Geology 101: Terms and Definitions, Quizzes of Geology

Download Geology 101: Terms and Definitions and more Quizzes Geology in PDF only on Docsity! TERM 1 What is Geology? DEFINITION 1 -The science of studying and understanding planet Earth-- Inside and outside. TERM 2 Physical Geology DEFINITION 2 Keyword: NOW Materials composing Earth and its processes at its current condition TERM 3 Historical Geology DEFINITION 3 Keyword: PAST Origin of the Earth and its development through time -Pangaea etc. TERM 4 Geology, People, and Environment DEFINITION 4 Geology affects where people live and how they adjust to their environment -Natural hazards, resources, world population growth etc. - Ex. New Orleans- houses built off the ground TERM 5 Geologic Time DEFINITION 5 Involves vast time spanses (millions/billions of years) because many geologic processes are very gradual 100's of years ago is considered recent Rocks from the 4.5 billion years ago considered old-ish TERM 6 Relative Dating DEFINITION 6 Dates are placed in their proper order without knowing specific age in years Ex. Susie is older than her brother In geology, rocks on top are younger than rocks on bottom TERM 7 Absolute Dating DEFINITION 7 Accurate dates to events using years, decades, etc. Ex. Susie is 10 years old and her brother is 8 therefore she is older TERM 8 Scientific Method DEFINITION 8 Gathering facts through observations and formulating hypotheses and theories based on these observations TERM 9 Hypothesis DEFINITION 9 A tentative (untested) explanation based on observation - "educated guess" TERM 10 Theory DEFINITION 10 A well-tested and widely accepted view TERM 21 Crust DEFINITION 21 - Very thin - Continental Crust: -Thicker-- Less dense "floats higher" - Composed of silica and oxygen -Oceanic Crust: - Thinner-- More dense "floats lower" - Composed mainly of magnesium (Mg) TERM 22 Lithosphere DEFINITION 22 - The rigid shell of rock ~ 70km (43mi) - Makes up Earth's tectonic plates - uppermost mantle + crust - Crust and mantle separated by "Moho" Density ~ 2.7 -3.0 g/cm3 TERM 23 Mohorovic Discontinuity DEFINITION 23 The Mohorovii discontinuity () (MOE-HOE-ROE-veeech-eeech), usually referred to as the Moho, is the boundary between the Earth's crust and the mantle. TERM 24 Asthenosphere DEFINITION 24 - Liquid plastic - Drives the movement of tectonic plates - Includes the mantle - Uppermost mantle is also considered part of the lithosphere TERM 25 The Core DEFINITION 25 - An iron rich sphere with a radius of 3,471 - Outer Core - Liquid iron-nickel-sulfur -- Less pressure allows liquid form - 2,255 km thick -Density ~ 10-12 g/m3 - Inner Core -Solid iron-nickel alloy -1,220 km radius -Pressure keeps metal in a solid state TERM 26 Basic Idea of Plate Tectonics DEFINITION 26 - Earth's surface is composed of a few large, thick plates that move slowly and change in size - Intense geologic activity concentrated at plate boundaries - Explains global distribution of volcanoes, earthquakes, faults, mountain belts, etc. TERM 27 Continental Plates DEFINITION 27 - Each continent pretty much has its own plate and each plate moves around the Earth. -Major plates: -Pacific -African -North American - Eurasian -South American - Indo- Australian TERM 28 Alfred Wegner DEFINITION 28 - German meteorologist (1912) - Originally proposed "Continental Drift" theory -Used several positional observations to support his idea and hypothesized that all of the present day continents were once part of a supercontinent : PANGAEA TERM 29 PANGAEA DEFINITION 29 - Pangaea to present spanning 225 million years - Puzzle piece coastlines of Africa & South America - Geological evidence - Rock picture: Basalt (lava flows), Sandstone (shale), coal, glacial till-- Glossopteris fossils in sandstone and coal - Wegner noted almost identical Paleozoic rocks and fossils in South America, Africa, India, Antarctica, and Australia TERM 30 PANGAEA: Glacial Evidence DEFINITION 30 - Wegner reassembled continents into supercontinent Pangaea - Pangaea intially separated into Laurasian and Godwannaland glaciers TERM 31 Paleomagnetism DEFINITION 31 - Rock magnetism-- determination of magnetic poles' locations over time - Paleomagnetism uses mineral magnetic alignment direction and dip angle to determine the direction and distance to the magnetic pole when rocks formed TERM 32 Apparent Polar Wandering DEFINITION 32 - This proves plate