Summary - Earth\'s Dynamic Environment​ - Study Guide 1 & 2 PDF

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Summary

Earth's dynamic environment​ - Study guide 1 & 2...

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GSCI 1050 Study Guide Test 1

UNIVERSE Unifying theory of Geoscience: we want to understand the universe. Renaissance brought new more accurate scientific discovery -

Heliocentric – sun is the center of the universe Galileo observed moons orbiting Jupiter Newton – planet motion explained by Theory of gravity Natural laws govern natural events

Big Bang Theory: OCCURRED 13.8 GA AGO Initial changes happened within minutes and later changes occurred over millions of years The temperature had to fall below one billion degrees to allow atoms to form As the universe cooled, atoms and molecules accumulated in patchy clouds of gas called nebulae Nebulae condensed and heated to become spinning accretion disks, then protostars, then stars. The process of atom creation, termed big bang nucleosynthesis, produced only small atoms like helium, lithium, beryllium, and boron. Larger atoms developed in later generation stars and in supernova explosions. HUBBLE was the first to observe that the universe in continuously expanding with the DOPPLER EFFECT. Doppler Effect: Change in wave frequency in relation to the source of emanation. Things moving away from you and making noise develop a LOWER frequency. Things moving toward you and making noise have a HIGH frequency. DOPPLER EFFECT W/ Light: Wavelength of blue light is LESS than that of red light, viewing the universe from Earth displays red light meaning the galaxy is moving away from us. Galaxy: Massive gravitationally bound system that consists of starts, planets, gas, dust, and dark matter STARS: 1. 2. 3. 4. 5.

The universe cooled and expanded First molecules (hydrogen and helium) form Molecules accumulate into clouds called nebulae Nebulae condense into disks with a center of hot gas called protostars When protostars reaches 10 m degrees, hydrogen fuses in to helium creating a star

Stellar nucleosynthesis created heavier elements 6 – 26 (C to Fe) Supernova created the elements above atomic number 26 Supernova – explosion of radiation, can fuse elements with high atomic masses. New nebulae are formed from supernovas which form new stars. Nebular Theory Center of nebula, masses condense to form the sun Sun got hotter and began to fuse hydrogen, dust left around the sun while gas drifts away Collisions of molecules and particles form a circumstellar disk, IE planet started forming around the sun Gases and volatiles were ejected from the inner portion of the disk as the sun got hotter, inner disks remained as dense planets Gases that were pushed out created gas giants with volatiles, less dense than planets Solar System is defined by Suns Gravity Kuiper Belt is 50 Astronomical Units out, past Neptune’s orbit, filled with icy objects, volatiles from universe formation Solar Winds – stream of charged particles that prevent the collection of hydrogen and helium in planet formation. BOUNDED by the heliosphere Asteroids: Small bodies of rock and metal that orbit the sun, too small to be shaped by gravity, most on the belt between Mars and Jupiter Comets: ICY planetesimals that orbit the sun elliptically. Develop their coma (tail) when near the sun – evaporating gas and dust with tails that point away from the sun.

EARTH SYSTEM Earth’s Magnetic Field North and South poles are at opposite geographic locations, the north arrow on a compass will point to the south pole Magnetism flows South to North, and then North flows around and outside back to North Magnetic field extends out of earth and forms the magnetosphere: the region shielded from solar winds Magnetosphere deflects most of the solar winds that WOULD strip apart atmosphere, teardrop shape from solar wind distortion

