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Geological time

TermDefinition
Fossil The remains or impressions of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
Index Fossil a fossil that is useful for dating and correlating the strata in which it is found.
Permineralized remains Is a process of fossilization in which mineral deposits form internal casts of organisms.
Molds and Casts The "shell" of the organism is filled with various inorganic materials such as sediment or crystals; when the shell dissolves, it leaves an impression of the interior surface of the shells (e.g., muscle scars) on the material. A cast of the organism can t
Original Remains Fossils are formed when minerals in groundwater replace materials in bones and tissue, creating a replica in stone of the original organism or of their tracks.
Trace Fossils A fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.
Relative Ages Is an approximation and is deduced by the location of the strata in the overall structure, meaning the lower layers are older than the top layers.
Superposition Is a principle of quantum theory that describes a challenging concept about the nature and behavior of matter and forces at the sub-atomic level.
Horizontality states that layers of sediment are originally deposited horizontally under the action of gravity.
Absolute Age Is the true age of a rock or fossil. Absolute age tells scientists the number of years ago a rock layer formed.
Half-Life The time taken for the radioactivity of a specified isotope to fall to half its original value.
Isotopes Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element
Radioactive Decay The spontaneous transformation of an unstable atomic nucleus into a lighter one, in which radiation is released in the form of alpha particles, beta particles, gamma rays, and other particles.
Geologic Time Is a system of chronological measurement that relates stratigraphy to time, and is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships between events that have occurred throughout Earth's history.
Eon An indefinite and very long period of time, often a period exaggerated for humorous or rhetorical effect.
Era A long and distinct period of history with a particular feature or characteristic.
Period A length or portion of time.
Epoch A period of time in history or a person's life, typically one marked by notable events or particular characteristics.
Pangaea Is a hypothetical supercontinent that included all current land masses, believed to have been in existence before the continents broke apart during the Triassic and Jurassic Periods.
Trilobite An extinct marine arthropod that occurred abundantly during the Paleozoic era, with a carapace over the forepart, and a segmented hind part divided longitudinally into three lobes.
Precambrian Of, relating to, or denoting the earliest eon, preceding the Cambrian period and the Phanerozoic eon.
Mesozoic Era Includes the Triassic, Jurassic, and Cretaceous Periods and is characterized by the development of flying reptiles, birds, and flowering plants and by the appearance and extinction of dinosaurs. See Table at geologic time.
Cenozoic Era Is characterized by the formation of modern continents and the diversification of mammals and plants. Grasses also evolved during the Cenozoic.
Created by: 3108096
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