GEOL- Final Study Guide - GEOL Final Study Guide Chapter 9:...

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GEOL Final Study Guide Chapter 9: Relative dating – Relative dating is the science of determining the relative order of past events, without necessarily determining their absolute age. Nonconformity – An unconformity in which the older rocks below the unconformity are not layered Numeric dating – The process of determining ages of rocks by using analytical measurements (aka Absolute Dating) Half-life – In radioactive decay refers to the time it takes for half of the parent atoms to decay into a daughter product Original horizontality – The principle that most sediments and many volcanic units are deposited in layers that originally are more or less horizontal Isotopic dating – The process of dating rocks using radioactive decay Principle of superposition – The concept that a sedimentary or volcanic layer is younger than any rock unit on which it is deposited Isotope – One of two or more species of the chemical element but differing from one another by having a different number of neutrons Cross-cutting relations – The principle that a geologic unit or feature is older than a rock or feature that cross cuts it Cenozoic Era – A major subdivision of geologic time from 65mya to the present; characterized by an abundance of mammals Inclusions – A fragment of older rock or material that is contained within another rock or material, as in a fragment of preexisting rock in magma Mesozoic Era – A major subdivision of geologic time from 251 mya to 65 mya; characterized by dinosaurs Contact effects – Evidence of baking, passage of hot fluids, or some other manifestation of the thermal and chemical effects of a magma chamber or a hot volcanic unit, as expressed in changes to adjacent wall rocks Paleozoic Era – A major subdivision of geologic time, beginning at the end of the Precambrian; from 542 to 251 mya Angular unconformity – An unconformity in which the older, underlying strata dip more steeply or at a different angle than the younger, overlying strata Precambrian – A very long interval of geologic time, from the formation of the solid earth to the beginning of the Paleozoic Disconformity – An unconformity in which the bedding planes above and below the break are essentially parallel, but recording erosion or some other interruption in the deposition of layers Fossil – Any remains, trace, or imprint of a plant or animal that has been preserved from some past geologic or prehistoric time 1. What evidence is there that the earth is old other than isotopic dating (re. page 252, section B)? Tree Rings – record annual growth cycles; pine trees from the American West can be correlated from living tress to form a continuous record back to 9,000 years ago Ice Cores – Cylinders of ice drilled from ice sheets in Greenland and Antarctica contain thin layers produced by yearly cycles of the seasons. Can represent from 10s of thousands of years to 100,000 years. Varves
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GEOL- Final Study Guide - GEOL Final Study Guide Chapter 9:...

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