Geol 1005 Study Guide PDF

Chapter 1 - Planet and Population Key terms Accretion - gravitational collection of dust and debris Paradigm - framework under which a discipline operates (example natural selection) A. Earth in Space and Time a. Crust - composed of oxygen and silicon b. Mantle - compo...

Chapter 1 - Planet and Population Key terms Accretion - gravitational collection of dust and debris Paradigm - framework under which a discipline operates (example natural selection) A. Earth in Space and Time a. Crust - composed of oxygen and silicon b. Mantle - composed of iron, magnesium, silicon and oxygen c. Core - composed of iron and nickel i. Outer core - liquid, magnetic field source ii. Inner core - is solid d. Understanding of composition - direct drilling of the earth, study of earthquakes, examining moon rocks e. Earliest life forms - cyanobacteria (introduces oxygen) B. Geology, Past and Present a. Deep time - involves thinking on a scale of millions/billions of years b. Scientific method - Karl Popper, based on falsification C. Nature and Rate of Population Growth a. Growth rate = change in # / change in time b. Doubling time - length of time required for a population to double in size (D=70/r) c. Exponential Growth -> density independent (does not depend on # of individuals in a population), also known as a J-shaped curve D. Impacts on the Human Population a. Population growth is logistic or density dependent (growth rate slows down as the population size grows larger) i. Results in an s-shaped curve b. Carrying capacity / K - the maximum number of individuals a habitat can support Chapter 2 - Rocks and Minerals Lithification -> requires compaction and cementation A. Atoms, Elements, Isotopes a. Isotopes - Elements that contain a different number of neutrons (example C12 is 99% of carbon C14 is very rarer) b. Half life - the time it takes for half o f the atoms of a radioactive isotope to decay into a more stable form i. Can determine the ages of fossil as old as 50,000 years  c. Compound - two or more chemical elements that bond together i. Ionic - based on attraction between oppositely charged ions (cation + anion) ii. Covalent - atoms share a pair of electrons B. Minerals a. Mineral characteristics - Naturally occurring, inorganic, solid, definable chemical composition, crystalline structure, formed by geological process (either solidification of molten rock or precipitated by organisms) b. Physical Properties of minerals i. Color ii. Streak iii. Hardness - mohs hardness scale is used to identify minerals (relative) iv. Cleavage v. Fracture (smoothly curving surface is called a conchoidal fracture) vi. Luster (metallic vs non metallic) vii. Specific Gravity c. Types of Minerals i. Silicates (ex. Quartz) ii. Non Silicates 1. Carbonates 1 carbon bound to 3 atoms of oxygen (ex. Limestone) 2. Sulfates 1 sulfate bound to 4 atoms oxygen (ex. Pyrite) 3. Oxides - metal cations to oxygen 4. Native elements (single element) C. Rocks a. Rock - naturally occurring solid that is made up of one or more minerals b. Igneous Rock - cooling from molten material i. Plutonic - form within the Earth (underground), coarse grained GRANITE ii. Volcanic - molten rocks created at or above the Earth's surface, fine grained (from lava) BASALT iii. Porphyry - rock that begins as plutonic and then cools volcanic iv. Sill - horizontal layer of magma vs. Dike - vertical layer of magma v. Mafic - rich in mag and iron, Felsic - rich in silica c. Sedimentary rocks - rocks that form at or near the surface of the Earth in one of several ways i. Cementing, Accumulation of organic matter, Precipitation of minerals ii. Clastic sedimentary rock vs Chemical sedimentary d. Metamorphic rocks - formed when a pre existing rock undergoes a solid-state change in response to pressure and temperature (metamorphism) i. Contact metamorphism - when magma rises from the earth and changes the surrounding rocks  ii. Foliation - a parallel layering in a metamorphic rock, subjected to stress (examples, Slate, Phyllite, Schist, Gneiss) iii. Nonfoliated metamorphic - quartzite, marble Chapter 3 - Plate Tectonics Key terms Magnetic declination - difference in angle between the geographic north pole and the magnetic north pole A. Continental Drift and Plate Tectonic Theory Evidence a. Continental drift - hypothesis by Wegener - founding base for plate tectonics, except the entire continents were not moving b. Earth Convection currents -> allowed warm