| Term | Definition |
|---|
| absolute dating | the process of establishing the age of an object by determining the number of years it has existed |
| isotopes | atoms of the same element hat have the same number of protons but different number of neutrons |
| radioactive decay | a process in which radioactive isotopes tend to break down into stable isotopes of the same or other elements |
| radiometric dating | a method of determining the absolute age of a sample cased on the ratio of parent material to daughter material |
| half-life | the time needed for half of a sample of a radioactive substance to undergo radioactive decay |
| parent isotope | an unstable radioactive isotope |
| daughter isotope | the stable isotope produced by the radioactive decay of the parent isotope |
| types of radiometric dating | Potassium-Argon, Uranium-Lead, Rubidium-Strontium, Carbon-14 |
| relative dating | any method of determining whether an event or object is older or younger than other events or objects |
| superposition | a principle that states that younger rocks lie above older rocks if the layers have not been disturbed |
| geologic column | an ideal arrangement of rock layers in which the oldest layer of rock is at the bottom |
| unconformity | a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time |
| disconformity | an unconformity that exists where part of a sequence of parallel rock layers is missing |
| nonconformity | an unconformity that exists where horizontal sedimentary rock layers lie on top of an eroded surface of older intrusive igneous or metamorphic rock |
| angular unconformity | an unconformity that exists between horizontal sedimentary rock layers and folded or tilted layers of rock |
| folding | the bending and buckling of rock layers from internal forces in the Earth |
| tilting | the slanting of rock layers from internal forces in the Earth |
| nondeposition | the stoppage of deposition when a supply of sediment is cut off |
| erosion | the process by which wind, water, ice, or gravity transports sediment from one location to another |
| intrusion | molten rock that squeezes into existing rock and cools |
| fossil | the remains or physical evidence of an organism preserved by geologic processes |
| petrifaction | a process in which minerals replace an organism's tissues |
| types of petrifaction | permineralization and replacement |
| permineralization | a process in which the pore space in an organism's hard tissue is filled up with mineral |
| replacement | a process in which the organism's tissues are completely replaced by minerals |
| trace fossil | any naturally preserved evidence of animal activity |
| types of trace fossils | tracks, burrows, and coprolite |
| coprolite | preserved animal dung |
| mold | a mark or cavity made in a sedimentary surface |
| cast | an object created when sediment fills a mold and becomes rock |
| index fossil | a fossil that is found in the rock layers of only one geologic age and is used to establish the age of the rock layers |
| examples of index fossils | ammonites and trilobites |
| eon | the largest division of geologic time |
| the four eons | Hadean, Archaen, Proterozoic, and Phanerozoic |
| era | a division of an eon |
| period | a division of an era |
| epoch | a division of a period |
| extinction | the death of every member of a species |
| the three eras | Paleozoic, Mesozoic, and Cenozoic |
| plate tectonics | the theory that the Earth's lithosphere is divided into tectonic plates that move around and change shape on top of the asthenosphere |
| convergent boundary | the boundary formed by the collision of two tectonic plates |
| divergent boundary | the boundary between two tectonic plates that are moving away from each other |
| transform boundary | the boundary between two tectonic plates that are sliding past each other horizontally |
| global positioning system (GPS) | a system of satellites that are used to measure the rate of tectonic plate movement |
| types of convergent boundaries | continental-continental, continental-oceanic, and oceanic-oceanic |
| ridge push | a process in which oceanic lithosphere slides downhill under the force of gravity |
| convection | hot rock rises and cooler rock sinks, separating the oceanic lithosphere |
| types of causes of tectonic plate motion | ridge push, convection, and slab pull |
| anticlines | upward-arching folds |
| synclines | downward, troughlike folds |
| monoclines | rock layers are folded so that both ends of the fold are horizontal |
| normal fault | the hanging wall moves down relative to the footwall |
| reverse fault | the hanging wall moves up relative to the footwall |
| strike-slip fault | opposing forces cause rock to break and move horizontally |
| most common types of mountains | folded, fault-block, and volcanic |
| rebound | the crust slowly springs back to its previous elevation |
| rift zones | sets of deep cracks that form between two tectonic plates creating a divergent boundary |
| crust | the thin and solid outermost layer of the Earth above the mantle |
| mantle | the layer of rock between the Earth's crust and core |
| core | the central part of the Earth below the mantle |
| chemical composition of the crust | oxygen, silicon, aluminum |
| chemical composition of the mantle | magnesium, aluminum, silicon |
| chemical composition of the core | iron, nickel |
| lithosphere | the solid, outer layer of the Earth that consists of the crust and the rigid upper part of the mantle |
| asthenosphere | the soft layer of the mantle on which the tectonic plates move |
| mesosphere | the strong, lower part of the mantle between the asthenosphere and the outer core |
| outer core | the liquid layer of the Earth's core |
| inner core | the solid, dense center of the Earth |
| tectonic plate | a piece of the lithosphere that moves around on top of the asthenosphere |
| seismic wave | a wave in the earth produced by an earthquake |
| continental drift | the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations |
| divisions of Pangaea | Laurasia and Gondwana |
| mid-ocean ridge | an underwater mountain chain that runs through Earth's ocean basins |
| sea-floor spreading | the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies |
| magnetic reversal | the change in the positions and polarity of Earth's magnetic poles |
| slab pull | the edge of a tectonic plate that contains oceanic lithosphere sinks and pulls the rest of the tectonic plate with it |
| compression | stress that occurs when forces act to squeeze an object |
| tension | stress that occurs when forces act to stretch an object |
| fault | the surface along which rocks break and slide past each other |
| folded mountain | rock layers are squeezed together and pushed upward |
| fault-block mountain | large blocks of the Earth's crust drops down relative to other blocks |
| rock | a naturally occurring solid mixture of one or more minerals or organic matter |
| rock cycle | the continual process by which new rock forms from old rock material |
| uses of rock | tools, buildings, monuments, roads |
| weathering | the process in which water, wind, ice, and heat break down rock |
| deposition | the process in which sediment moved by erosion is dropped and comes to rest |
| sedimentary rock | grains of sediment that are compacted and cemented together |
| metamorphic rock | rock that is formed when intense heat and pressure squeeze the sedimentary rock |
| igneous rock | rock that is formed when magma rises to higher levels of the Earth |
| sediment | grains of sand and clay as a result of the weathering of igneous rock |
| composition | the chemical makeup of a rock (minerals or other materials) |
| texture | the size, shape, and positions of the grains in a rock |
| uplift | the rising of regions of the Earth's crust to higher elevations |
| magma | the hot liquid that forms when rock partially or completely melts |
Combine with other sets
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