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Chapter 13
Clues to Earth's Past
Question | Answer |
---|---|
permineralized remains | fossils in which the spaces inside are filled with minerals from groundwater |
carbon film | thin film of carbon residue preserved as a fossil |
mold | a type of body fossil that forms in rock when an organism with hard parts is buried, decays, or dissolves, and leaves a cavity in the rock. |
cast | a type of body fossil that forms when cystals fill a mold or sediments wash into a mold and harden into rock |
index fossil | remains of species that existed on Earth for a relatively short period of time, were abundant and widespread geographically, and can be used by geoloists to assign the ages of rock layers |
principle of superposition | states that in undisturbed rock layers, the oldest rocks are on the bottom and the rocks become progressively younger toward the top. |
fossil | remains, imprints, or traces of prehistoric organisms that can tell when and where organisms once lived and how they lived |
relative age | the age of something compared with other things |
unconformity | gap in the rock layer that is due to erosion or periods without any deposition |
absolute age | age, in years, of a rock or other object; can be determined by using properties of the atoms that make up materials |
radioactive decay | process in which some isotopes break down into other isotopes and particles |
half-life | time it takes for half the atoms of an isotope to decay |
radiometric dating | process used to calculate the absolute age of rock by measuring the ratio of parent isotope to daughter product in a mineral and knowing the half-life of the parent |
uniformitarianism | principle stating that Earth processes occurring today are similiar to those that occurred in the past |