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Definition
| an absolute dating method for organic remains such as bone or shell, in which the amount of change in the amino acid structure is measured |
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Definition
| a relative dating method that uses the associations of fossils in strata to determine each layer's approximate age |
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| plants that take in carbon through C3 photosynthesis, which changes carbon dioxide into a compound having three carbon atoms. Tending to be from more temperate regions these plants include wheat, sugar beets, peas, and a range of hardwood trees |
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Definition
| plants that take in carbon C4 photosynthesis, which changes carbon dioxide into a compound with four carbon atoms. These plants tend to be from warmer regions with low humidity and include corn, sugarcane, millet, and prickly pear. |
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| the era lasting from 65 mya until the present, encompassing the radiation and proliferation of mammals such as humans and other primates |
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| dating methods that use predictable chemical changes that occur over time |
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Definition
| relative dating methods that are based on material remains' time spans |
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Definition
| a chronometric dating method that uses a tree-ring count to determine numerical age |
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| electron spin resonance dating |
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Definition
| an absolute dating method that uses microwave spectroscopy to measure electron's spins in variations materials |
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Definition
| divisions of periods (which are the major divisions of eras) in geologic time |
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| major divisions of geologic time that are divided into periods and further subdivided into epochs |
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Definition
| an absolute dating method based on the measurement of the number of tracks left by the decay of uranium-238 |
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Definition
| a relative (chemical) dating method that compares the accumulation of fluorine in animal and human bones from the same site |
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Definition
| marine protozoans that have variably shaped shells with small holes |
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Definition
| the time it takes for half of the radioisotopes in a substance to decay; used in various radiometric dating methods |
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Definition
| rock formed from the crystallization of molten magma, which contains the radioisotope 40K; used in potassium-argon dating |
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Definition
| fossils that are from specified time ranges are found in multiple locations, and can be used to determine the age of associated strata |
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Definition
| two or more forms of a chemical element that vary in the number of neutrons in the nucleus and by the atomic weight |
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Definition
| the second major era of geologic time, 230-65 mya, characterized by the emergence and extinction of dinosaurs |
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Definition
| an absolute dating method based on the reversals of Earth's magnetic fields |
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Definition
| the first major era of geologic time, 570-230 mya, during which fish, reptiles, and insects first appeared |
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Definition
| a hypothetical landmass in which all the continents were joined, approximately 300-200 mya |
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Definition
| the earliest stone tools, in which simple flakes were knocked off to produce an edge used for cutting and scraping |
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Definition
| a kind of light used in amino acid dating because it allows amino acid changes to be observed and measured |
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Term
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Definition
| the chemical reactiong resulting in the conversion of L amino acids to D amino acids for amino acid dating |
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Definition
| the radiometric dating method in which the ratio of 14C to 12C is measured to provide an absolute date for a material younger than 50,000 years |
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Definition
| the radiometric dating method in which the ratio of 40K to 40Ar is measured to provide an absolute date for a material older than 200,000 years |
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Definition
| rock formed when the deposition of sediments creates distinct layers, or strata |
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Term
| Steno's law of superposition |
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Definition
| the principle that the lower the stratum or layer, the older its age; the oldest layers are at the bottom, and the youngest age at the top |
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Definition
| layers of rock, representing various periods of deposition |
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Term
| stratigraphic correlation |
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Definition
| the process of matching up strata from several sites through the analysis of chemical, physical, and other properties |
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Definition
| the study of the deposition of plant or animal remains and the environmental conditions affecting their preservation |
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Definition
| refers to various structures on Earth's surface, such as the continental plates |
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Term
| thermoluminescence dating |
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Definition
| a relative dating method method in which the energy trapped in a material is measured when the object is heated |
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