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108 Cards in this Set
- Front
- Back
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What are the steps of the scientific method?
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Observations --> HYPOTHESIS --> Tests --> THEORY --> Tests --> SCIENTIFIC MODEL
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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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How is the principle of uniformitarianism applied by geologists?
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The processes currently shaping the Earth are the same ones that shaped it in the past.
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How were lighter elements formed?
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Nucleosynthesis
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How were heavier elements formed?
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Supernovas
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How does density change with depth in the Earth?
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The denser a material, the further towards the center it is
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What are the zones of the Earth?
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Crust/lithosphere (Oceanic and continental), Asthenosphere, Mantle (upper and lower), core (inner and outer)
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Which zones of the earth are strongest? Weakest? Ductile?
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Strongest: Inner core (solid iron)
Weakest/Most brittle: crust Ductile: Asthenosphere |
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How old is the Earth? The Universe?
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Earth: 4.53 billion years
Universe: 13-14 billion years |
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Did Mars undergo the same processes that occurred on Earth?
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Mostly Volcanism
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What are the two sources of heat within the Earth?
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Radioactive decay and stored energy from the Earth's formation
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What is the theory of plate tectonics?
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That Earth's plates are constantly moving, and that crust is being created and destroyed at all times
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What is the driving force behind plate tectonics?
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Convection
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What is the continental drift hypothesis? (Wegner)
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He hypothesized that Earth's plates were constantly in motion, "drifting" about the Earth
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What evidence did Wegner use to support his hypothesis?
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Glacial grooves, matching rocks with matching ages, evidence of tropical climates in cold regions, continental fit, matching plant and animal fossils oceans apart
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What were some of the problems with Wegner's hypothesis?
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He thought ONLY the continents were moving, and he lacked a mechanism to move the plates
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What is Pangea?
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The supercontinent that was made up of all the current continents millions of years ago
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What evidence was found that supports sea floor spreading?
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Mid-ocean ridges and magnetic stripping
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What is magnetic stripping?
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Rocks that have matching polarity on either side of a mid-ocean ridge, shows that the Earth's poles switch every so often
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What is the "Ring of Fire?"
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A ring of volcanoes around the edges of the Pacific Ocean
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What relevance does the "Ring of Fire" have to plate tectonics?
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It marks the outer edges of the Pacific Plate
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What type of boundaries do earthquakes occur at?
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Earthquakes occur at all boundaries.
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What type of plate boundaries do volcanoes occur at?
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Convergent
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What are the three main types of tectonic plate boundaries?
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Convergent, divergent, transform
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What is a convergent plate boundary?
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A boundary where two plates collide, and sometimes one plate subducts beneath another.
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What are the subdivisions of convergent plate boundaries?
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Oceanic-oceanic, oceanic-continental, continental-continental
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What are the defining characteristics of a convergent boundary?
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Mountains and/or volcanoes
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What is a divergent plate boundary?
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A boundary where two plates are separating and new crust is being formed.
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What type of crust is involved with divergent plate boundaries?
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Only oceanic
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What are the defining characteristics of divergent boundaries?
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Mid-ocean ridges, trenches
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What is a transform plate boundary?
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A boundary where two plates move laterally to one another. Very little crust is created or destroyed. They are offset by divergent plate boundaries.
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What is the defining characteristic of a transform boundary?
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Trenches
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What causes the plates to move?
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Continental drift (continental crust basically "floats" on the asthenosphere) and sea-floor spreading
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What is a real-world example of a convergent plate boundary?
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Cascades/Andes mountains
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What is an example of a divergent plate boundary?
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Mid-Atlantic Ridge
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What is an example of a transform plate boundary?
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San Andreas fault
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What is an example of a hot spot?
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Hawaiin islands/Midway
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Why is continental crust so much older than oceanic crust?
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Oceanic crust is more dense than continental; therefore, it is constantly subducted and destroyed.
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What determines which plate will subduct?
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Density
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What is flux melting?
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Occurs at any convergent boundary involving oceanic crust. Water gets subducted along with the crust and lowers the melting temperature, causing it to subduct and be destroyed faster.
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Is any new crust formed where flux melting occurs?
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Some of the oceanic crust that was more buoyant and did not subduct may accrete along the edge of the other plate. Also, when volcanoes are created and erupt, that creates crust.
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What happens to the subducted plate?
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It is destroyed by being melted and mixes in with the magma.
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What is decompression melting?
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Mantle material rises and pressure is reduced, which lowers the melting temperature of the crust.
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Where does decompression melting occur?
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At divergent plate boundaries
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What type of crust forms at places where decompression melting occurs?
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Oceanic
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What are hot spots?
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Mantle plumes shoot through the lithosphere and create a volcano. It stays stationary even while the plates move, so it eventually creates island chains.
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Where would you find a hot spot?
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In the middle of a plate- not on an edge.
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What is the fate of western California?
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Some geologists hypothesize that it will break off from the CA mainland, much like Baja CA did from the mainland of Mexico.
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How fast do plates move?
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~5.5 cm/yr
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What is a mineral?
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A mineral:
-is naturally occurring -is solid -is inorganic -has a crystalline structure -has a specific chemical formula |
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What is an isotope?
