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Geog 106 2/18/2013 Agenda Todaywewilldiscuss 2.GeologicHistory WhatPhysicalGeographyis BriefgeologichistoryofCalifornia Geography106– CaliforniaGeography|M.Pesses|AntelopeValleyCollege PhysicalGeographers Interestedinnatural places &themobility ofmatter&energy SynthesisofEarth’s y history&future Uniformitarianism Thesameprocessesactive todayhavebeenoccurring throughoutgeologictime Invisibletous,but unbelievablypowerful Instructor: M. Pesses IntrotoCalif.PhysicalGeography NaturaldisastersleadtoCalifornia’sbeauty TheoryofPlateTectonics TheEarth’scrustisbrokenupintoaseriesof “plates” ThesecrustalplatesfloatontopoftheAesthenosphere intheUpperMantle Convectioncell Convection cell 1 Geog 106 2/18/2013 “UnifyingTheory” Tiestogetherearthquakes, volcanoes,mountainranges, pastclimates&fossil evidence PlateBoundaries Diverging Converging Sliding(Transform) Diverging Platespulledapart Seafloorspreading Instructor: M. Pesses 2 Geog 106 2/18/2013 Converging Platescollide Subductionzones Terranes Crustalrockthatcame fromanotherlocation duetothemovement ofplates Sliding(Transform) Whereplatesslide pasteachother Nodiverging,no converging Usuallynovolcanic activity Instructor: M. Pesses 3 Geog 106 2/18/2013 ContinentalMargin CaliforniaisNew Rocks Minerals Minerals Earth’scrust feldspar 8mainelements SiO2 Resilient Minerals Bondedelementswith acrystallinestructure Thebuildingblocksof rocks Instructor: M. Pesses Quartz quartz 4 Geog 106 2/18/2013 Rocks Anassemblageofminerals Granite Quartz,feldspar,mica, hornblende Rocks Categories Exceptions Allrockscanbesortedintooneofthree categories Undifferentiated material Organicmaterial Igneous Sedimentary Sedimentary Metamorphic Obsidian IgneousProcesses Formswhenmagmaorlava solidifies Magma Moltenrockunderneath surfaceoftheEarth f f th E th Lava Whenmagmareaches surfaceoftheEarth Instructor: M. Pesses 5 Geog 106 2/18/2013 IntrusiveIgneousRocks Termforrockformedbycoolingmagma Magmafillsincracks Slowcooling Largegrainsize IntrusiveIgneousRocks Massofintrusiverockcalledpluton Largeplutoncalledabatholith Intrusiveigneousrocksalsocalledplutonic rocks ExtrusiveIgneousRocks Rocksformedby coolinglava Coolsquickly Finegrained g Alsocalledvolcanic rocks Granite Intrusive Mediumtocoarse grained Felsic Richinfeldsparand silica Instructor: M. Pesses Rhyolite Extrusive Finegrained Felsic Cools too quickly Coolstooquickly Obsidian 6 Geog 106 2/18/2013 Basalt Extrusive Finegrained Mafic SedimentaryRocks Madefromlayeringofbrokendownrock&mineral particles Sometimesorganicmaterial Rich Richinironand in iron and magnesium Makesupmostof oceanfloor TheProcess Weatheringbreaksdownsurfacematerials Water,wind,orglacialicetransportsthese sediments Burialofsedimentsleadstocompaction, l f d l d cementation,&hardening Subclasses 1. Clastic 2. ChemicallyPrecipitated 3. Organic Whichcreatesrocks SedimentaryRocks Examples Clastic Madeoffragmentsofrock&minerals Layering Instructor: M. Pesses 7 Geog 106 2/18/2013 SedimentaryRocks Chemicallyprecipitated Dissolvedmineralsorhardpartsoforganisms Transportedinsolution,thenprecipitated Evaporites Waterevaporates,leavessalt