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| An unconformity in which the strata below dip at an angle different from that of the beds above. |
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| The concept that Earth was shaped by catastrophic events of a short-term nature. |
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| A span on the geologic time scale beginning about 65 million years ago following the Mesozoic Era |
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| Layers of rock that were deposited without interruption |
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| Establishing hte equivalence of rocks of similar age in different areas |
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| Principle of cross-cutting relationships |
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| A principle of relative dating. A rock or fault is younger than any rock or fault through which it cuts. |
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| A type of unconformity in which the beds above and belwo are parallel |
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| The largest division on the geologic calendar; eras are divided into shorter units called periods |
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| The remains or traces of organisms preserved from the geologic past |
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| Fossil organism that succeed one another in a definite and determinable order, and any time period can be recognized by its fossil content |
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| The division of Earth history int oblocks of time, eons, eras, periods, and epochs. The time scale was created using relative dating principles |
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| The time required for one half of the atoms of a radioactive substance to decay |
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| A piece of one rock unit contained within another. Inclusions are used in relative dating. The tock mass adjacent to the one containing the inclusion must have been there first in order to provide the fragment |
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| A fossil that is associated with a paticular span of geologic time. |
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| A span on the geologic time scale between the Paleozoic and the Cenozoic eras from about 248 million to 65 million years ago. |
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| An unconformity in which older metamorphic or intrusive ignous rocks are overlain by younger sedimentayr strata |
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Definition
| Date that specifies the actual number of years that have passed since an event occured. |
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| Layers of sediments are generally deposited in a horizontal or nearly horizontal position. |
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| A span on the geologic time scale between the eons of the Precambrain and Mesozoic era from about 540 million to 248 million years ago |
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| A basic unit of the geologic calendar that is a subdivision of an era. Periods may be divided into smaller units called epochs |
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Definition
| The part of geologic time represented by rrocks containing abudant fossil evidence. The eon extending from the end of the proerozoic eon (about 540 million years ago) to the present. |
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| All geologic time prior to the Paleozoic era. |
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Definition
| The spontaneous decay of certain unstable atomic nuclei |
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Definition
| The procedure of calculating the absolute ages o rocks and minerals that contain radioactive isotopes |
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| Rocks are placed in their proper sequence or order. Only the chronological order of events is determined. |
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| Young on top; Old on bottom |
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| A surface that represnts a break in the rock record, caused by erosion or nondeposition |
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| The concept that the processes that have shaped Earth in the geolofic past are essentially the same as those operating today |
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| The escape of gasses that had been dissolved in magma |
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Definition
| A large, relatively flat expandse of ancient metamorphic rock within the stable continental interior |
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Definition
| Structures that are deposited by algae and consist of layered mounds of calcium carbonate |
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