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15 Cards in this Set
- Front
- Back
what is a fault and how does it effect age of rocks?
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formed when plates slide past eachother
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how old is the earth?
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4.6 billion years old
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how do fossils form?
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an organism is traped under mud or some other substance and is preserved
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what parts of organisms make good fossils?
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bones&teeth
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what is a trace fossil?
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a trace of something
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what is an index fossil?
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a fossil that helps detirmine age of rocks
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what is geological and biological change?
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geological-when the earth changes;biological-when living things change
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what are the 4 eras and age of them?
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precambrian-450my
paleozoic-550-250my mesozoic-250-65my cenozoic-65my-present |
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what is the birth of earth cycle?
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-spining cloud of gas&dust
-gravity causes clumping -meteor hits,causes crust to melt -meteors&volcanos give off gas -atmo. forms -clouds block sun -rains for 1000's of years;earth cools -oceansµcontinents form |
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what are the divisions of time in order from longest to shortest?
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eons,eras,periods,epochs
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what era did continents form and break up?
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precambrian(forms)paleozoic(break)paleozoic(forms)meso(break)ceno(form)
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what were the major organisms of each era?
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precambrian-microorganism
paleozoic-fish mesozoic-reptiles cenozoic-mammals |
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examples of index fossils
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horses, horseshoe-crab thing
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why do we study fossils?
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so we can learn about the organisms from our past
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why do we know alot/little about an era?
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we know alot b/c we found alot of fossils and other info. we know little b/c we didn't find alot of fossils
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