history of earth: using fossils and rock layers to tell the story

Exploration of Earth History

What evidence can we find in rocks?

Rocks tell the story of Earth’s History

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Red Rock Canyon CODevil’s Tower

Wyoming

Painted Desert Arizona

Rocks tell the story

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Rocks can provide evidence

Age of the Earth Type of organisms Evolution of Species

Environmental Changes

Original RemainsFossils that are the actual bodies or body parts

Who is ICE MAN?

Who needs Ice if you have Maverick?

Ice Man from Himalayans

5,300-year-old corpse turned up on the mountain border between Austria and Italy in 1991

Ice Man Trapped

Ice Man Close Up

Inferences from NatGeo

Trapped in Amber

Tar Pits

Fossils in Sedimentary Rocks

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Mold: hollow area left by the living thing

Cast: solid mineral deposit that filled the mold, leaving a copy

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Trace Fossils

Trace: tracks, burrows, nests

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Petrification tissue replaced by minerals

Carbon Films

Ice Core Samples

Relative Dating How old something is in comparison

to something else

Index Fossils

Only around

for short periods of time

Ammonite Found in sedimentary rock

layersabout 400 million years ago

Trilobite Fossils show:BiodiversityHow species have changed over timeCorrelation between rock layers from

around the worldRelative ages to particular strataEvidence for the geological time scale

Law of SuperpositionLaw that states the older layers were laid down

first, then younger materials was put down on top of it

Younger Igneous Rock can cut through rock layers

Closer Look at Rock Layers

Do you see evidence of Erosion

Earthquake A river

Principles of Crosscutting

The geologic feature which cuts another is

the younger of the two features

What kind of rocks are these fossils in?

Which layer is oldest?

Which layer is youngest?

How do you know?

Intrusions vs Extrusions

Intrusion: when magma cools within the earth

Always younger than the rock around it

Extrusion: when lava cools outside the earth

Image A Image B

Image C

Is this an Igneous Intrusion?

What evidence do we see in these

Road Cuts?

Image A Image B Image C Image AImage AImage A

Image D Image E Image F

Did the fold happen before the red rock was deposited?

What could have caused F? When did it happen?

Did the eruption happen before or after layer H?

What story does these rocks tell?Where is the river?

Between which two layers was a fast moving river?

Absolute Dating

The actual age of the event

Half Life: the length of time it takes for half of the atoms in a sample of a radioactive element to

change from an unstable form into another form