Geol 122 Week 1-5 Notes
Geol 122 Week 1-5 Notes GEOL 122
Popular in The Blue Planet: Geology of Our Environment (GT-SC2)
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
Popular in Geology
This 12 page Class Notes was uploaded by Kayla Notetaker on Monday October 17, 2016. The Class Notes belongs to GEOL 122 at Colorado State University taught by Daniel McGrath in Fall 2016. Since its upload, it has received 2 views. For similar materials see The Blue Planet: Geology of Our Environment (GT-SC2) in Geology at Colorado State University.
Reviews for Geol 122 Week 1-5 Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 10/17/16
GEOL SUDY GUIDE EXAM 1 ANSWERS TO THE CHAPTER REVIEW QUESTIONS Chapter 1 Heliocentric versus Geocentric Geocentric was the idea that the solar system revolved around Earth and the that planets orbited around Earth in a circular motion and Earth was the motionless center o This theory was developed by Ptolemy Heliocentric is the model we accept today o The Renaissance created a rebirth in thinking and thus there was criticism of the geocentric model o Copernicus—published evidence for heliocentricity o Kepler—proved planets follow elliptical orbits o Galileo—Observed that Venus has phases like our moon (only possible if Venus orbits the Sun) Through the Enlightenment Newton devised the Law of Universal Gravitation, The Three Laws of Motion, and the mathematics of change (calculus) o Used this to show that planetary orbits are elliptical Doppler Effect—what is it? How did it contribute to our understanding of the universe? Doppler Effect lead to ideas about the formation of the Universe Waves o Compressed: shorter wavelength; higher frequency o Relaxed: longer wavelength; lower frequency o Moving Train Example Moving light waves reveal the Doppler Effect Big Bang theory All of the mass and energy in the Universe was packed into a single small point It exploded 13.7 Ga and has been expanding ever since Age of Universe and the Solar System Our Solar system began 4.56 Ga Age of the Universe is 13.7 Ga Nebular theory—formation of our solar system A 3 , 4 , or 5 generation Nebula (cloud of gas or dust in space) forms 4.56 Ga o We know that our star is not a first generation star because of the heavier elements produced by stellar fusion and supernovae The nebula condenses into an accretion disc The ball at the center grows dense and hot Fusion reactions begin; the Sun is born Dust in the rigs condenses into particles Particles coalesce to form planetesimals o This theory is supported by the configuration of planets o The orbital planes of the planets lie within 3 degree of the Sun’s equator Planetismals accumulate into a larger mass Irregularly-shaped protoplanets develop The interior heats and becomes soft Gravity shapes the Earth into a sphere The interior differentiates into… o A nickel-iron core o A stony (silicate) mantle Soon, a small planetoid collides with Earth Debris forms a ring around the Earth The debris coalesces and forms the Moon The atmosphere develops from volcanic gases When the Earth becomes cool enough, o Moisture condenses and accumulates, and o The oceans are formed Details of our solar system (# of planets, jovial vs terrestrial planets, why?) 8 planets total o Planet is defined as A large celestial body orbiting a star Has a nearly spherical shape Has cleared its neighborhood of other objects o Jovian Planets/Gas-Giant Planets consist of gas and ice and are the outer planets. These include Jupiter, Saturn, Uranus, Neptune o Terrestrial Planets are closer to the Sun (inner planets) and have an outer layer of shell rock and surrounding a center of metallic iron alloy. These planets include Earth, Mercury, Venus, and Mars. Moon—A solid body locked in orbit around a planet The sun—An average star Asteroids—Rocky or metallic fragments Comets—Fragments of ice orbiting the Sun Chapter 2 Oort Cloud, heliosphere, magnetosphere Oort cloud—The edge of our solar system, leftover of our planetary disc when our galaxy formed Earth’s atmosphere—composition, layers Consists of mainly nitrogen and oxygen 99% of the gas in the atmosphere is below 50 km Temperature changes with altitude and each layer of the atmosphere Topography and bathymetry Early view/reasons for layered earth Density Calculations: average density of the Earth is greater than surface density o Therefore, density must increase with depth Shape: