How Earth’s Past is Revealed.. Evidence of prehistoric life Traces or remains of living things from long ago Give important clues about Earth’s.

FOSSILSHow Earth’s Past is Revealed.

FOSSILSEvidence of prehistoric lifeTraces or remains of living things from long ago

Give important clues about Earth’s past

TYPES OF FOSSILSMost fossils are hardened animal remains such as shells, bones, and teeth

Minerals replace the remains Fossils leave impressions in rock Soft parts of organisms can be preserved in ice, amber, or tar

FOSSIL FORMATIONConditions have to be just rightRemains need to be preserved before decomposition

Preserved soft parts are more rare than hard parts

Most fossils form in Sedimentary Rock As the sediment settles and forms layers, plant and animal remains can be preserved

Why would you not find fossils in Igneous Rock?

FOSSILS IN ROCKMold – a visible shape of an organisms remains left after it decays (like a shoe print in the sand)

Cast –a solid model in the shape of the organisms remains (if the shoe print was filled in with clay and it hardens into the shape of the shoeprint)

FOSSILS IN ROCKS

Petrified Wood –minerals take the place of the cells and harden over time making the organism look like it turned to stone

Carbon Films –carbon can be found in every living thing, sometimes the carbon is the only thing left behind after the organism decays, can show details of soft parts missed in other types of fossils

FOSSILS IN ROCKSTrace Fossils –evidence of an organisms presence in a location, not remains

FootprintsTrailsAnimal holesFeces (yes, this is poo!)

ICE CORESA tubular sample that shows the layers of snow and ice that have built up over thousands of years

Found in glaciers and the polar ice capsScientist analyze trapped air

Looks like bubbles in the ice Can tell us about the atmosphere thousands of years ago

Dust or ash in the ice means volcanic eruptions Ice layer thickness tells us about temperatures

INDEX FOSSILSFossil Record – all the fossils that have been found since the study of fossils began

Index Fossils Fossils that are unique to a specific time period

Remains of organisms that lived for a short period of time

Used to date rocks and other fossils

QUICK CHECK1. What type of rock will you most likely find fossils?

A. IgneousB. MetamorphicC. SedimentaryD. Intrusive

2. Which part of an ancient reptile would you expect to see in a rock fossil?

A. eye

B. bone

C. heart

D. muscle

3.Which type of fossil would be most likely to show the complete outline of a leaf?

A. petrified wood

B. cast fossil

C. mold fossil

D. carbon film

4. Which type of fossil is used to help date the rocks and fossils found around it?

A. index

B. cast

C. mold

D. trace

5. What do scientist study in ice cores to know about ancient atmospheric conditions?

A. pollen

B. dust

C. ash

D. air bubbles