Chapt 20-Coastal Processes and Terrain

Chapt 20-Coastal Processes and Terrain - Chapter 20:...

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Chapter 20: Coastal Processes and Terrain I. The Impact of Waves and Currents on the Landscape A. erosion 1. waves are agents of erosion 2. most notable wave-created land features: headlands and rocky cliffs B. deposition 1. currents are agents of deposition 2. land features: beaches and sandbars II. Coastal Processes A. Intro 1. coastline is interface between 3 major components of Earth's environment: hydrosphere, lithosphere and atmosphere 2. large bodies of water can be deformed by wind action waves and ocean currents affect topography along coastlines 3. larger the body of water, the greater the effect of coastal processes B. Waves 1. waves : rising and falling motions transmitted from particle to particle in a substance, carrying energy from one place to another in the process 2. most water waves are wind generated a. set in motion by friction of air blowing across water b. transfer of energy from wind to water initiates wave motion 3. waves of oscillation : cause circular movement of water particles with very little forward motion a. wave crest : produced when water moves upward b. wave trough : produced by sinking of water surface c. wavelength : distance from crest to crest d. wave height : vertical distance from crest to trough; depends on 1) wind speed 2) wind duration 3) water depth 4) fetch: area of open water e. wave amplitude : one-half wave height
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f. passage of wave of oscillation moves water only slightly in direction of flow : object floating on surface bobs up and down 4. waves of translation : waves formed in shallow water by frictional drag on the sea bottom; result in horizontal movement of surface water a. waves break when they reach shallow water and the sea bottom causes their height to increase and their slope to steepen b. ocean bottom impedes oscillation, causing the wave to become oversteepened until it collapses c. swash : cascading forward motion of a breaking wave that rushes up on a beach d. backwash : water moving seaward after the momentum of the wave swash is overcome by gravity and friction 5. wave refraction : phenomenon whereby waves change their directional trend as they approach a shoreline a. causes: uneven coastline or irregularities in water depth b. geomorphic result: wave action focused on headland smoothing of coastal outline 6. tsunamis / seismic sea waves : very long sea wave generated by submarine earthquake or volcanic eruption a. can travel several hundred mph b. build to considerable height when approach shore 7. water waves normally pass harmlessly under objects in open water but can wreak devastation along a shoreline a. wave of oscillation: generally gentle b. wave of translation: can be a powerful destructive force C. Changes in Water Level 1. tectonic sea level changes: result from uplift/sinking of a landmass 2. eustatic sea level changes : result from increase/decrease in the amount of water in the oceans
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Chapt 20-Coastal Processes and Terrain - Chapter 20:...

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