A rotating sphere (like Earth) requires a centered mass Role of seismic waves in building a better model Difference between crust, mantle, outer core, inner core Differences between lithosphere/asthenosphere Chapter 5 Mineral Definition Most contain these components… o Naturally occurring o Solid o Formed Geologically o Definable chemical composition o Ordered atomic/crystalline arrangement o Mostly inorganic Crystal Structure/lattices Atoms in a mineral are arranged in an orderly pattern Ordered structure based on atomic patterns A solid with disordered atoms is called a glass Crystal Lattice=crystal faces and angles reflect the internal atomic arrangement o Ordered atoms in crystals form a 3D lattice; Lattices are patterns that form in 3 dimensions o This internal pattern controls Crystal shape, symmetry and mineral characteristics o Lattice atoms are held in place by chemical bonds, forming molecules (two or more atoms bonded together) Chemistry basics—elements, atoms, protons, electrons, different types of bonds Cation—loss of electrons Anion—gain of electrons Lattice atoms are held in place by chemical bonds, forming molecules (two or more atoms bonded together) Strong chemical bond types o Covalent—share o Ionic—transfer of electrons o Metallic—mobile Weak chemical bonds o Hydrogen o Van der Waals Bond characteristics govern mineral properties o Examples: diamond, the hardest mineral, has strong covalent bonds in 3D octahedral lattice o Example: graphite, a very soft mineral, has sheets of hexagonal covalent bonded atoms, weak bonds between sheets How minerals form Through crystal growth; crystals grow as atoms attach to mineral surfaces Growth starts from a seed crystal Growth expands outward as atoms accumulate Crystals grow by… o Solidification from a melt Mineral crystals from when a melt solidifies Quick cooling results in tiny crystals; slow cooling creates large crystals o Precipitation from solution New crystals can form from an aqueous solution when dissolved solids become saturated o Solid-state diffusion New crystals form as rocks are buried to great depths Resulting crystal shape governed by surroundings o Open space—good crystal faces grow o Confined space—no crystal faces How can we identify minerals? Physical Properties o Color Some mineral may exhibit a broad color range Color varieties often reflect trace impurities o Streak A property by which a mineral leaves a crushed powder on an unglazed porcelain plate o Luster The way a mineral scatters light There are two subdivisions Metallic—looks like metal Nonmetallic o Hardness The scratching resistance of a mineral, which is directly linked to atomic-bond strength o Specific gravity Related to density (mass per volume) (density of material)/ (density of water) o Crystal habit/form Ideal shape of crystal faces o Fracture Some minerals lack planes of weakness This is when chemical bonding is equally strong in all directions Breaks along smooth curved surfaces Produces extremely sharp edges o Cleavage The tendency for a mineral to break along lattice planes with weaker atomic bonds Mineral classes Minerals are classified by their dominant ion o Silicates o Oxides o Sulfides o Sulfates o Halides o Carbonates What’s special about silicates? Known as the rock-forming minerals Dominate the Earth’s crust Oxygen and silicon Silica tetrahedral link together by sharing oxygens More shared oxygen=higher silicate to oxygen ratio. Governs… o Melting temperature o Mineral structure and cations present o Susceptibility to chemical weathering Silicon-oxygen tetrahedron and types of silicates Independent Tetrahedra o Shares no oxygens—linked by cations Single-chain silicates Double-chain silicates o Contain a variety of cations Sheet silicates o 2 dimensional sheets of linked tetrahedral o Characterized by one direction of perfect cleavage Framework silicates o All 4 oxygen in the silica tetrahedral are shared Overall observations Melting temperature decreases the more intricate the silica tetrahedron The proportion of silicate in the mineral increases the more complex the tetrahedron Susceptibility to chemical weathering decreases the more complex the tetrahedron Chapter 6 Intrusive vs extrusive igneous rocks Intrusive--Magma solidified below surface Extrusive—erupted from volcanos o Solidified lava o Ash (etc.) Igneous Rocks are formed from melting Formed at temperatures between 650C