Van Allen Belts contain solar wind particles (nuclei of atoms from supernovae) that moved quickly enough through the magnetosphere only to get caught by a stronger magnetic field. Aurorae – Charged particles that get channeled along magnetic field lines and cause gases in polar regions to glow. North: aurora borealis South: aurora australis Earth System Atmosphere, Biosphere, Cryosphere, Lithosphere, Hydrosphere ATMOSPHERE: Mostly N2 and O2, thins away as you move further from earth Pressure, density, and oxygen all decrease with elevation Trace of Argon, Carbon Dioxide, Neon, Helium, CH4, Kr Earth Topography Most land lies within 1km of sea level Most ocean floors are close to 5km in depth 70% is water Composed of 4 elements: Iron, oxygen, silicon, magnesium Earth Materials Organic Compounds – remains of living creatures Minerals – naturally occurring crystalline solid Glasses – form by rapid cooling Rocks – aggregates of minerals, grains and glass Sediments – loose mineral grains Metals – solids composed of metal atoms Melts – rocks that have been heated to liquid Volatiles – materials that turn into gas on surface Wiechert: metal must be in Earth, metal must be at center, earth must be solid (no tides on land) Wiechert model: Earth is like an egg. Thin, light crust (shell), thicker denser mantle (eggwhite) inner most dense core (yolk)

Seismic waves can help figure out earth’s interior. Places with greater densities make waves travel slower: we can figure out where the densities change As you go deeper into the core, it gets hotter from the core and heavier from overlying rock Geothermal Gradient: The rate at which temperature increases as depth increases, can be 15-50 degrees per KM Crust  Moho  Upper Mantle  Transition Zone  Lower Mantle  Liquid Outer Core  Solid Inner Core Crust: Upper portion of tectonic plates, Continental Crust (density 2.7, thickness 35-40km) and Oceanic Crust (density 3, thickness 7-10km) exist here. 93% of crust is Oxygen Mantle: 3 layers (upper, transitional, lower) and is made of only peridotite. CONVECTION in the mantle drives plate tectonics. Core: IRON sphere with an outer and inner core. Outer core generates magnetic field, solid inner core Lithosphere: crust and upper mantle. Non-flowing and rigid Asthenosphere: Upper mantle below lithosphere, soft solid. SHALLOW under ocean DEEP under continent

PLATE TECTONICS Wegener, first to theorize all continents fit together: PANGEA. PROBLEM: He couldn’t explain how/why 1. 2. 3. 4.

Fossils of plants and animals on opposite sides of ocean Continents appeared to fit together Similar rock layers found on opposite sides of ocean GLACIAL EVIDENCE, deposits from one glacier one different continents

The magnetic field has reversed many times and is visible in the ocean floor Mid-ocean mountain ranges run through the middle of oceans, deep trenches by volcanic island chains Tectonic Plates: Lithosphere (crust and upper mantle) that is broken into fragments and in motion over asthenosphere. Moved by creation of new crust and subduction of old crust. Margins near plate boundaries are ACTIVE, far PASSIVE DIVERGENT: Plates move apart and create new lithosphere along mid ocean ridges. Youngest ocean floor at the ridge. CONVERGENT: Plates coming together, old lithosphere is recycled into mantle Subduction: Oceanic plate colliding with itself or continental plate

SUBDUCTION ZONES Accretionary Prisms – Sediments that are scraped off of a subducting plate Volcanic Arc – chain of volcanoes on the above plate where the descending plate is melting, CURVED Back Arc Basin – Marginal sea between an island arc and continent, Continental with continental builds mountains TRANSFORM: No new plate forms and no old plate is consumed, earthquakes but no volcanism

MINERALS AND THE ROCK CYCLE Minerals have: -A definite chemical composition: definite chemical formula, ANIONS -naturally occurring: natural geologic processes -solid: maintain its shape -inorganic: no carbon-hydrogen bonds -crystalline structure: atoms are arranged in a specific order: crystal lattice. Any solid with a disordered structure is glass Crystal: Single, continuous piece of solid bound by the face. Held in place by chemical bonds, bonds define structure. Physical properties depend on what atoms are present, how they’re arranged, and type of bonds present. Strong Bonds: Covalent, makes the crystal harder and raises melting point Weaker Bonds: Van der Waals, softer and lower melting point Atoms pack together depending on the size and charge: Large Central Cation = large number of anions Small Central Cation = small number of anions FORM 5 WAYS: Solidification from a melt, precipitate from solution, solid state diffusion, bio mineralization, and precipitate from gas. Crystal growth can be restricted Anhedral Crystals: grow in confined spaces, no faces MOST CRYSTALS ARE ANHEDRAL