fluids rising to push seafloor apart into Mid ocean ridges (MORS) c. Subduction -> one plate (the subducting plate) sinks into a trench as mantle begins to cool and fall, while the one plate (overriding) stays on the surface d. Magnetic Stratigraphy i. Magnetic poles are constantly moving and sometimes align with geographic poles (normal polarity) and other times do not ii. Magnetic reversals results in differences in crystals in rocks spreading from MORs allows dating of the rocks e. Rock Deformation i. Elastic deformation - (temporary strain on object, seen in the Lithosphere) ii. Plastic deformation / Folding - (rocks do not return to original unfolded shape after stress is removed, seen in the Asthenosphere) iii. Brittle deformation / Faulting - (rocks break or shatter) B. Plate Interactions and Movements a. Plate-Plate Interactions i. Divergent margins (plates move apart, creates crust) ii. Convergent (plates collide, forming a subduction zone, destroying crust) iii. Transform margin (plates slide past each other, doesn’t impact crust) b. Theories on what drives plate motion i. Convection Cell model ii. Slab-pull model iii. Ridge push model Chapter 4 - Earthquakes Key terms Focus - the point on the fault within the earth from which earthquake energy propagates Epicenter - the point on the Earth's surface directly above focus A. Earthquake Terminology a. Earthquakes - a release of built up stress in the lithosphere, typically occurring along faults b. Faults - planar breaks in rock, displacement of one side relative to other along faults i. Creep (aseismic slip) - gradual & relatively slow movement along faults ii. Wall above the fault -> hanging, Wall below the fault -> foot wall 1. Normal fault -> hanging wall ⬆️ 2. Reverse fault -> hanging wall ⬇️ (thrust -> low angle reverse fault) iii. Strike slip faults – plates slide past one another horizontally, no up or down motion (Right lateral and Left lateral) B. Seismic Waves a. Body Waves (P and S waves) - pass through earth interior, while surface waves travel along the Earths surface i. P waves - compressional body waves (the fastest waves and can pass through solid and liquids) ii. S waves - shear body waves, slower moving and cannot pass through liquids b. Seismometers - measure and record ground movement in vertical and horizontal directions c. Magnitude - measured by the logarithmic Richter scale i. Intensity - a qualitative/subjective scale, measure by a Mercalli intensity scale C. Earthquake Hazards and Mitigation a. Offset - how much the ground has moved on either side of a fault b. Earthquake Hazards i. Tsunamis ii. Landslide iii. Aftershocks iv. Soil liquefaction - soil, clay and ash act as a liquid under Earthquake conditions c. Earthquake prediction i. Seismic gaps ii. Recurrence intervals Chapter 5 - Volcanoes hello Key terms Viscosity - resistance to flow (higher = more resistant), depends on temperature and silica content A. Magma Sources and Types a. Major elements that affect a Magmas composition - Silica, Iron, Magnesium b. Mafic lava vs. Felsic lava i. Mafic - has low silica content and high mineral content, low viscosity ii. Felsic - has high silica content and low mafic mineral content, high viscosity  iii. Intermediate lava (example - andesite) c. Magma formation causes i. Reduction in pressure - material rises from mantle to shallower regions, reduction in pressure promotes melting of the rock ii. The addition of fluids - subducting plate carries seawater embedded with it down into the earth, causing the water to heat into the overlying rocks B. Styles of Volcanic Activity a. Fissure eruption - magma rising up through cracks in the lithosphere b. Ring of Fire - line of volcanoes that rim the Pacific ocean, overlying a ring of subduction zones c. Types of Volcanoes i. Shield Volcanoes - broad, gentle domes, form low viscosity, basaltic lava ii. Cinder cones - from cone shaped piles of small basaltic rocks iii. Composite/Stratovolcanoes - steep slopes with intermixed layers of lava, tephra and blocky flows C. Volcanic Hazards a. Lava b. Pyroclastics - fragments of hot rock and spattering lava that erupt explosively out of the volcano i. Nuees ardentes - type of pyroclastic flow where fine ash and hot gases combine c. Lahars - ash flows that combine with water d. Toxic gasses - such as carbon monoxide, hydrochloric acid e. Steam explosions f. Examples of Volcanic hazards in the U.S - Cascade Range, Aleutians, Yellowstone Caldera