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IntroductionIntroduction
½ world’s ½ world’s population in population in coastal regionscoastal regions
Coastal Coastal modification modification impacts humans impacts humans and other and other organisms/plantsorganisms/plants
Present-day Present-day climate change climate change will modify coastswill modify coasts
LA Times
Class FocusClass Focus
Shaping of CoastlineShaping of Coastline Processes operating on coastlineProcesses operating on coastline Changes along the coastChanges along the coast
More Specific Class FocusMore Specific Class Focus
Geology influence on coastal featuresGeology influence on coastal features Nearshore processesNearshore processes Fluvial processesFluvial processes Sea level and climateSea level and climate Sediment transportSediment transport
Some TerminologySome Terminology
ShoreShore Zone between low Zone between low
tide level & upper tide level & upper level of wave level of wave action. In our action. In our coasts, usually cliffscoasts, usually cliffs
Consists of Consists of foreshore, foreshore, backshore, and backshore, and nearshorenearshore
TerminologyTerminology ShorelineShoreline
Water’s edgeWater’s edge BeachBeach
Loose sediment (sand, gravel, Loose sediment (sand, gravel, boulders) accumulationboulders) accumulation
Mostly in backshoreMostly in backshore CoastCoast
Includes shores & nearshore to Includes shores & nearshore to where waves breakwhere waves break
Inland to where marine influences Inland to where marine influences cease—cliffs, lagoons etccease—cliffs, lagoons etc
Will vary in widthWill vary in width Where air, sea, water mixWhere air, sea, water mix Influenced byInfluenced by
Tectonics and lithologyTectonics and lithology Oceanographic processes—waves, Oceanographic processes—waves,
tides, currenttides, current Sea levelSea level Atmospheric processes—wind, Atmospheric processes—wind,
precipitationprecipitation Coasts shaped byCoasts shaped by
ErosionErosion DepositionDeposition
Ancient CoastlinesAncient Coastlines
Sedimentary geologistsSedimentary geologists Reconstruct sedimentary Reconstruct sedimentary
environmentsenvironments Ancient shorelines Ancient shorelines
preserved throughout preserved throughout rock recordrock record
Help reconstruct ancient Help reconstruct ancient sea level rise and fallsea level rise and fall Global record vs local Global record vs local
recordrecord Climate vs tectonic Climate vs tectonic
activityactivity
Oysters, Vaqueros Fm.
Picasaweb.com
Shape of coastlinesShape of coastlines
Straight or Straight or curvedcurved E.g. san E.g. san
Andreas Fault Andreas Fault in San in San Francisco areaFrancisco area
Madura, Madura, IndonesiaIndonesia
East East MadagascarMadagascar
Based on U.S. Geological Survey map
TerminologyTerminology CoastlineCoastline
Land margin at Land margin at normal high tidenormal high tide
Difference Difference between between coastline and coastline and shoreline?shoreline?
Some basic relationshipsSome basic relationships
Headlands & Headlands & promitories= resistant promitories= resistant rocksrocks
Bays = less resistant rock Bays = less resistant rock or tectonic folding, tiltingor tectonic folding, tilting
Embayed coastline with Embayed coastline with valley mouth usually valley mouth usually submergedsubmerged E.g. east U.S. coastE.g. east U.S. coast
Gulf coast formed by Gulf coast formed by deposition = curved coastdeposition = curved coast
Marin Headlands, San Francisco area Photo (c) Andrew Alden
Rounded BaysRounded Bays
Submerged Submerged volcanoesvolcanoes
E.g. SantoriniE.g. Santorini Hanauma Bay, Hanauma Bay,
OahuOahu Hanauma Bay and Koko Crater at Koko Head, Oahu
NASA
Evolution of Coasts
Tectonic ProcessesTectonic Processes Separation of platesSeparation of plates Active tectonic Active tectonic
processes—faulting processes—faulting and foldingand folding
Climate—wind, rain, Climate—wind, rain, weathering & weathering & decomposition, decomposition, vegetationvegetation
Rising and falling tidesRising and falling tides
Changing CoastlineChanging Coastline
AdvancingAdvancing Sedimentation Sedimentation
is greater than is greater than erosionerosion
Emergence, Emergence, uplift, sea uplift, sea level falllevel fall
RetreatingRetreating Erosion Erosion
greater than greater than depositiondeposition
Sea level riseSea level rise subsidencesubsidence
Rates of Coastline ChangeRates of Coastline Change
RapidRapid StormsStorms Lava flowsLava flows EarthquakesEarthquakes
GradualGradual Longer termed changesLonger termed changes Tectonic uplift, sea level riseTectonic uplift, sea level rise
Measure changing coastlineMeasure changing coastline Maps, photographs, gps, etc.Maps, photographs, gps, etc.