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FINAL2:Geologic Time

8th Grade Earth Science FINAL 2

QuestionAnswer
How do permineralized fossils form? -Organism dies near water. Organism gets covered by sediment, protecting from being destroyed and slowing decomposition. - Soft parts decay, minerals mix w/ water and seeps into pores in bones & crystallize. Surrounding sediment is now rock.
How do you determine the relative age of a fossil/rock using the layers of rock? - If a vein of rock cuts across layers of rock, then the vein of rock is younger than the surrounding rock because the surrounding rock had to already have been there for it to cut across. - Principle of Superposition: newest layers ontop oldest layers
How do you determine the absolute age of a fossil/rock using half-life? The time it takes for HALF of the unstable atoms in a sample to decay is called the isotope's Half-Life. The amount of unstable atoms in the sample continues to half itself until the amount is unmeasureable (can't half half of an atom).
How does natural selection work (related to organic evolution)? Organisms that can not adapt physically or genetically will not survive... A process by which organisms with characteristics that are BEST suited to a certain environment have a better chance of surviving & reproducing.
What are the three eras of the current (Phanerozoic) eon? (order of oldest to current) Paleozoic, Mesozoic, Cenozoic
Which era ended with the largest mass extinction in Earth’s history? Paleozoic
What factors/event led to the extinction of the dinosaurs? Plate Tectonics causing climate changes, Comet/Asteroid hit the Earth, Blocking out of the Sun, Cooling temperatures, Starvation
What was Oklahoma’s environment like during the Paleozoic era? Under a large sea
Created by: *BROOKE*
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