and 1100C Intrusive settings and landforms Why does magma form? Pressure melting in the upper mantle o Melting is from pressure release and the addition of volatiles (Volatile helps break chemical bonds, creating a melt) Pressure melting in the crust o Heat transfer from rising mantle magma Geologic Environments where decompression melting occurs o Mantle plume, hot spot volcano o Continental rift o Mid-ocean ridge Causes of melting Magma formation in the crust o Heat transfer Rising magma carries mantle heat This raises Temp in crustal rock Crustal rock melts at lower Temp Sources of Heat Magma Composition—both chemical and physical state Magmas have 3 components (solid, liquid, and gas) o Solid—solidified minerals are carried by the liquid o Liquid—the melt itself is comprised of mobile ions o Gas—volatiles dissolved in the melt Dry magma—no volatiles Wet magma—contains volatiles (water vapor, carbon dioxide, sulfur dioxide) Why does it differ? o Magmas vary chemically due to Initial source rock compositions Partial melting Addition and removal of material along conduit Magma mixing o Source rock dictates initial magma composition Mantle source—ultramafic and mafic magmas Crustal source—mafic, intermediate, and felsic magmas Partial melting—what happens? The relative silica content of magma decreases with increasing temperature Assimilation Magma melts the rock it passes through and the assimilated materials change magma compositions Magma melts rock that mixes with the magma and thus changes the magma composition Major types? Why does magma rise and what controls its cooling rate? Cooling rates are influenced by exposure of magma. Thus the more surface area exposed the quicker the cooling rate Also influenced by ground water Cooling times… o Ash=minutes o Lava flow=days to months o Shallow sill=weeks to months o Deep sill=months to years o Deep pluton=centuries to a million years Fractional crystallization/Bowen’s reaction series Fractional Crystallization o As magma cools, early crystals settle by gravity o Melt composition changes as a result o Felsic magma can evolve from mafic magma o Progressive removal of mafic minerals Bowen’s reaction series o How do we classify igneous rocks? Crystalline vs glassy vs pyroclastic Where does igneous activity occur? Why? Subduction zones Mid-ocean ridges Continental rift Hot spots Chapter 7 What is sediment and how is it produced? Sediment o Rock and mineral fragments o Shells o Mineral Precipitates Sediment is the building block for sedimentary rock Sedimentary rocks are a thin cover 4 classes o Clastic—made from Basics of the rock cycle—major processes/ steps ????????? Lithification—transforms loose sediment into sold rock o Burial—more sediment is added onto a previous layer o Compaction—overburden weight reduces pore space o Cementation—mineral Compaction of sand grains and clay minerals Then cementation (new minerals in pore space) Different classes of weathering (physical and chemical) and examples of each that we discussed in class Breakdown of minerals by chemical reactions with the atmosphere or hydrosphere: dissolution, hydrolysis, and oxidation Changes the chemical compositions Dissolution Oxidation Hydrolysis What controls the rate of weathering Properties of parent rock Climate Soils Vegetation Length of exposure Basic structure of soil (zone of leaching, zone of accumulation) Zone of leaching—downward percolating water transports ions and clay Zone of Accumulation—ions and clay accumulate Organic Matter—top layer consisting of decayed plant matter; most prominent in forested areas Surface soil: Layer of mineral soil with organic matter accumulation and soil life. Positive ions are leached from this layer, tends to be porous with a sandy or silly texture, color decreases due to decreased decomposed organic matter Heavily leached horizon: soluble nutrients are lost; lighter in color Subsoil: Enriched layer with precipitates from surface soil layer. Often accumulation of clay—dense structure Parent Rock: Partially weathered bedrock that grades into fresh bedrock. This layer may accumulate the more soluble compounds What controls the amount and maturity of soil? Climate and vegetation Substrate composition Slope steepness and wetness Time How do grains change as the progress away from their source (size, angularity, sorting, maturity)? Clast size decreases with distance of transport Grain