tectonics because we assume, when Pangaea happened, magnetics are more similar and can be explained - Apparent polar wander-- curves for different continents suggest real movement relative to one another TERM 33 Seafloor Spreading DEFINITION 33 - 1962-- Harry Hess proposed seafloor spreading - Seafloor moves away from mid-oceanic ridge due to *mantle convection* *Hot mantle rock rised under mid-oceanic ridge. Seafloor rocks and mantle rocks beneath them cool and become MORE DENSE. When sufficiently cool (therefore dense) these rocks may sink back into the mantle at subduction zones* - Downward plunge of cold rocks gives rise to oceanic trenches TERM 34 Plates and Plate Motion DEFINITION 34 - Tectonic plates are composed of relatively rigid lithosphere - Lithosphere thickens and age of seafloor increase with distance from mid-oceanic ridge -Plates "float" upon ductile asthenospheres -Evidence: Global distribution of seismic and volcanic activity - Plate margins are outline by seismic belts -Cause: Plates are not stationary and slowly drift over the denser asthenosphere. "Convection currents" drive movement. TERM 35 Slab Suction & Ridge Push DEFINITION 35 1. Warm magma rock rises to the ridge and forms a mountain chain 2. Gravity pulls rock down to make new ocean floor therefore makes space for more hot rock to rise 3. New sea floor is being pulled into the mantle at the end of a plate TERM 46 Color DEFINITION 46 - Color is diagnostic for some minerals - Olivine is olive green - Azurite is always blue -Some minerals may exhibit a broad color range - Ex. Quartz (clear, white, yellow, pink, purple, etc.) - Color varieties often reflect trace impurities TERM 47 Streak DEFINITION 47 - Color of a mineral crushed on unglazed porcelain - Streak is often a useful diagnostic property -Congruent streak-- streak color same as mineral (magnetite) -Incongruent streak-- streak color different than mineral (chromite) TERM 48 Luster DEFINITION 48 - The way a mineral scatters light - Two subdivisions - Metallic - looks like metal - Nonmetallic: -Vitreous (glassy) -Pearly - Satiny - Earthy (dull) -Silky - Adamantine (brilliant) -Resinous TERM 49 Hardness DEFINITION 49 - Scratching resistance of a mineral - Hardness compared to Mohs Hardness Scale - Fingernail (2.5) TERM 50 Specific Gravity DEFINITION 50 - Related to density (mass per volume) - Mineral weight over weight of equal water volume - Pyrite- Heavy (SG 5.0) - Feldspar- Light (SG 2.6) -Pyrite "feels" heavier than feldspar TERM 51 Crystal Habit DEFINITION 51 - Crystal habit is the ideal shape of crystal faces - Ideal growth requires ideal conditions -Many terms are used to describe habit: - Cubes -Dodecahedra -Octahedra - Compound forms -Blades - Rhombohedra -Hexagonal Prisms - Tetragonal prisms TERM 52 Fracture DEFINITION 52 - Some minerals lack planes of weakness due to equal molecular bonds in all directions - These minerals do not have cleavage, they have fracture - Ex. Quartz displays conchoidal fracture -Shaped like the inside of a clam shell -Breaks along smooth curved surfaces - Produces extremely sharp edges TERM 53 Cleavage DEFINITION 53 - Tendency to break along planes of weakness - Cleavage produces flat, shiny surfaces - Described by number of planes and their angles - Sometimes mistaken for crystal habit Ex. 1 direction 9 (mica), 2 directions @ 90* (potassium feldspar) , 2 directions NOT @ 90* (amphibole), 3 directions @ 90* (halite), 3 directions NOT @ 90* (calcite TERM 54 Mineral Compositions DEFINITION 54 - Only about 50 minerals are abundant - 98.5% of crustal mineral mass is from 8 elements -Oxygen (O) 46.6% -Silicon (Si) 27.7% -Aluminum (Al) 8.1% -Iron (Fe) 5.0% - Calcium (Ca) 3.6% - Sodium (Na) 2.8% -Potassium (K) 2.6% -Magnesium (Mg) 2.1% TERM 55 Mineral Classes DEFINITION 55 - Minerals are classified by their dominant anion Silicates (SiO2)4- Rock forming minerals Oxides O2- Magnetite, Hematite Sulfides S- Pyrite, Galena Sulfates (SO4)2- Gypsum Halides Cl- or F- Fluorite, Halite Carbonates (CO3)2- Calcite, Dolomite Native Elements Cu, Au, C Copper, Graphite TERM 56 Silicate Minerals DEFINITION 56 - Silicates are know as the rock-forming minerals - They dominate the Earth's crust -Oxygen and silicon -Make up 94.7% of crustal volume and 74.3% of crustal mass - The anionic unit is the silica tetrahedron -4 oxygen atoms are bonded to 1 silicon atom (SiO4 4- ) -Silicon is tiny; oxygen is huge