Accessing Reading Material on Library ReserveReading MaterialPreparation for Mid-Term Exam next Wednesday, 25 OctoberPuget Sound CruiseObservations during cruisePuget Sound MorphologyBathymetry (water depth)Hydrography (water properties)Types of river-mouth environments Puget Sound SedimentationMechanisms associated with SedimentationAccessing Reading Material on Library ReserveWebsite: www.lib.washington.eduOptions on left: “Course Reserves”Search by Course: “Oceanography 230”Search by Professor: “Nittrouer”“List of electronic materials for Oceanography 230”“Connect to this title on line; UW restricted”Enter UW net infoAccept copyright agreementReading MaterialOn reserve in:Undergrad Library: hard copiesUW Library website: www.lib.washington.edu“Ocean Basins”, from “Oceanography”M.G. Gross, Prentice-Hall“River Deltas”, from “The Coast of Puget Sound”J.P. Downing, Puget Sound BooksPreparation for Mid-Term Examnext Wednesday, 25 OctoberReview class lectureshttp://gis.ess.washington.edu/grg/courses05_06/ess230/Reading material www.lib.washington.eduOld exam questionswill distribute on FridayField Trip BWorking cruise in Puget Sound on the Thompson, UW’s oceanographic research vesselWednesdayOctober 18 start 7AMAll day(no class)end ~9PMPuget Sound CruiseTime: Depart UW 7AM Johnson Hall Parking LotReturn UW 9 PM Johnson Hall Parking LotClothing: foul-weather gear, hat, fleece, good shoesPrepare for cold, wet, windy and muddy conditionsFood: Lunch and dinner onboard shipSpecial dietary needs?Observations during cruiseWater columnCTD = chlorinity, temperature, depthturbidity (suspended sediment)SeabedGrab samples – surface sedimentbox core – 50-cm-long piece of seafloorkasten core – 250-cm-long record of sedimentationSeafloor mappingmultibeam acoustic profilesBelow seafloorseismic profilesPuget Sound MorphologyGlacial Originscour – flow under ice sheetformed depressionse.g., Main Basin, Hood Canal, Lake Washingtonsedimentary deposits – also raised land surfaceglacial tills, outwash deposits, lake depositsold glacial sediment now provides new input to PScliff erosionlandslidesland surface erosionBathymetry (water depth)Shallow entranceglacial origin – moraineoceanographic name – sillprimary sill is Admiralty InletSeveral others divide PS into separate basins (>200 m)Main Basin has 46% of water volumeSinuous shape – result of originSouthern Basin has 29% of shorelinesFluvial (river) sediment supplyfills PS from shorelineWhidbey Basin has 43% of tidelandsHydrography (water properties)Salinity (amount of salt dissolved in water)river water has 0 ppt (parts per thousand)ocean water has ~35 ppt – differs around worldbrackish water at depth in PS – 20-30 pptDensity (low salinity = low density)river plume flows over more dense brackish waterInput of river water - varies with space and timenorthern PS rivers supply the most watersmall input during late summerlarge input during late autumn and winter rainslarge input during spring snowmeltTypes of river-mouth environmentsestuary – semi-enclosed settingriver and salt water meet and mixfjord – estuary with glacial origindeep, with shallow sill near mouthdelta – river mouth receiving much sedimentestuary filled with sedimentshoreline growing seawardPuget Sound SedimentationSources of sedimentshallow – shoreline erosion, landslidesdeep – biological productivity, algal debrismuch carbon decomposes,forming methane gasall depths – river dischargedeltas form near river mouthsriver plume carries sediment deepernear sill – inflow with deep ocean waterMechanisms associated with Sedimentationplume transport – turbid surface waterriver momentum, tides, windflocculation – silt and clay particles form larger aggregates, which sink quicklylandward bottom flow – traps sediment near riverdelta formation – thick deposits near river mouthtopset = tidelandsforeset = steep surface, rapid accumulationbottomset = deep deposits, escape seawardDuwamish deltaIntensely impacted by humansWetlands hardened (landfill, roads, parking lots, buildings)Distributarychannels altered and stabilizeddepth in mDuwamish delta4-m resolution, 5x VENisqually deltanearly natural conditionSeveral distributarychannels bring water and sediment across delta to Puget SoundNisqually Delta, 5x VE3-m resolution, looking SWdepth
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