pumping in the Sand


The Galveston Seawall: The Galveston Seawall


In the long run, nothing is as futile as trying to resist shoreline change.: In the long run, nothing is as futile as trying to resist shoreline change. Change can be resisted for a while, but when the water wants something badly enough, it will come in and take it.


Property Values and Shoreline Erosion: Property Values and Shoreline Erosion If more than half the original lot is left, it’s Location, Location, Location After that, it becomes obvious there soon won’t be any location left


Freak Waves : Freak Waves Addition of waves of different frequencies Theoretically could reach 200 feet in Gulf of Alaska One nearly sank the Queen Mary in WWII, with 15,000 troops aboard.


Marine Erosion: Marine Erosion Chemical Attack Abrasion Wave Impact Compressed Air Backwash


Longshore and Beach Drift: Longshore and Beach Drift Most Beach Sand Is Created by Weathering and Carried to Coasts by Rivers Beach Sand Moves along the Coast by Longshore and Beach Drift


Types of Coast: Types of Coast Degree of Modification Primary - Not Modified Much by Wave Action Secondary - Highly Modified by Wave Action History Emergent - Land Rises or Water Level Falls Submergent - Land Sinks or Water Level Rises Dominant Process Erosional Depositional


Effects of the Pleistocene: Effects of the Pleistocene Sea level has risen at least 100 meters in the last 18,000 years Most coastlines globally are submergent Primary coastlines are very common


Secondary Coasts Are Modified by Marine Erosion or Deposition : Secondary Coasts Are Modified by Marine Erosion or Deposition


Secondary Coasts: Secondary Coasts Erosion Stack Terraces Tombolo Erosion rate becomes very slow wave energy dissipated crossing the wave-cut terrace. Cliffs become higher, meaning more material to move. Deposition Spit Lagoon Baymouth Bar Barrier Bar


Primary Coastlines Are Very Common : Primary Coastlines Are Very Common Drowned River Valleys (Estuaries) Drowned Glacial Valleys (Fiords)


Other Ways Primary Coasts Can Form: Other Ways Primary Coasts Can Form Deltas Volcanic Activity Uplift


Primary and Secondary Coastlines: Primary and Secondary Coastlines


Delta Coasts: Delta Coasts Deposition-Dominated Wave Dominated Tide-Dominated


The Mississippi – A Deposition-Dominated Delta: The Mississippi – A Deposition-Dominated Delta


Yukon and Nile Deltas – Balance of Deposition and Wave Action: Yukon and Nile Deltas – Balance of Deposition and Wave Action


Sao Francisco, Brazil – A Wave-Dominated Delta: Sao Francisco, Brazil – A Wave-Dominated Delta


Ganges, Bangladesh – A Tide-Dominated Delta: Ganges, Bangladesh – A Tide-Dominated Delta


Reefs Are a Major Type of Coast in Tropical Areas : Reefs Are a Major Type of Coast in Tropical Areas


Tarawa – A Typical Atoll: Tarawa – A Typical Atoll


Reefs Also Form along the Edges of Large Islands and Continents: Reefs Also Form along the Edges of Large Islands and Continents These Are Barrier Reefs Australia Yucatan Belize West Florida


Turbidity Flows – Grand Banks, 1929 : Turbidity Flows – Grand Banks, 1929