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Unit 3
| Question | Answer |
|---|---|
| Continental Drift Theory | all the continents were joined together forming a super continent called Pangaea. |
| Continental Drift was proposed by who? | Alfred Wegener a German meteorologist |
| Tragic Flaw of continental drift | could not explain the mechanism of movement and how continents could move without fracturing |
| Evidence of continental drift | puzzle like fit of continental coastlines. fossil evidence. mesosaurus . glassopteris |
| paleoclimatology | study of ancient climates- matching types of sedimentary rocks that form only in specific climates. |
| Sea Floor Spreading Theory | New seafloor forms at the mid ocean ridges- underwater mountains from rising magma and is destroyed at deep sea trenches. proposed by harry hess |
| Paleomagnetism | study of earth's iron bearing minerals pointing toward south or north |
| evidence of sea floor spreading | magnetic reversals. as molten rock cools the magnetic minerals align with the poles. earth's magnetic poles reverse on an average of every half million years. there are matching successive alternating bands of reversals on each side of the mid ocean |
| plate tectonics theory | earth's outer layer id a 100km thick shell of brittle rigid rock that is broken in section called plates.the plates float on a partially melted layer within the mantle called the asthenosphere . convection currents withing the athenosphere drives the lith |
| plate tectonic evidence | earthquakes occur in limited belts along the plate boundaries . volcanoes and mountain buildings occur. 12 major plates |
| convergent boundaries | places where 2 tectonic plates are moving towards each other. |
| subduction | when one plate is descending below the other plate. |
| collision | a continent is pulled toward a subduction zone by an ocean basin but it cant subduct because continental rock is too buoyant, so it collides |
| volcanic island arc | series of volcanoes formed on a continental plate. |
| divergent boundary | move away from each other *mid ocean ridges |
| seafloor spreading ( divergent boundary) | seafloor forms at mid ocean ridge |
| rift | fault bounded valley at a plate boundary |
| rift valley | divergent boundary on a continent * great rift valley |
| transform boundary | when 2 plates slide past each other horizontally. most usually in oceans .long faults 200km in length *San Andreas |
| shield volcano | non explosive , little gas , flows fast- not much . broad base, gentle slope circular base. layer after layer of basaltic lava * mona loa |
| cinder cone volcano | explosive, lots of gas and flows slow, lots of silicon. small, less than 500 m, steep slop, concave. tephra- cinders ash, explodes high in air + piles up around vent. *found in java |
| composite volcano | explosive+ non ex. , lots of gas, silicon and water. largest, broad base, medium slope, concave.layers of tephra alternate with lava. Mt. Rainier and Mt St. Helens |
| tephra | sod materials that comes out of volcano . * ash, dust, bombs |
| pyroclastic flows | gas, ash, + other tephra rapidly moving down slope |
| pluton | intrusive intrusion rock bodies *sills, dikes, stocks, batholiths |
| crater | a bowl shaped depression at the top of a volcano around the vent- usually less than 1 km in diameter |
| caldera | larger depression that a crater. up to 50 km wide. forms when summit or side of a volcano collapse into the magma chamber. *crater cave |
| volcano | accumulation of lava over time to form a mountain |
| vent | an opening in the crust through which lava erupts |
| pipe | connects the crater to the magma chamber. |
| earthquake | natural vibrations of the ground caused by movements along gigantic fractures in the earth's crust |
| stress | force per unit area acting on a material |
| compression | stress that decrease the volume of a material |
| tension | stress that pulls a material apart. |
| shear | stress that causes a material to twist |
| strain | deformation of materials in response to stress |
| ductile deformation | deformation of materials by strain that produce permanent deformation |
| faults | a fracture along which movement occurs. happens when stress is applied too quickly |
| reverse fault | result of horizontal compression- crust shortens |
| normal fault | result of horizontal tension - crust extended- partially horizontal |
| strike slip fault | result of horizontal shear- mainly horizontal movement ex. San Andreas |
| seismic waves | vibration of the ground during an earthquake |
| p waves | primary waves- body wave- through earth's interior. squezze and pull rocks in the same direction the waves travel. push pull motion. fastest moving- first to arrive |
| s waves | secondary waves. cause rocks to move at right angles to the wave direction . side to side waves. second to arrive. only travel through solids. |
| surface waves | travel at surface. move up and down as they pass through rock at the surface and side to side. cause the most damage. last to arrive |
| seismometer | instrument that detects and records seismic waves. |
| seismogram | the record produced by a seismometer - usually paper |
| focus | the point underground where an earthquake originates usually several km's |
| epicenter | |
| travel time curves | - used to determine the distance from the epicenter to the seismic station. |
| magnitude | the amount of energy released during an earthquake |
| Richter scale | based on the size of the largest seismic waves generated by the earthquake. scale of 1- 10 |
| moment magnitude scale | takes into account the size of fault rupture, amount of movement and the rock stiffness. |
| modified mercalli scale | measure the amount of damage done by the earthquake |
| earthquake damages | 1. structures failure 2. land and soil failure 3. fault scarps 4. tsunami |
| mountain | spectacular feature of the earth's crust that lies above their surroundings |
| location of most mountains | |
| isostasy | |
| orogency | process that forms all mountain ranges. most orgenic belts near plate boundaries. convergent boundaries have greatest variety and tallest mountains |
| convergent boundary mountains | |
| divergent boundary mountains | ocean ridges are regions of magma upliifting. ocean ridge igneous rocks resemble a pile of sandbags called pillow basalts. |
| uplifted mountains | form as large regions of the earth have been slowly forced upward as a unit. can cause broad plateaus |
| fault block mountains | form when large pieces of crust are dropped downward between large faults |
| volcanic peaks | volcanoes that form over hot spots and are generally solitary peaks, far from tectonic plate boundaries |
| pillow basalts | billowy rocks that form when lava erupts onto the seafloor and quickly cools |
| lithosphere | crust in the upper mantle |
| convection currents | rising and falling in asthenosphere that move plates |
| trench | deepest part of ocean formed by subduction zones. * Marianas trench |
| isostasy | condition of equilibrium where by earths crust is balanced by the upward force of buoyancy and the downward force gravity |
Created by:
dk7
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