Shoreline Processes
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The document discusses various shoreline processes driven by wave motion. It explains that waves form as energy moves through water, with water particles moving in a circular pattern. As waves approach shallow water, they break due to friction, piling up water that rushes onto the shore and moves sediment. Waves typically approach the shore at an angle and carry sediment along the coast in a zig-zag pattern through longshore transport. Breaking waves can also transport sediment diagonally inland during swash before the sediment moves seaward during backwash.
Shoreline Processes
- 1. Photo by W. W. Little Shoreline Processes
- 2. Wave Motion Waves are formed as energy moves through water. Water particles move in a circular pattern, more or less returning their point of origin once the wave has passed.
- 3. Photo by W. W. Little
- 4. Breaking Waves As waves approach shallow water, they hit bottom. Due to the resulting friction, the upper part of the wave moves more rapidly than the lower part. Water piles up and the wave breaks, causing water to rush onto the shore. Sediment is moved both by wave base and by surf.
- 5. Photo by W. W. Little
- 6. Longshore Transport Waves typically approach the shore at an angle. Upon breaking, their momentum carries sediment onto the beach in the direction of the angle of encroachment until wave energy is spent. Gravity then pulls the wave and sediment seaward, perpendicular to the shoreline. This process carries sediment along the coast in a zig- zag pattern.
- 7. Photo by W. W. Little Surf/Swash Breaking waves (surf) are capable of transporting large volumes of sediment diagonally landward as part of the beach swash.
- 8. Photo by W. W. Little Swash (breaking wave) Backwash (return flow) Backwash Once wave energy has been expended as swash, water and sediment move seaward, perpendicular to the shoreline, as backwash.
- 9. Photo by W. W. Little
- 10. Photo by W. W. Little
- 12. Beach Progradation Beach progradation is a type of lateral accretion, as beach ridges build basinward through long-shore transport.
- 14. Channels Numerous small fluvial channels flow to the swash zone.
- 15. Rip Currents Water piled against a shoreline by ocean currents must return to sea. It does so by flowing as a stream through breaking waves.
- 18. Cause of Tides Passage of the Moon overhead creates a gravitational bulge that migrates with the Moon’s orbit. An equal bulge is formed concurrently on the opposite side of the earth.
- 22. Transgressive vs. Regressive Shorelines The types of depositional systems that dominate a shoreline differ depending upon whether base-level is rising or falling.