geologic dating

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• Dating methodologies in archaeology — Dating material drawn from the archaeological record can be made by a direct study of an artifact or may be deduced by association with materials found in the context the item is drawn from or inferred by its point of discovery in the sequence… …   Wikipedia

• dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …   Universalium

• Geologic time scale — This clock representation shows some of the major units of geological time and definitive events of Earth history. The Hadean eon represents the time before fossil record of life on Earth; its upper boundary is now regarded as 4.0 Ga.[1] Other… …   Wikipedia

• Geologic record — The layer cake like appearance of concordant strata laid down over hundreds of thousands of years …   Wikipedia

• geologic time — the succession of eras, periods, and epochs as considered in historical geology. [1860 65] * * * Interval of time occupied by the Earth s geologic history, extending from с 3. 9 billion years ago (corresponding to the age of the oldest known… …   Universalium

• Geologic timeline of Western North America — A timeline of significant geological events in the evolution of western North America. Dates are approximate.* 350 million years B.P. (Devonian) An unnamed terrane collides and accretes to the North American Plate, along a line roughly coinciding …   Wikipedia

• Timeline of the geologic history of the United States — This time line of the geologic history of the United States chronologically lists important events occurring within the present political boundaries of United States (including territories) before 12,000 years ago. This time line segment may… …   Wikipedia

• Radiometric dating — (often called radioactive dating) is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.[1]… …   Wikipedia

• helium dating — Method of dating that depends on the production of helium during the decay of radioactive isotopes of uranium and thorium. Because of this decay, the helium content of any mineral or rock capable of retaining helium will increase during the… …   Universalium

• Earth, geologic history of — Introduction       evolution of the continents, oceans, atmosphere, and biosphere. The layers of rock at the Earth s surface contain evidence of the evolutionary processes undergone by these components of the terrestrial environment during the… …   Universalium

• Lunar geologic timescale — The lunar geologic timescale (or selenologic timescale) divides the history of Earth s moon into five generally recognized geologic periods: the Copernican, Eratosthenian, Imbrian (upper and lower), Nectarian, and Pre Nectarian. The boundaries of …   Wikipedia