Week of notes for intro to geo
Week of notes for intro to geo 100
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This 14 page Class Notes was uploaded by Aubree Broyles on Monday February 15, 2016. The Class Notes belongs to 100 at Fort Hays State University taught by Kenneth R Neuhauser in Spring 2016. Since its upload, it has received 20 views. For similar materials see Introduction to Geology in Geoscience at Fort Hays State University.
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Date Created: 02/15/16
Intro to Geology Notes GSCI 100 Section B Spring 2016 - Section 1 Intro Presentation Geology = the study of the Earth – a science Why Geology? o Energy sources + raw materials = Examples: cell phone, computer, car o Protecting the environment o Avoiding geologic hazards = Examples: keeping people safe o Economics + Politics o Consumers + Citizens o Sustainability Approaches in Geology o Observational: field & lab Maps: Rock types, distributions, structures Microscopic investigations o Experimental: field and lab Chemical Geophysical Part of Geology o Lithosphere Rocks o Hydrosphere Water o Atmosphere Air/weather o Biosphere Biology – evolution of species o Cryosphere Frozen Majority of Earth’s Elements –Crust of the Earth o Oxygen (46%) - O o Silicon (28%) Si o Aluminum (8%) Al o Iron (6%) Fe No free oxygen comes out of Volcanoes Plate Tectonics Scientific Method o Question o Observation to collect data o Propose Hypotheses = explanations offered for a set of observations o When a hypothesis withstands many tests it is called a theory o A theory that pasts tests all the time is called a law How to learn o Listen o Take notes o Watch o Teach Day 1 of Lecture Notes – Jan. 21st Atoms, Elements, and Minerals Atoms Minerals Rocks Earth Mineral Identification o Luster Metallic or Non-Metallic o Hardness Uses a scale of hardness – depends on how the atoms are bonded together o Streak Usually for metallic minerals – rub samples on a porcelain plate to see the streak o Cleavage What happens when you break a mineral – when you break a mineral, if it has cleavage it busts into chunks of the same shape o Crystal Form (Habit) The shape that they form o Density Can be tested using acid o Color Double refraction – the light that enters a crystal, is split Asbestos – Health hazard or not? o There are different kinds – good and bad o Good = Lighter colored o Bad = The darker asbestos pieces have curlier fibers and get stuck in lungs and cause health issues Mineral o Natural occurring, inorganic solid with a definite chemical composition and thus a definite atomic structure How minerals form o 1. Cooling of magma o 2. Precipitation Chemical or biochemical (ex. how the human body makes teeth, bones, etc.) o 3. In the “solid state” From tectonic rock Atoms o Nucleus Protons = + charge Neutrons = no charge o Electrons = - charge (electromagnetic nature) o Quarks + Quantum Theory – leave that to chemists and physics Why is Magnetite magnetic? o Electrons (the control it) are spinning in the same direction around the nucleus Isotopes --- Stable and Unstable o It is an atom where the nucleus contains a differing number of neutrons o The more neutrons in a nucleus, the more unstable an atom is Ion o An atom that has lost or gained electrons o Positively charged ions (loss of electron) are called cations --- T&F Question o Negatively charged ions (gain of electron) are called anions Inert Gases o Do not easily give up electrons (outer shell filled) = do not readily form solids o Helium o Neon o Argon o Kryptonite Bonding Types o Ionic bonds – electrons exchanged --- 90% of all minerals --- T&F o Covalent Bonds – Electrons shared o Metallic Bonds – electrons move freely between all atoms Good conductors o Bond strength The stronger the bond, the harder the substance – so it uses the hardness scale The other most rings of atoms with bond – its easier for 1 to move than 7 – needs 8 o Covalent Bonding = Diamond bonding o Polymorphs = same composition, different structure Carbon polymorphs = graphite + diamond Multiple Choice Question = an example of a polymorph is carbon polymorph (Graphite & diamond) o Silica-oxygen tetrahedral 4 oxygens surrounding 1 silicon Different combinations produce different structures o Isolated Tetrahedra (eg. Olivine) o Framework Silicates (eg. Quartz & feldspar) All 4 corners are shared with tetrahedrons