Intro to Geology Week 2 Notes
Intro to Geology Week 2 Notes 100
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This 9 page Class Notes was uploaded by Aubree Broyles on Friday January 29, 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 22 views. For similar materials see Introduction to Geology in Geoscience at Fort Hays State University.
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Date Created: 01/29/16
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
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