Exam 3 review

Exam 3 review - Chapter 9 The Rock Record and Geologic Time...

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(sections from the book: all) Some key terms or ideas: relative dating- the study of the order things occurred. principle of original horizontality- sediments and lava flows are deposited horizontally therefore any deformation must occur after. principle of superposition- if undisturbed, from bottom to top, from old to young. principle of cross-cutting relationships- younger features cross cut older ones principle of fossil succession- as rock is weathered at different rates different eras are exposed at different times. index fossils- type of fossil used to identify a particular geologic time period inclusions- fragments included in an igneous rock are older than the host unconformity- a surface that represents a break in the rock record due to erosion or nondeposition. Disconformity- changes in the original form, shape, or size of a rock body Nonconformity- younger sedimentary or volcanic rocks overlay on plutonic or metamorphic rock. angular unconformity- separates overlying younger layers from eroded tilted or folded layers absolute dating (radiometric dating)- how long ago did a particular event happen stable isotope- retain all protons and neutrons unstable isotope- lose subatomic particles radioactive decay- spontaneous nuclear disintegration of isotopes with unstable nuclei half life- the time required for half of the original number of radioactive parent atoms to decay to stable daughter products. parent / daughter ratio- knowing the decay rate and amount of parent and daughter atoms in the sample, the age of the sample can be calculated. Precambrian-vast amount of time few fossils preserved. Phanerozoic- visible life
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Exam 3 review - Chapter 9 The Rock Record and Geologic Time...

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