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45 Cards in this Set
- Front
- Back
What is the scientific method?
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1. observe
2. hypothesize 3. test 4. theory 5. model |
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What is a nebular hypothesis?
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A slowly rotating sphere contracts. Spins faster and then flattens. Matter at the middle becomes proto-sun. Proto-sun becomes dense and hot (nuclear fusion). Gas condenses and collides with dust to form planetismals. Those collide to form planets.
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How old is the Earth?
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4.6 Ga (we can tell from the meteorites and the moon)
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How was the moon formed?
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A Mars-sized body hit earth approximately 4.5 Ga ago, tilted the Earth's spin axis. Material that was hit flew off and formed the moon.
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What is the layered structure of the Earth?
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1. Crust (0-40km)
2. Mantle (40-2890km) 3. Liquid iron outer core (2890-5150 km) 4. Solid iron inner core (5150-6370km) |
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What are the types of seismic waves?
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1. compressional: P-waves; pas through solids, liquids and gasses
2. shear: S-waves; pass through solids ONLY |
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Which crust is denser:
Continental Oceanic |
Continental crust is less dense and thicker than oceanic crust.
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Keypoints about the mantle
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*takes up most of the planet
*high-density silicate minerals *3.4 g/cm3 *upper is relatively strong and rigid *lower is weak and deformable, solid but plastic |
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Keypoints about the outer core
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*mostly made of iron, but also nitrogen, sulfur, and oxygen
*liquid because of temperature *11 g/cm3 |
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Keypoints about the inner core
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*mostly made of iron, but also nitrogen
*solid because of pressure *13 g/cm3 |
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What are the zones of strength?
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*Lithosphere: crust + top of mantle (100 km); relatively cold, strong, and rigid
*asthenosphere: weaker part of the upper mantle; hot, weak, ductile (think hot wax or silly putty solid that flows) |
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What is the temperature gradient?
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Temperature gradient is largely responsible for plate tectonics.
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What happens when plates age?
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They move away from the ridge, cool down, and become denser. They eventually become denser than the underlying mantle, and sink. This causes plate movements.
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What are the leading science paradigms?
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*physics: relatively; quantum mechanics
*biology: evolution by natural selection; DNA *chemistry: atomic structure; thermodynamics *GEOLOGY: PLATE TECTONICS |
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PANGEA!!!
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the super-continent that separated because of plate tectonics
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What are seafloor magnetic anomalies?
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*basalt is extruded at ocean ridges
*basalt records the magnetic field at the time of cooling *crust moves away from the ridges and becomes older *has symmetrical polarity pattern |
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What is strange about the magnetic timescale?
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sometimes a compass points north, sometimes south
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What are some magnetic anomalies?
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*youngest rocks are near a ridge
*oldest rocks are near a continent |
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Divergent boundaries (definition and example)
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*when two continents separate
*East African Rift, Rhine Valley *occurs at zones of upwelling mantle; produces new oceanic crust; basaltic volcanism; causes small shallow earthquakes; high heat flow |
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Continent-continent convergent boundaries (definition and example)
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*when two continents come together
*no where to go but UP! *crustal thickening; folded mountains; earthquakes |
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Ocean-continent convergent boundaries (definition and example)
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*ocean and continent plates coming together
*SUBDUCTION *volcanic mountain chain; folded mountains; deep earthquakes |
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What are subduction zone earthquakes?
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Subduction zone earthquakes are less frequent at increasing depth, but with greater intensity.
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Ocean-ocean convergent boundaries (definition and example)
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*two ocean plates come together
*the denser plate is subducted *oceanic trench; volcanic island arc; deep earthquakes |
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CONVERGENT BOUNDARIES
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*explosive andesitic volcanism
*intrusion of granite at depth *large earthquakes, shallow to deep *metamorphism, folds, thrust faults |
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TRANSFORM BOUNDARIES
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*no igneous activity
*no metamorphism *large, shallow earthquakes *strike-slip faults |
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What's so cool about plate tectonics?
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All the exciting stuff happens on the edge of the plates! (earthquakes, mountains, volcanoes, etc)
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What is the principle of uniformitarianism?
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"The present is the key to the past"
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Define ionic, covalent, and Van der Waals chemical bonding.
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*ionic: attraction of oppositely charged ions; intermediate strenght; example=halite
*covalent: electron sharing; very strong!' example=diamond *Van der Waals (intermolecular bonding): weak electrical bonding; example=water |
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Why do geologists care about bonding?
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Chemical bonding effects:
*crystal structure *cleavage *hardness |
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What are minerals?
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*naturally occurring
*crystalline substance *inorganic *specific chemical composition *MINERALS CANNOT BE DIVIDED MECHANICALLY INTO SMALLER COMPONENTS |
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What class of mineral is most abundant in the Earth's crust?
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Oxides and hydroxides.
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Which minerals are rock-forming?
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Silicates
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How does the Si:O ratio increase?
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*from the mantle to the crust
*olivine--pyroxene--amphibole--micas--feldspars |
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What are some infamous cation substitutions?
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Fe2+ and Mg2+
K+ and Na+ Al3+ and Si4+ Ca2+ and Na+ |
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What (and explain) are the physical properties of minerals?
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*hardness: determined by the strength of a mineral's chemical bonds
*cleavage: how a rock will slit away |
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Important information about minerals
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*important as natural resources, for Earth's structure and acts as 'archives' of the geologic past
*compositions reflect the abundance of elements (Si and O most common in the crust) *compositions vary within defined limits (for example, by cation substitution) *properties reflect composition and bonding |
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minerals found in mantle rocks
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*olivine
*pyroxene |
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minerals found in crustal rocks
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*amphibole
*mica *feldspar *quartz |
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What are rocks?
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Rocks are the building blocks of our planet. They are naturally occurring aggregates of minerals; some rocks are aggregates of non-minerals solid matter (coal or obsidian)
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How do we ID rocks?
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*mineralogy (what minerals make up the rocks)
*texture: shapes and sizes of the mineral grains and how they are put together |
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What are the rock types?
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*igneous: melting of rocks in hot, deep crust and upper mantle
*sedimentary: weathering and erosion of rocks exposed at surface *metamorphic: rocks under high temperatures in deep crust and upper mantle |
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Igneous rocks
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*Extrusive: form when magma erupts at the surface, rapidly cooling to fine ash or lava and developing tiny crystals.
*intrusive: crystallize when molten rock intrudes into unmelted rock masses in Earth's crust *intrusive are coarser. *low Si=darker; high Si=lighter |
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Sedimentary rocks
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*form from weathering and deposition
*created by weathering, transported by erosion, deposited as sediment on land or in water, form parallel layers, lithify under water, precipitated, deposited in the ground. |
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Metamorphic rocks
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*form from heat and pressure
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ROCKS
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*rocks are aggregates of minerals
*individual minerals in a rock retain their own properties *properties of the rock are controlled by 1. minerals in the rock 2. the formation process of the rock *igneous, sedimentary, and metamorphic rocks *the continual transformation of Earth materials from one rock type to another is known as the rock cycle |