1. Rocks and Fossils

2. Learning about ROCKS Rocks are all around us.
Scientists who study rocks are known as geologists.
Geologists examine rocks to learn about the earth.
Sedimentary rocks are the most common.
They form in layers. [Example 1] [Example 2]

3. Fossils
Sometimes geologists find fossils in rocks and between layers of rocks.
Fossils of plants and animals, along with rock layers, help geologists learn about the past.

4. Fossil Formation Example From http://www. rom. on
Snail lives in the ocean.
Snail dies.

5. Fossil Formation Example From http://www. rom. on
Dead snail is buried by sand and sediments.
The soft body of the snail decays as the hard body is buried.

6. Fossil Formation Example From http://www. rom. on
Millions of years later, the sand and sediments harden into rock and the shell is preserved as a fossil.
But if fossils are buried, how do we know about them?

7. Chalk Talk Chalk can help us answer the question.
What happens to chalk if your teacher uses it to write on the chalkboard day after day?
It wears away slowly.
This wearing away is called weathering.
Erosion carries weathered rock away
Water, wind and ice cause erosion.

8. Did you know…? All rocks can be weathered and eroded.
As layers of rock are weathered or eroded, fossils appear.
Mountains don’t grow up over time—they shrink. Any idea why?

9. Study Question
As part of a school project, you place a rock weighing exactly 2 kg (kilograms) at the top of a hill.
After 10 years, no person has touched the rock. What would you expect the rock to weigh—more than 2 kg, exactly 2 kg, or less than 2 kg? Give a reason for your answer.

10. Appalachian Mountains

11. Grand Canyon