o An XDR (X-Ray Detractor) is used to find a crystals “DNA” Other Mineral Oddities o Piezoelectricity If you put pressure on both ends of a crystal, it will transfer electricity – turned this into clocks o Pyroelectricity o Fluorescence o Phosphorescence o Triboluminescence o Ferromagnetism o Liquid crystals o Kaopectate Geophagy = the practice of eating clays – elephants and birds do this in nature and eat clays Igneous Rocks To melt rock: o Increase temperature o Decrease pressure o Add water = lowers melting point To Crystalize water (harden) o Do the opposite ^^ Where might this happen? Heat Sources? o Geothermal gradient o Hot mantle plumes (plume of warm rock) When it gets closer to the surface of the earth, it hardens o Radioactive decay Basalt = one of the most common igneous rocks o Created by the partial melting of a rift system Andesite = another very common rock Granite = another very common rock Igneous Rocks o Cooling + solidification of magma o Plutonic magma (intrusive) = cools below surface o Volcanic lava (extrusive) = cools on or above the Earth’s surface Viscosity o Measure of resistance to flow o High V = stiff o Low V = runny 1. Tempurature: High T = Low V 2. Composition: Higher SiO 2 = Higher V o More gas% = Lower V Textures o Glassy = no minerals present o Crystalline = made of mineral crystals o Porphyritic = mix of crystal sizes (2) o Vesicular = gas bubbles = holes where the gas was o Pyroclastic = frags = explosion = tephra o Pegmatitic = very large crystals Rate of Cooling & Texture Terms o Instantly = glassy* o Fast = Aphantitic o Slow = Phanertic* o 2 rates of cooling = Porphyritic* o Explosive = pyroclastic o Very slow-med. = pegmatitic Phenocrysts o When there are 2 cooling rate in rocks, crystals form inside the matrix - Porphyritic Glassy igneous rocks = obsidian, pumice, ash Holes – vesicles (left after the gas is gone) Classification based on: o 1. Compostion Extrusive Extrusive cools faster, smaller crystals Basalt (Mafic) Andesite Rhyolite (felsic) o 2. Texture Intrusive Intrusive cools inside the Earth at a slower rate – bigger crystals Gabbro (mafic) Diorite Granite (felsic) Intruding Magma o 1. Magma invades cracks o 2. Magma melts walls of country rock (in contact with the baked zone – cools first) Xenoith = large chunk of rock that falls or sinks into the magma chamber o 3. Magma breaks off rocks; most slowly melt but a few are preserved Pluton Shapes o Concordant vs. Discordant (which way does it intrude into the rock) Batholith = biggest intrusions – BIG granite mountain when they explode Stock = Sills – layers of magma that squeeze between the layers – not distrupting = (CONCORDANT INTRUSIVE BODY) Dike = cut upwards through the layers – (DISCORDANT INTRUSIVE BODY) Riley county Kansas – great place in KS to find Igneous rock – Eastern KS - Kimberlite Micro-Lite Quarry Silver Dome – Lamproites – Chanute, KS – used as vitamins for cattle Yosemite Batholith – huge granite boulders - plutonic Sangre de Cristo mountains, Spanish mountains – Colorado – intrusive rock Yellowstone – hydrothermal conditions – geysers Hot Spring vs. Geyser o Has to do with plumbing conditions – is it complex or simple o Hot Spring = the hole to where the hot spot is straight and narrow - short o Geyser = more complex system – steam builds up below the ground it chambers – then it ‘burps’ up the geyser Hot water is a source of energy Volcanoes Volcanologists = someone who studies volcanoes Material ejected: o Lava = fluid rock melt that flows on surface of Earth o Tephra = fragments blasted out, solidify in air o Steam (H 0)2= #1 is gas o Carbon dioxide (CO ) 2 o Hydrogen sulfide (H S)2 o No free oxygen gas! Basalt Lavas Aa =rough, blocky, texture (to burn) Pahoehoe = ropy textured surface (to paddle = make swirls) Columnar Basalt o Tephra o “Erupted stuff” o Air-Fall (ash, cinder, Pele’s hair, bombs) Pele’s hair o Pyroclastic flow – dense mixture of super-heated gas, ash+rock Volcanic mudflow (lahar) o Mixture = water + pyroclastic, concrete-like slurry, can move very fast! Other Eruption Styles o Pillow lavas – basalt – it is evidence of submarine (underwater) eruption Phreatic explosion – underwater volcanoes – hot volcanoes mix with the water and makes an explosion – eventually this volcano could become an island Flood basalts Limu O Pele = “skin of pele” = when the waves crash on flowing lava – makes thin layer Volcano Styles Shield o Spread out very wide, until they get above sea level – Hawaii is made of shield volcanoes o Basalt (partial melting of the upper mantle) o Low Viscosity magma o Large Composite o Andesite (medium viscosity) o Mt. Fujiyama, Kilimanjaro o Layers of ash, lava, ash, lava, etc. o Mix pyroclastic + lava flows o Steep slopes o Mt. Rainer, Mt St. Helens Cinder Cones o Ash, cinders + bombs o Not too steep o Some in New Mexico o Relatively quiet Collapsed calderas o Once the magma is blasted away, there’s nothing supporting the top of the volcano so it collapses Other --- Big Ones – Giant volcanoes that blew o Mono Lake, CA Hazards Lava flows Gas Ash Pyroclastic flows Lahars Tsunami (eruption in the ocean that creates a large wave that moves towards the land) Effects on humans Island growth of loss Geothermal energy Catastrophes Effects on climate SRI (Satellite Radar Interferometry) A satellite that goes around the earth and scans an area and sees how the Earth is moving up and down Notes from E-mail – Snowday Chemical weathering is most effective in a warm, humid climate. Frost wedging is a physical weathering example not a chemical one. Water expands (volume increases) when it freezes. - physical weathering Bauxite is a principal ore of aluminum. Pedalfer (aluminum and iron) soils are characteristic of the humid eastern US. Laterite soil form in hot, wet tropoical regions. Humus is the decayed organics (plant and animal) in soil. Chemical weathering is no rapid in a hot desert. Pedocals (calcium rich) soils are common in the western US - more so than eastern US. Quartz is very resistant to chemical weathering. Acid Rain and Acid Mine Drainage Sediments and Sedimentary Rocks Clastics o Compaction Cementation Replacement Chemical Biochemical Precipitation Burial + Compaction o Weight packs grains + fluids move out o Porosity + permeability reduced Cementation / Authigenesis o Precipitates form in pores o Common cements: Quartz Calcite (hematite + pyrite) Precipitation o Directly out of water = halite or gypsum Recrystallization o Some grains disce = solutioning + reprecipitation of minerals Sediment Types o Clastic = weathered particles, solid o Chemical precipitates = ions in solution o Organics = living material [shells, coral, plankton, + plants] bioprecipitates o CaCO [c3lcareous] + SiO [sil2ceous]= most common minerals for cements Porosity vs. Effective Porosity Sorting angularity maturity o How to judge the maturity of a rock based on its shape o Farther down a river, they are closer to the same size What controls settling velocities? (Stoke’s Law) o Grain size, shape, and density The denser objects sink faster Clastic Rocks o Grain sizes + shape: Breccia (angular) Conglomerate (rounded) Arkose (feldspar) Sandstone (quartz) Siltstone Shale (clays) Nonclastics o Limestone CaCO 3 o Chert SiO 2 (sponge) o Salt NaCl o Gypsum CaSO 4 2H 2 o Coal Organic debris Foraminifera Calcareous Tests o Warm water indicators are: Coccoliths Forams o Cold water indicators are: Radiolarians Diatoms – Siliceous Tests Fossiliferous Limestone – Fencepost Ls (Albertson Hall) Sedimentary structures o Rivers, ocean currents, wind, glaciers o Bedding o Cross-beds o Ripples o Mudcracks o Burrows Bioturbation = biological activity ‘mixes up’ sediment Skolithos = Simple Straight tubes Ophiomorpha = burrow with (fecal) pelleted walls Fossil feces = coprolite Tracks Stratigraphic up? Upper layers = younger /// lower layers = older o Strata = layers = beds Indicators for Stratigraphic Up o Cross-bedding o Ripple marks 2 types of ripple marks Symmetrical is the best kind for determining o Mudcracks o Raindrops o Some fossils o Graded beds Big sediments on the bottom, small on the top o Water current is the opposite direction the marks point Major Sedimentary (Depositional) Environments o Continental o Transitional o Marine Paleographic map o Paleo = ancient o Lake cretaceous = the lake that used to run through the middle of North America Reservoir Rock vs. Source Rock o Source rock is good for oil Lipids “Oil” Shale o Kerogen = a solid waxy hydrocarbon Deltas compact sediments = goes from peat to coal Eastern coal has more pyrite (causes more acid rain) Incorrectly answered questions Hydrolysis is a weathering action of pH that acts mainly on the silicate minerals.
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