1.3 Geological time Flashcards
in an undisturbed sequence of sedimentary rocks, younger layers overlie older layers, according to the principle of …
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summarise the development of geological time?
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dendrochronology involves dating of historic and geologic events through the study of …
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accurate radiometric dating is possible only if a rock contains a measurable amount of …
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what geologic principle is a direct result of gravity
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why is radiocarbon dating only rarely applied in geological work?
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within the world’s sedimentary rocks, fossils ….
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if the lithology and fossil content of 2 bodies of rock on opposite sides of a canyon are identical, then these remaining outcrops were likely physically connected at one time and formed part of an extensive, sheet like layer of rock. this idea summarises the principle of …
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magma has intruded into some limestone, and a marble rind framed surrounding the granite pluton. the marble rind must be younger than the limestone according to the principle of …
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if horizontal sedimentary strata overlie tilted strata (and no fault is present), the surface between the horizontal and tilted strata must be a(n) ________.
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If a basalt body cuts across a fault, what are the relative ages of the basalt and the fault?
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If the relative ages of two formations are known, what else about them can be inferred?
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Two atoms of a single element that differ in number of neutrons are said to represent two distinct ________ of that element.
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A radiometric age for a mineral crystal within an igneous rock measures the amount of time that has passed since the ________.
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Basaltic clasts within the basal layers of a conglomerate imply
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what geologic principle is not a result of gravity?
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James Hutton, the “father of geology,” put forth the principle of ________.
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When an unstable parent isotope decays
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The closure temperature represents the point when ________.
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what is the same for different isotopes of a single element?
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Numerical ages for boundaries between time units on the geologic time scale primarily resulted from the study of ________, in conjunction with relative age data.
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The principle of ________ explains the occurrence of older rock within a newer igneous body.
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The surface below sedimentary rocks that overlie igneous or metamorphic rocks is termed a(n) ________.
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If an igneous dike cuts across a sequence of sedimentary beds, ________.
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In the area immediately surrounding an igneous intrusion, a host limestone is locally metamorphosed to produce marble.
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Can the age of Earth be reliably estimated from sediment thicknesses?
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If a sandstone lies on top of a shale, ________.
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Magnetostratigraphy takes advantage of the fact that Earth’s magnetic field ________.
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Basaltic clasts within a conglomerate have been radiometrically dated to 50 million years ago. Is this a reliable age for the conglomerate?
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Which method of correlation is most reliable for determining age equivalence among bodies of rock that are physically separated by vast distances?
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Uniformitarianism is succinctly summarized by which phrase?
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If all of Earth’s history were compressed into a single year, Homo sapiens would first appear on ________.
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Which eon of geologic time is represented by rocks containing abundant shelly fossils?
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Buried erosional surfaces between parallel sedimentary strata are termed ________.
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Relative ages expressed on the geologic time scale primarily resulted from the study of ________.
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As understood by modern geologists, the principle of uniformitarianism implies that ________.
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Radiometric dates applied to sedimentary rocks produce ages that ________.
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Concerning the relative ages of the granite and sandstone, ________.
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After one half-life has passed, what is the ratio of parent isotopes to daughter isotopes?
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Seasonal changes create layering in glaciers known as ________.
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How much of a radioactive parent isotope will remain after three half-lives have passed?
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In an unweathered sample of rock, the ratio of an unstable isotope to its stable daughter isotope is 1:15. If no daughters were present at the time the rock cooled below closure temperature, and the half-life of the isotope is 50 million years, how old is the rock?
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How is the half-life of a radioactive parent isotope defined?
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