Euhedral Crystals: grow in an open cavity, good faces CAN BE DESTROYED BY Melting, dissolving, or chemical reaction Minerals HARDNESS is its ability to resist scratches, strength of ATMOIC BONDS Talc, Gypsum, Calcite, Flourite, Apatite, Orthoclase, Quartz, Topaz, Corundum, Diamond FRACTURE: Minerals break in ways that reflect atomic bonds, equal strength of bonds in all directions (quartz, glass) CLEAVAGE: Tendency to break along weaker planes of atoms, produces flat shiny surfaces SILICATE MINERALS: divided into groups based on how tetrahedra share oxygen. The amount of shared oxygen determines Si:O ratio. Si:O RATIO controls melting temp, mineral structure and cations, susceptibility of chemical weathering. GROUP 1: 1:4, Independent Tetrahedra LINKED BY CATIONS GROUP 2: 1:3, Single Chains SHARE 2 OXYGEN GROUP 3: 2:7 Double Chains SHARE 2-3 OXYGENS GROUP 4: 2:5 Sheet Silicates SHARE 3 OXYGENS GROUP 5: 1:2 Framework Silicates ALL OXYGEN SHARED

ROCKS Igneous rocks: formed by melting and cooling MAGMA – melted rock below surface LAVA - melted rock above surface Magma: Formed by partial melting in CRUST and UPPER MANTLE. Melting caused by DECOMPRESSION: hot rock is carried to shallow depths by MANTLE PLUMES, CONTINENTAL RIFT ZONES, Mid-Ocean Ridges, VOLCANIC ARC/Subduction VOLATILES: Lower melting temp, such as water HEAT TRANSFER: Rising magma carries heat which raises temp by crust and melts. Magma is made of solid, liquid, and dissolved trapped gas. Distinguished by silica %. Felsic and intermediate CRUSTAL. Mafic and Ultramafic MANTLE Felsic – 66-76%

Intermediate – 52-66%

Mafic – 45-52%

Ultramafic – 38-45%

Magma varies because: source rock, partial melting, assimilation, magma mixing Magma has a tendency to rise because it is buoyant and gets squeezed up by pressure of surrounding rocks. Magma has viscosity which is controlled by: TEMPERATURE: hot = low viscosity / cool = high viscosity VOLATILES: more present = low v / less present = high v SiO2: more mafic = low v / more felsic = high v IGNEOUS ROCK IS FORMED EXTRUSIVELY BY: Lava flows, cooled fragments, particles of volcanic glass, volcanic rock. VOLCANOES Cools QUICKLY EXTRUSIVELY: fine grains, crystals have no time to grow APHANITIC Cools SLOWLY INTRUSIVELY: coarse grains, crystals can grow PHANERITIC PORYPHYRITIC: mixture of coarse and fine grains PLUTONS: Pockets of leftover magma that cools within the earth, resistant to erosion so may remain as a hill

Sedimentary Rocks Form from the depositions at Earths surface, material for all sedimentary rocks provided by: WEATHERING: Breakdown of exposed rock into smaller fragments/dissolved ions Physical – Breakdown of rocks by physical forces, abrasion Chemical – Breakdown of rocks by changing chemical composition (dissolving in water) 1. Clastic – fragments of original rock made in the ocean/under pressure 2. Biogenic – clastic or chemical, biologically induced a. Biochemical – derived from SHELLS of organisms (limestone, chert) b. Organic – made of carbon, found in tropical wetlands (coal, oil shale) 3. Chemical – minerals deposited when water evaporates COMPOSITION: Siliceous – quartz rich Argillaceous – clay rich Carbonate – calcite or dolomite 70-85% are S and A EROSION: Transportation of sediments by gravity, water, wind, or ice LITHIFICATION – transforms loose sediments into solid rock...