pure geog coasts notes!

coasts gateway1 factorsaffectingwaveenergy: - windspeed;fasterwind,greaterwaveenergy- windduration;longerwindblows,largerwaves- fetch;greaterfetch,greaterwaveenergy howwavesaffectcoastalareas: - swash;whenwavesbreakonacoast,carriessedimentswithit(breakscosoffrictionandgravitywithland)- backwash;carriessedimentsfromcoasttosea - constructivewaves;breakfarfromshorewithlittleenergy.depositssediments,notalotoferosion,, andformsgentleslopes(strongswash,weakbackwash)- destructivewaves:breaksviolentlyontheshorewithhighenergy.removessediments(erodefinersediments)andleavesonlycoarsesediments,causingsteepgradient.(weakswash,strongbackwash) + theircharacteristics- constructivewaves:lowgradient,smallwavesandlowwaveheight,longwavelength,6-8permin,swashmorepowerfulthanbackwash- destructivewaves:steepgradient,largewavesandwaveheight,shortwavelength,10-14permin,backwashmorepowerfulthanswash waverefraction: 1. wavesapproachheadlands,divergetobays.2. sincemorewaveenergyatheadlands,moreerosionoccur,splitstobaysbutlessererosion coastalprocesses: - erosion- hydraulicaction=wavesstrikecliff,trapsairinrockjointsandcompressed,puttingpressureonthejoints.jointsweakenedandeventuallyshatters

- abrasion=wavesbreakatcliff,sedimentsmeanttobedepositedarehurledagainstthecoast,scrapesandloosencliffs.eventuallyundercutsthecliff- attrition=rockparticlescarriedbywavesbreakdownintosmallerpiecesandbecomesmootherandmoreroundedovertime(class5!)- solution=seawaterchemicalrxnwithwater-solmineralsincoastalrocks.rocksareweakenedandeventuallydisintegrate sedimentmovement/transport: - beachdrift=sedimentsmoveupthebeachatanangleasswashandperpendiculardownthebeachasbackwash(zig-zagmovement)- longshoredrift=longshorecurrents(currentsthatflowparalleltoacoast)generated,movingsedimentsalongtheshore.- longshorecurrents+beachdrift=longshoredrift sedimentdeposition: - sedimentserodedfromcoastsaretransportedawayanddepositedelsewhere.aswaveenergydecreased,wavesareunabletocarrysedimentsanddepositslargesediments→smallsediments,resultinginavarietyofbeaches- locationofcoasts:- coastsshelteredfromstrongwinds=lessdestructivewaves- deepbaysshelteredbyheadlands=sandybeaches cliffs - hydraulicaction/abrasionerodescrack/jointontherocksurface,enlargingtoformanotch- furtherdeepenedtobecomeacave- moreerosion=roofofthecavecollapses,formingasteepcliff headlands+bays(johor,msia) - lessresistantrocks=bayerodedfasterthan- moreresistantrocks=headlands

caves→arch→stack - partsofheadlandswithlessresistantrockcanbeeasilyeroded(hydraulicactionandabrasion),formsacave- cavesmaydeveloponbothsidesoftheheadland,andfurthererosionmayeventuallyjoincavestgtandcreatinganarch(bridgeofrock)- furtheron,theroofofthearchcancollapsetoformastack beaches - azoneofsedimentdeposition;loosesand,gravel,pebbles,brokenshells,corals- usuallycomefromerodedcliffs,riverdepositsandsedimentscarriedbywaves. spitsandtombolos - spit:along,narrowridgeofsedimentswithoneendattachedtoamainland,formedbylongshoredrift.- whenthereisanabruptbendinthecoastline,longs