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| Using various radioactive decay dating techniques to assign ages in years before the present to rocks |
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| An uncomformity below which older rocks dip at a different angle (usually steeper) than overlying strata. |
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| An association of sedimentary rocks defined its fossil content. |
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| An association of sedimentary rocks defined its fossil content. |
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| Carbon 14 dating technique |
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| Absolute dating technique relying on the ratio of C14 to C12 in an organic substance, useful back to about 70,000 years ago. |
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| Demonstration of the physical continuity of rock units or biostratigraphic units, or demonstration of time equivalence as in time-stratigraphic correlation. |
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| A boundary across which seismic wave velocity or direction of travel changes abruptly, such as the mantle-core boudary. |
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| The absolute dating proccess in which small linear tracks (fission tracks) resulting from alpha decay are counted in mineral crystals. |
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| An easily identifiable fossil with an extensive geographic distribution and short geologic range useful for determining the relative ages of rocks in different areas. |
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| The time neccessary for half of the original number of radioactive atoms of an element to decay to a stable daughter product; for example, the half-life for potassium 40 is 1.3 billion yrs. |
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| A body of rock, such as a formation, defined solely by its physical attributes. |
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| An unfconformity in which stratified sedimentary rocks overlie an erosion surface cut into igneous or metamorphic rocks. |
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| Principle of cross-cutting relationships |
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| A principle holding that an igneous intrusion or fault must be younger than the rocks it intrudes or cuts across. |
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| Principle of fossil succession |
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| A principle holding that fossils and especially groups or assemblages of fossils, succeed one another through time in a regular and predictable order. |
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| A principle holding that inclusions or fragmentsin a rock unit are older than the rock unit itself; for example,granite inclusions in sandstone are older than the standstone |
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| principle of lateral continuity |
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| A principle holding that rock layers extend outward in all directions until they terminate |
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| The planets orbit the sun. The Geo-centric theory vs. Hylio centric theory We are the center of the earth, everything went around us. |
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| Planets revolve around the earth 1st and 2nd law of motion - body in motion stays in motion, body in rest stays at rest; strength of materials |
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| The universe never has a beginning nor end; scienctific method; water cycle |
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| Law of; Superposition, original horizontality, lateral continuity |
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| Cross-cutting Relationships, uniformatarianism |
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| Determined earth's age by meltingan iron ball-75,000 yrs |
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| All rocks owe their origins to the oceans; Neptunism |
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| Principle of original horizontality |
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Definition
| according to this principle, sediments are deposited in horizontal or nearly horizontal layers. |
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| Principle of Superposition |
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| a principle holding that in a vertical sequence of undeformed sedimentary rocks, the relative ages of the rocks can be determinded by their position in sequence-oldest at the bottom followed by successively younger layers. |
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| Principle of uniformitarianism |
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| A principle holding that we can interpret past events by understanding present day processes, based on the idea that natural processes have always operated in the same way. |
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| The spontaneous change of an atom to an atom of a different element by emission of a particle from its nucleus (alpha and beta decay) or by election capture |
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| The process of determining the age of an event; involves placing geologic events in their correct chronological order but does not involve consideration of when the events occurred in number of years ago. |
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| A body of strata that was deposited during a specific interval of geologic time; for example, the Devonian system was deposited during the Devonian period |
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| Any of the units such as eon, era, period, epoch, and age used to refer to specific intervals of geologic time. |
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| The process of determining the age of a tree or wood in a structure by counting the number of annual growth rings. |
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| A break in the geologic record represented by an erosional surface seperating younger strata from older rocks. |
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