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10 Cards in this Set

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Precambrian Time

-plants(blue-green algae): more photosynthesis=more oxygen

-"Cambrian explosion": oceanic organisms appear at start of paleozoic era

Paleozoic Era

"Age of Invertebrates"

-ocean dwelling organisms

-atmospheric comp changed with evolving life forms

-life forms with shells, scales, bones

Mesozoic Era

"Age of Reptiles"


-cretaceous extinction (end of era)

-caused by large impact of meteor

Cenozoic Era

"Age of Mammals"

-present era

-mountain ranges

-dramatic changes in climate

Permian extinction

-end of Paleozoic

-96% of marine species & 8 out of 27 orders of insects

-caused by enormous volcanic eruptions

index fossils

fossils that occur only in rock layers of particular time period

cross-cutting relationship

fault or igneous intrusion is younger than the rock it cuts through above and below the unconformity

original horizontality

sedimentary rocks left undisturbed will remain in horizontal layer

laws of superposition

undeformed sedimentary rock layer is older than layers above it and younger than layers below it


current geological processes are the same processes that were at work in the past