Term
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Definition
| Layers of rock stacked one atop the other like pages in a book. Oldest at the bottom, youngest at the top. |
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Term
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Definition
| The process of determining when something formed or happened in relation to other things. |
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Definition
| The process of determining when something formed or happened in exact units of time such as days, months, or years. |
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Term
| Law of Original Horizontaltality |
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Definition
| Sedimentary layers (strata) and lava flow were originally deposited as layered sheets, like the layers of a cake. If they are no longer horizontal or flat, it is because they have been displaced by subsequent movements of the Earth's crust. |
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Term
| Law of Lateral Continuity |
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Definition
| Lava flows and strata extend laterally in all directions until they thin to nothing or reach the edge of their basin of deposition. |
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Term
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Definition
| In and undisturbed sequence of strata or lava flows, the oldest layer is at the bottom and the youngest layer is at the top. |
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Term
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Definition
| Any piece of rock (clast) that has become included in another rock or body of sediment must be older than the rock or sediment into which it has been incorporated. |
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Term
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Definition
| A clast (a rock fragment, crystal, or fossil) is called an inclusion. |
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Term
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Definition
| The body of rock that surrounds the clast. |
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Term
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Definition
| Any feature that cuts across a rock or body of sediment must be younger than the rock or sediment that it cuts across. |
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Term
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Definition
| Surfaces called unconformites represent gaps in the geologic record that formed wherever layers were not deposited for a period time or else layers were eroded before the next layer could be deposited. |
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Term
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Definition
| an unconformity between to sets of strata that are parallel to one another. |
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Term
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Definition
| an unconformity between two sets of strata that are not parallel to one another. Forms when new horizontal layers cover up older layers folded by mountain-building processes and eroded down to nearly horizontal levels. |
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Term
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Definition
| an unconformity younger sedimentary rocks and subjacent metamorphic or igneous rocks. Forms when stratified sedimentary rocks or lava flow are deposited on eroded igneous or metamorphic rocks. |
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