DeathValley,afterrain OrganicSedimentaryRocks Sedimentmadefrom decayinganimal& planttissue DeathValley,afterwaterevaporates Hydrocarbons Solid Coal,Peat Liquid Petroleum Gas Naturalgas Fossils AlmostExclusivelyinSedimentaryRocks HeatofMeltingorMetamorphismWouldDestroy AlmostEveryTypeofFossil BuriedRapidlyAfterDeath,PreservedFromDecay EnvironmentalClues Fossils SaltWater– Corals,Echinoderms FreshWater– Insects,Amphibians Terrestrial– Leaves,LandAnimals , Color&Chemistry RedBeds– OftenTerrestrial BlackShale– OxygenPoor,OftenDeepWater Evaporites– AridClimates Instructor: M. Pesses 8 Geog 106 2/18/2013 MetamporphicProcesses Changesinsedimentaryorigneousrockduetoheat orpressure Radioactivedecay PressuredeepwithinEarth GeologicTime GeologicTime 15billionyears=15,000,000,000years 15billionseconds=475years Considering1secondtocorrespondto1year: BigBang‐ A.D.1526 Earth’ssFormation‐1858 Earth Formation ‐1858 Dinosaurs‐ livedfrom1993‐1999 Humans‐ appeared2weeksago IceAgeswouldhavehappenedeverydayforthelast2weeks. Thelastonewouldhaveended5hoursago JuliusCaesar‐ lived44minutesago UnitedStates– createdjustover3½minutesago WorldWarII‐ ended56secondsago Instructor: M. Pesses 9 Geog 106 2/18/2013 GeologicTime HistorybrokenupintoEons,Eras,& Periods ChangebasedonchangeinEarth’sbiology, atmosphere etc atmosphere,etc. Dating Absolute Relative PrecambrianEon ProterozoicEra (2.5bya– 545mya) Aneraisasubsectionofaneon MostofCaliforniaunderwater EvidenceinDeathValleyofshallowsea PaleozoicEra (542mya– 251mya) MostofCaliforniastill underwater PrecambrianEon 4.6billionyearsago (bya)‐ 545million yearsago(mya) Oldestrocksin Californiajustunder2 billionyearsold PhanerozoicEon (545mya– present) 3eras Paleozoic Mesozoic Cenozoic PaleozoicEra Pangaeastartingtoformatendofera Tectonicallyactive Terranesfromseafloorspreading Islandarcspushedupagainstcontinent I l d h d i t ti t FossilscommontoEastAsia NorthAmericabeginstogrow Instructor: M. Pesses 10 Geog 106 2/18/2013 MesozoicEra (251mya– 66mya) MesozoicEra Continuedterranebuild‐up FranciscanComplex Medleyofexoticrocksthat makeuptheCoastRanges MesozoicEra GraniticPlutons Subductionofoceanplate Meltsrockintofelsicmagma Intrudesintoexistingrock, cools Eventuallyexposedbyuplift &erosion MesozoicEra Mountainbuilding changedcoastline Nevadanorogeny (approx.150mya) Pushedseainto CentralValley Instructor: M. Pesses MesozoicEra KlamathMountains Bothpluton& blueschistaccretion MesozoicEra KeptoceanoutofBasin&Range Wedon’tfindmarinefossils,butdofindterrestrialred sandstone 11 Geog 106 2/18/2013 MesozoicEra Upliftacceleratederosion Exposedgranite filledCentralValley withsediment CenozoicEra Volcanicactivity SubductionVolcanism Subducingplatemakes felsicmagma,violent volcanoes Responsibleforthe Cascades CenozoicEra (66mya– present) Continueduplift&sedimentdepositsinto CentralValley Pushesseawestward P h d CenozoicEra PinnaclesNationalMonument ErodedvolcanothatoriginatedinwesternAntelopeValley SanAndreasmovedrock200milesNorth CenozoicEra ModocPlateau Basin& Range/Mojave Instructor: M. Pesses 12 Geog 106 2/18/2013 CenozoicEra Glaciallakes&inlandseas NextTime ModernVolcanicLandscapes TronaPinnacles Instructor: M. Pesses 13