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A "version" of an element with a different number of neutrons than the "original"
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What are the two main types of bonds?
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Covalent and Ionic
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Covalent bonds
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Sharing of electrons, form when shells are nearly half full
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Ionic bonds
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Transfer of electrons, form when shells are nearly full
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Which bond is stronger?
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Covalent
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What type of bonding do you find in diamonds?
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Covalent
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How do minerals form?
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All minerals are formed by chemical reactions between elements.
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What conditions cause minerals to form?
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Minerals will form is the temperature of a liquid is lowered below its melting point or if liquids evaporate from a solution, resulting in a precipitate.
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What are the main mineral properties? (There are 9)
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1. color
2. streak 3. luster 4. hardness 5. cleavage 6. fracture 7. density 8. crystal habit 9. special properties (like taste and effervescence) |
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What are mineral polymorphs?
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Polymorphs are two minerals with the same composition and different structures (e.g. graphite and diamond)
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What is the most abundant mineral group in the crust?
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Silicates
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What makes a mineral a gem? (There are 5 criteria)
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1. beauty
2. transparency 3. rarity 4. brilliance 5. durability |
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Where do diamonds come from?
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Diamonds form in the mantle.
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How do diamonds get to the surface of the Earth?
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Through Kimberlite pipes.
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What is the hardness of a diamond (on Moh's scale)
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10
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Study the Rock cycle!!!!
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Did you fill in all the blanks?
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What is the most abundant type of rock in Earth's crust?
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Igneous
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What is the most abundant type of rock on Earth's surface?
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Sedimentary
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What is the most abundant type of rock in oceanic crust?
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Igneous
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How are igneous rocks formed?
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From molten rock (lava)
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What are the two types of igneous rocks?
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Intrusive and extrusive
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Intrusive rocks
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Cool more slowly, have bigger crystals
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Extrusive rocks
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Cool much more quickly, have smaller or nonexistent crystals
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Plutonic
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Another name for intrusive
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Aphanitic
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Crystals are too fine to be distinguished without a microscope
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Phaneritic
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Crystals are clearly visible, but still small
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Porphyritic
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Crystals are different sizes
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Pegmatitic
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Crystals are very large
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Glassy
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NO minerals/ crystals present (obsidian), very smooth
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Pyroclastic
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Fragmental texture
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What do the different textures determine about the rate of cooling?
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The bigger the crystal, the more slowly it cooled.
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Where are magmas generated?
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At hot spots and divergent/convergent boundaries
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How do rocks melt? (There are 3 ways)
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1. Heat Transfer Melting: the temperature is raised (the deeper in the rock is, the higher the temperature)
2. Decompression melting: the pressure is lowered 3. Flux melting: volatiles are added (such as CO2 and H2O) |
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What type of melting occurs at convergent boundaries?
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Heat transfer and flux melting
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What type of melting occurs at divergent boundaries?
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Decompression melting
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What type of magma is produced in Hawaii?
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Mafic
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What type of magma is produced in Yellowstone?
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Felsic
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What type of magma is produced in the Cascades/Andes?
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Felsic to intermediate
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What are the four composition groups of igneous rocks?
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1. Ultramafic: 85-100% mafic minerals
2. Mafic: 45-85% mafic minerals 3. Intermediate: 15-45% mafic minerals 4. Felsic: 0-15% mafic minerals |
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Which compositions have more Fe/Mg? More silica?
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Fe/Mg: Mafic and ultramafic
Silica: felsic |
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What is an example of an ultramafic rock?
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Peridotite
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What is an example of a mafic rock?
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Basalt
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What is an example of an intermediate rock?
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Andesite
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What is an example of a felsic rock?
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Granite
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What is viscosity?
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Resistance to flow
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What viscosity would a felsic magma have?
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Very high
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What viscosity would an intermediate magma have?
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High
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What viscosity would a mafic magma have?
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Low
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What is the correlation between magma temperature and viscosity?
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*Felsic magma=very viscous= low temp
*Mafic magma=low viscosity=high temp |
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How does magma become igneous rock?
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Magma cools, solidifies, and forms silicate minerals
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What is fractional crystallization?
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As magma cools, crystals settle by gravity.
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How does fractional crystallization change the magma composition?
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The mafic minerals are the first to cool, so they settle out first, making the magma more felsic
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Sills
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Horizontal/Parallel/Concordant intrusions
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Dikes
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Vertical/Discordant intrusions
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Batholith
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The largest of the intrusions at over 100 km2
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Mt. St. Helens: type, eruption, composition of lava, viscosity of lava, boundary
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*Type: composite/stratovolcano
*Eruption: Pyroclastic *Lava composition: intermediate to felsic *Lava viscosity: high *Boundary: convergent |
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Mt. Ranier: type, eruption, composition of lava, viscosity of lava, boundary
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*Type: composite/stratovolcano
*Eruption: Pyroclastic *Lava composition: intermediate to felsic *Lava viscosity: high *Boundary: convergent |
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Hawaii: type, eruption, composition of lava, viscosity of lava, boundary
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*Type: shield volcano
*Eruption: Effusive *Lava composition: mafic *Lava viscosity: low *Boundary: hot spot |
