Presentation on theme: "— Robert Browning Hamilton (Brainyquote.com)"— Presentation transcript:
1— Robert Browning Hamilton (Brainyquote.com) 20Coastal Processesand Terrain“The sea heaves up, hangs loaded o'er the land, Breaks there, and buries its tumultuous strength. ”— Robert Browning Hamilton (Brainyquote.com)
2Coastal Processes and Terrain The Impact of Waves and Currents on the LandscapeCoastal ProcessesCoastal Landforms
3The Impact of Waves and Currents on the Landscape Coastal ProcessesErosion – by waves, mainlyDeposition – by currents, mainlyRocky cliffs and headlandsMain erosional featuresBeaches and sandbarsMain depositional features
4Coastal Processes Erosion and Deposition Coast Involves the transfer of energy from the atmosphere (wind) to the hydrosphere (ocean) and then to the lithosphere (land).Kinetic energy transferWindDepositionErosionWindCoast
5WavesWave Motion and Wave RefractionTsunamiAnimationDefinition – A disturbance in water caused by energy passing through it.Wave terms: wavelength, wave crest and trough, swashFig. 20-2
6Wave Refraction (see previous animation) Fig. 20-5
7Formation of ArchesFig Headland erosion in Australia along the southern coast of the state of Victoria, read caption, pg 592.
8Wave Erosion, see caption, pg 593 Hydraulic pounding and sea cliff erosionChemical action (some rocks are soluble in sea water)Fig Formation of a Wave-Cut Notch
9Wave Erosion Cliff face Former shore Notch Wave-cut platform Sea Level Fig Formation of a Wave-Cut Notch
10Tides Animation (Tides) Significant erosion agents in narrow bays, margins of shallow seas, and straits.Fig Bay of Fundy has the highest tidal range in the world. Tidal action created these pedestal rocks on the edge of the bay, read caption, pg 595.
11Changes in Sea Level and Lake Level Due to:Tectonic uplift or sinking of landmassEustatic – increase or decrease in the volume of water in the oceans (Pleistocene glaciations). Also, global warming.Fig Northern California coast is experiencing tectonic uplift.
12Currents and Coastal Sediment Transport Longshore Currents (see next slide and stabilization animation)Wave refractionBeach DriftingParticle-by-particle transport of beach materialFigure 20-12
13Fig. 20-13. Waves approaching the shore obliquely causes longshore currents and beach drifting.
14Coastal Deposition Based on the sediment budget of a shore Deposition mainly occurs when inputs from longshore current and wave action exceeds outputs from storm wave action.E.g. large beaches and sand dunesFigFig One of the largest coastal dune accumulations is on the Oregon coast.
15Coastal Landforms Depositional Landforms Beaches Most widespread marine dispositional feature on land (mostly sand deposits)Fig Components of the beach environment
16Spit and related features Spit: Linear strand of marine sediments attached to shoreFormation usually involves longshore current transportRelated featuresFig Types of spits and the longshore current.
17Bay (3) Baymouth bar (2) Hook Land Simple spit Ocean Idealized drawings of formation of spit and related featuresBay(3) Baymouth bar(2) HookSimple spitLandOcean
18Photographs of spits and related features Fig Spit at Cape Henlopen, Delaware
19Small island / sea stack Tombolo formationLandOceanSmall island / sea stack
20Fig. 20-18. Tombolo and Mont Saint Michel on the northwest coast of France.
21Barrier Islands (also, Fig 20-20, pg 602) Coastal islands, parallel to the mainland shoreComplex originsPleistocene sediments washed toward mainland or longshore transport and spit segmentationLagoon formationLandward side of barrier island, protected from large wavesLow energy environment, fine mud deposits (tidal flats)Fig
22Human Alteration of Coastal Sediment Budgets Beach starvation (unintentionally shrinking beaches)Dam construction on rivers reduces sediment discharge into oceans, starving nearby beaches of sandOld debris dam in Santa Ynez Mountains, near Santa Barbara, CA (Richard A. Crooker photo)
23Beach nourishment (re-building beaches) Adding sand to beaches by dredging and pumping sand from off-shoreA slurry of sand and water is pumped on shore and the sand is spread onto the beach of Rehoboth Beach, DE (Richard A. Crooker photos) (overlay)
24Animation (Coastal Stabilization Structures) Beach preservation (maintaining beaches)Build structures that modify longshore transport and wave action in order to keep sand on beachesJetties and groins (see personal pictures)Fig
25Shorelines of Submergence Ria Shorelines (formed at the end of the last ice age)Hilly or mountainous areasflooded valleys become estuaries (long fingers of seawater projecting inland). Dams also create similar landforms, although these are technically not estuaries (see photos of Hoover Dam).Fig , Chesapeake Bay. Read caption, pg 603.
26Fjorded CoastsFjord – glacial trough that is cut so deep that it is inundated by the sea (after glacial melting)Fig
27Shorelines of Emergence Wave-Cut Cliffs and Platforms (photo, pg 604)Marine Terraces are uplifted landforms (captions, pg 605)- Fig and 27.Near Fort Ross, CA
28Coral Coasts Coral Polyps Reef-building creatures, in warm tropical watersFig