Igneous Rocks and VolcanoesView From Space - Klyuchevskaya, RussiaCleveland Volcano, AlaskaMount Etna From SpaceSlide 5Slide 6Mount EtnaShiveluch, RussiaMagma – molten rock beneath the surface Lava – molten rock on the surfaceIgneous Rocks Cool from the Molten StateIgneous Rock ClassificationFeldsparsBowen's Reaction SeriesSlide 14Bowen's Series and Igneous RocksSlide 16Bowen's Series and VolcanoesBasalt and AndesiteSome Igneous Rocks Are Named on Textural CriteriaTypes of VolcanoesA Cinder Cone: Wizard Island, Crater Lake, OregonAnatomy of a Cinder Cone, HawaiiTuff Ring: Diamond Head, HawaiiSlide 24Shield Volcano: Haleakala, HawaiiStratovolcano: Mount Shasta, CaliforniaShastina and Landslide DepositLava Dome, CaliforniaProducts of EruptionsEnvironmental Hazards of VolcanoesPyroclastic Flow or Nuee Ardente (French: Fiery Cloud)How Calderas FormCrater Lake, OregonJemez Caldera, New MexicoCollapsing Volcanoes – Mount RainierCollapsing Volcanoes - HawaiiEvolution of VolcanoesSlide 38Igneous Rocks and VolcanoesView From Space - Klyuchevskaya, RussiaCleveland Volcano, AlaskaMount Etna From SpaceMount Etna From SpaceMount Etna From SpaceMount EtnaShiveluch, RussiaMagma – molten rock beneath the surfaceLava – molten rock on the surfaceIgneous Rocks Cool from the Molten State•Volcanic -- Erupted on Surface •Plutonic -- Solidify Within Earth Large Grain Size ---> Slow Cooling•Volcanic Rocks -- Fine Grained •Plutonic Rocks -- Coarse Grained Porphyritic Texture:Large Crystals in Fine-grained SettingIgneous Rock ClassificationHow Much Silica? (account for Si)•Excess - Rock Has Quartz •Just Enough to Form Other Silicates •Deficient - Silica-Poor Minerals (Like Olivine)What Feldspars? (Account for Al, Ca, K, Na )•Potash Feldspar KAlSi3O8 •Plagioclase SeriesNaAlSi3O8......CaAl2Si2O8What Other Minerals Are Present? (Account for Fe, Mg)FeldsparsK - Feldspar: KAlSi3O8•Several Slightly Different Forms: •Microcline •OrthoclasePlagioclase (Solid Solution)•Albite: NaAlSi3O8•Anorthite: CaAl2Si2O8•Any Mixture of the Two Is PossibleBowen's Reaction Series•The geologist N.L. Bowen found that minerals tend to form in specific sequences in igneous rocks•These sequences could be assembled into a composite sequence.Bowen's Reaction SeriesNo igneous rock ever displays the whole sequence, just a slice across the sequence.Bowen's Series and Igneous RocksBowen's Series and Igneous RocksVolcanic Rocks(Rare) Basalt Andesite Rhyolite Plutonic RocksDunite Gabbro Diorite Granite1200 C Melting Point 700 CMg, Fe Rich In... Si, Na, KRapid Weathering Slow Usually Dark Color Often LightBowen's Series and VolcanoesVolcanic Rocks(Rare) Basalt Andesite RhyolitePlutonic RocksDunite Gabbro Diorite GraniteFluid Lava Is... ViscousMild Eruptions ViolentType of VolcanoShield Volcano Stratovolcano Plug DomeBasalt and Andesite•Hard to tell apart by eye•Distinction is mostly chemical•Why it Matters:–Basalt = Planetary Raw Material–Andesite = Basalt reacting with silica rich crustSome Igneous Rocks Are Named on Textural Criteria•Pumice - Porous•Obsidian - Glass•Tuff - Cemented Ash •Breccia - Cemented Fragments •Porphyry - Fine Matrix, Large CrystalsTypes of VolcanoesA Cinder Cone:Wizard Island, Crater Lake, OregonAnatomy of a Cinder Cone, HawaiiTuff Ring: Diamond Head, HawaiiTuff Ring: Diamond Head, HawaiiShield Volcano: Haleakala, HawaiiStratovolcano: Mount Shasta, CaliforniaShastina and Landslide DepositLava Dome, CaliforniaProducts of EruptionsLava Flows Pyroclastic Debris •Bombs •Lapilli •Ash MudflowsLandslidesGases •Steam •Carbon Dioxide •H2S •SO2 •HCl •HFEnvironmental Hazards of Volcanoes Pollution •SO2, HCl in Water Lava Flows Falling Ejecta Ash Falls •Building Collapse •Crop Destruction Mudflows •Direct Damage (Colombia, 1985) •Floods (Several Types)Blast (Mt. St. Helens, 1980) Pyroclastic Flow (St. Pierre, 1902) Gas (Lake Nyos, Cameroon, 1986)Pyroclastic Flow or Nuee Ardente (French: Fiery Cloud)How Calderas FormCrater Lake, OregonJemez Caldera, New MexicoCollapsing Volcanoes – Mount RainierCollapsing Volcanoes - HawaiiEvolution of VolcanoesAn active volcanic landscapeEvolution of VolcanoesA volcanic landscape after a million years or