Introduction to Coastal Introduction to Coastal ProcessProcess

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?

Straight CoastlinesStraight Coastlines

MadagasgarMadagasgar IndonesiaIndonesia

Some basic relationshipsSome basic relationships

Headlands & Headlands & promontories= resistant promontories= 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

Gulf Coast and Gulf Coast and Eastern SeaboardEastern Seaboard

NASA

ECB.org

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.