Fossils
By:Madison Pugh
Mold fossil Forms when sediments bury an organism decays leaving a cavity in the shape of the organism.
Cast fossil Forms when a mold is filled with sand or mud that hardens into the shape of the organism.
Petrified fossil Forms when minerals soak into the buried remains, replacing the remains, and changing them into rock.
Preserved fossil Forms when entire organism or parts of organism are prevented from decaying by being trapped in rock,ice,tar, or amber.
Carbonized fossil Forms when organisms or parts,like leaves,stems,flowers,fish, are pressed between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving the carbon imprint in the rock.
Trace fossil Forms when the mud or sand hardens to the stone where a a footprint,trail, or burrow of an organism was left behind.
Index fossil Fossil that defines and identifies geologic periods; often in only one layer of rock. ● Easily recognizable ● Short-lived (found only in a few layers of rock worldwide) ● Wide distribution (geographic range) ● the organism must be unique.
Ammonite fossil Ammonite fossils are found worldwide, but they existed for only a very specific period of time.This means ammonites are found in very specific layers of rock.when an index fossil is found, the age of the rocks it is preserved can be determined.
Summary There are different types of fossils and they all tell us about our past and what has/have walked on this earth before us. Also that they are a big part of history.
Credit Mr.Davis sildeshow