roundness increases with distance of transport Sorting: the uniformity of grain size o As it progresses from their source it becomes very well sorted Angularity o Angularity increases with distance from the source What processes transform sediment into sedimentary rocks Lithification—transforms loose sediment into solid rock o Burial—more sediment is added onto a previous layer o Compaction—overburden weight reduces pore space o Cementation—minerals Compaction of sand grains and compaction of clay particles Cementation (new minerals in pore spaces) Different classes of sedimentary rocks (how do each form, how do we classify?) Clastic—made from weathered rock fragments (clasts) o Weathering o Erosion o Transport (via wind, water, glaciers, gravity) o Deposition o Lithification Transforms loose sediment into solid rock Burial—more sediment is added onto a previous layer Compaction—overburden weight reduces pore space Cementation—minerals Biochemical—cemented shells of organisms Organic—the carbon-rich remains of plants Chemical—minerals that crystallize directly from water What are some examples from each class? Bedding and bed forms (ripples, dunes)—how they form Graded beds—bedded layers that fine upward o Transition from coarse to medium to fine grain size o Formed by rapid deposition Bed Surface Markings o Occur after deposition while sediment is still soft Mud cracks—polygonal dessication Indicate alternating wet and dry conditions Fossils—evidence of past life Footprints Shell impressions Cross bedding—how can we tell the direction the grains were transported? Created by ripple and dune migration o Sediment piles up on gentle slope, then slips down the steep face The slip face continually moves downstream Added sediment forms sloping “cross-bedded” layers Differential depositional environments (type of rocks, etc.) Mountain Streams o Water carries large clasts during flood o During low flow, boulders are immobile o Coarse conglomerate is characteristic; as can breccia Sand Dune o Wind blown Chapter 9 What is a volcano and what types of material erupt out of them? A volcano is.. o An erupting vent through which molten rock surfaces o A mountain built from magmatic eruptions The things that erupt form volcanos include: o Lava flows—molten rock that moves over the ground o Pyroclastic debris—fragments blown out of a volcano o Volcanic gases—vapors that exit a volcano What controls lave flow? Viscosity—temperature and composition Silica content controls lava flow and how viscous the lava is How are basaltic and rhyolitic lavas different? How do their eruption styles differ? Basaltic lava has low viscosity and can flow long distances o Mafic lava—low silica, and low viscosity (low resistance to flow) o Basalt flows are often thin and fluid Can flow rapidly Can flow for long distances Pahoehoe—basalt with a glassy, ropy texture Caused by movement of a fluid lava under a congealing surface crust A’a’—basalt that solidifies with a jagged, sharp, angular texture Lava tubes A cooled crust forms on top of a basaltic flow A conduit (lava tube) develops in the flow Pillow basalts Underwater, basalt cools, instantly (no time for flow) It cools to form a rounded blob called a pillow Example of geological setting—oceanic hot spots Rhyolitic (felsic) lava o Rhyolite—the highest silica concentrated and is the most viscous lava o Rarely flows o Often plugs the volcanic vent as a lava dome What types of volcanoes do they each typically form (and what are they called)? Why? What is pyroclastic debris? What form does it come in? Pyroclastic debris is fragmental material ejected from a volcano Includes… o Ash o Lapilli o Blocks and bombs Increasing fragment size in direction of arrow Pyroclastic flows o Avalanches of hot ash that move downslope o High velocities (up to 300 kph); extremely dangerous What are examples of volcanic hazards? Landslides Deposit flows Pyroclastic flows Lava flows Volcanic gas Ash and Lapilli Lahars tsunamis How can we predict an eruption? If the volcano begins to bulge Magma movement causes a change in shape that can be measured with tiltmeters or satellite radar (lnSAR) Danger assessment maps Details on Mt St Helens eruption Geologic settings of volcanic activity mid ocean ridges—spreading axes convergent boundaries—subduction zones continental rifts—incipient ocean basins oceanic hot spots continental hot spots and flood basalts