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What type of rock most commonly preserves fossils
sedimentary
What is an index fossil
a fossil that lived a short time but was widespread
As radioactive elements decay, they produce what
daughter isotopes
The age of a rock layer containing an index fossil can be determined by what
comparing to other fossils
What does the half-life of a radioactive element tell us?
how long it takes half the atoms to decay
A fossil is defined as ....
preserved evidence of past life
What does relative dating tell us
THat one rock is older or younger than the other
In Virginia, which provinces contain the most fossils
Coastal Plain and Appalachian Plateau
What is a cross-section diagram used for?
to show sequence events from oldest to youngest
What are marine fossils commonly preserved in?
sedimentary rock
Which type of fossil preservation involves an impression left in a rock
mold
What does absolute dating use
radioactive decay of elements
What kind of fossils are Virginian mostly
marine
What are cross-cutting relationships a help in?
relative dating
Radiometric dating is most useful for dating what
igneous rocks and their minerals
What is the law that states younger rocks are on top of older rocks
superposition
which dating method assigns numerical ages
absolute dating
what does finding marine fossils in Virginia suggest?
It was once underwater
What are three causes of mass extinction?
volcanoes, asteroid impacts, and continental collisions
What does studying fossils and rock types help scientists understand
evolution of Earth's conditions over time
younger features cut across older rocks
what is a parent isotope
the original radioactive element
Which geologic time eras are represented by Virginia fossils?
Paleozoic, Mesozoic and Cenozoic
When does a cast fossil form?
when minerals fill a mold
PLease loudly make the sound of your favorite animal
answers will vary