Earth AdventureEarth AdventureEarth AdventureEarth Adventure

This slide show will enable students to unravel a modern mystery as they learn about the dynamic processes that have shaped our planet…

This slide show will enable students to unravel a modern mystery as they learn about the dynamic processes that have shaped our planet…

Mountains From the Sea…Mountains From the Sea…• Early in this century an extraordinary fossil

discovery was made high in the Canadian Rockies. A geologists’ packhorse stepped on a loose piece of black shale and turned it over.

Embedded there underneath were the fossilized remains of creatures from the sea.

Mountains From the Sea…Mountains From the Sea…

Some scientists reasoned they were leftovers from a time when the seas were much higher…

Others asserted that the fossils were “stacked” in layers of sediment deposits that correspond to earlier and earlier time periods…

What do you think?

Mountains From the Sea…Mountains From the Sea…

• Go to chapter 9 and write a short answer to the challenge of the fossils based on evidence you see in the text. Please include two pictures that might explain how mountains may rise from the sea.

Mountains From the Sea…Mountains From the Sea…• As you have probably already realized, mountains form

when TECTONIC PLATES collide and buckle upwards.• But why are these plates moving across the crust of the

earth in the first place?• In addition, you also know that mountains may form

because of volcanic activity. Is that why we find seashells in the mountains?

Two theories may help you find the answer!

Continental Drift and Internal Heat and Pressure

Continental DriftContinental Drift• The theory that the plates of the earth are floating on a

dense, molten, magnetic fluid of rock and metals (basically HOT LAVA!).

• If this were true, then the density of the tectonic plates and the density of the “lava” must be different.

• What elements might the “lava” contain? One of the potential tragedies of continental drift.

Continental DriftContinental Drift

• More evidence of continental drift theory is available at this great link from the Exploratorium in San Francisco…

The continent of Pangaea

Internal Internal Heat and Heat and PressurePressure

The picture on the The picture on the right is a diagram of right is a diagram of

the inside of a the inside of a volcano. Use your volcano. Use your

text to find the text to find the names of the names of the

numbered regions.numbered regions.

Internal Heat and PressureInternal Heat and Pressure

Radioactive substances are the primary source of heating the core to temperatures in excess of 4000oC!

Molten rock is like wax…it is a fluid when hot and very brittle when cool…

So HOW could this explain the dynamic changes of the Earth’s crust?

VolcanoQuicktime movie courtesy of:http://www.sci.sdsu.edu/volcano/

In order to understand the entire lifespan of a rock, you need to see an example of how rocks are recycled to create new “crust.”

Notice how mountains get reduced by weathering and created by heat and pressure.

Mountains From the Sea…Mountains From the Sea…

• The sand and rocks that tumble down rivers eventually settle to the bottom of the ocean and trap living tissue into a permanent time capsule.

• The effects of erosion over time will contribute to the layers of sediment that trap organisms year after year.

• If the conditions are right, the organism will not decay and disappear. Instead, it will “fossilize” into its mineral casing and wait to be discovered.

Quiz Question: Which factor, continental drift or internal heat and pressure, creates this type of change in the crust? (Pressure at Arrow)

Quiz Question: Which factor, continental drift or internal heat and pressure, creates this type of change in the crust? (Pressure at Arrow)

Mountains From the Sea…Mountains From the Sea…

In conclusion, students should be able to explain how the the crust of the earth is shaped by the two factors of CONTINENTAL DRIFT and INTERNAL HEAT and PRESSURE.