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15 Cards in this Set

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  • Back
what is a fault and how does it effect age of rocks?
formed when plates slide past eachother
how old is the earth?
4.6 billion years old
how do fossils form?
an organism is traped under mud or some other substance and is preserved
what parts of organisms make good fossils?
bones&teeth
what is a trace fossil?
a trace of something
what is an index fossil?
a fossil that helps detirmine age of rocks
what is geological and biological change?
geological-when the earth changes;biological-when living things change
what are the 4 eras and age of them?
precambrian-450my
paleozoic-550-250my
mesozoic-250-65my
cenozoic-65my-present
what is the birth of earth cycle?
-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
-oceans&microcontinents form
what are the divisions of time in order from longest to shortest?
eons,eras,periods,epochs
what era did continents form and break up?
precambrian(forms)paleozoic(break)paleozoic(forms)meso(break)ceno(form)
what were the major organisms of each era?
precambrian-microorganism
paleozoic-fish
mesozoic-reptiles
cenozoic-mammals
examples of index fossils
horses, horseshoe-crab thing
why do we study fossils?
so we can learn about the organisms from our past
why do we know alot/little about an era?
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