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Rocks

Sedimentary Rocks - Fossils.

Fossils are only found in sedimentary rocks.
Fossils are formed from the remains of plants or animals which have died
and become buried in sediments before they could decay.

Over a long period of time,
the original plants or animals are slowly replaced by minerals.
Eventually, all the material is replaced,
leaving a rock which is a copy of the original plant or animal.
Fossils are themselves rocks!

If fossils of the same age are found in different rocks,
then this is good evidence that these rocks are of the same age.
This is a useful way of identifying sedimentary rock ages.

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