Chapter C1: The Changing Earth

Lesson 1: What are the Earth’s layers? Lesson 2: How does the Earth’s crust move? Lesson 3: What changes the Earth’s surface? Lesson 4: How do rocks reveal changes on the Earth?

Lesson 4: How do rocks reveal changes on the Earth? Rocks change form. . . Weathered The series of changes that rocks go through is called the Rock Cycle. Eroded Heated Compressed Cemented Twisted Melted

Lesson 4: How do rocks reveal changes on the Earth? Igneous rocks. . . Form from melted mantle inside the Earth The mantle rises to the surface, cools, and hardens.

Lesson 4: How do rocks reveal changes on the Earth? Weathering. . . Breaks up the igneous rocks The tiny pieces of broken rock are called sand.

Lesson 4: How do rocks reveal changes on the Earth? Sedimentary rock. . . Forms when sand and sediments are pressed tightly and cemented together Sandstone and limestone are examples of this type of rock.

Lesson 4: How do rocks reveal changes on the Earth? Metamorphic rock. . . Forms when igneous or sedimentary rock is changed by extreme heat or pressure Marble is an example of this type of rock.

Lesson 4: How do rocks reveal changes on the Earth? Completing the cycle. . . Extreme heat and/or pressure inside the Earth can make metamorphic rock melt. This melted rock eventually makes its way back to the surface. When it cools, it forms igneous rock. Take a closer look!

Lesson 4: How do rocks reveal changes on the Earth? A little rearranging. . . When rocks change form, the atoms they are made up of rearrange into a different pattern. The strength of a rock depends on how its atoms are arranged. Some rocks are stronger than others.

Lesson 4: How do rocks reveal changes on the Earth? Compare and contrast. . . Minerals are arranged on a scale according to how hard they are. This is called the Mohs Hardness Scale. Smaller numbers on the scale = softer minerals. Larger numbers = harder minerals. Harder minerals will scratch softer minerals.

Mohs Hardness Scale

Lesson 4: How do rocks reveal changes on the Earth? Fossils form. . . Layers of sediments build up where they are deposited into a body of water. 2. Dead animals sink to the bottom and can become buried within the layers. 3. The layers form sedimentary rock, and the dead animal remains form fossils. 4. Fossils are exposed when the rock that contains them is weathered and eroded.

Scientists study these fossils to learn how the Earth has changed.

Lesson 4: How do rocks reveal changes on the Earth? What could these fossils tell? Shells at the top of a mountain. . . The area was once lower and under water. Fossilized trees on the bottom of a lake. . . The area was once dry. Warm-weather plant fossils in a frozen area. . . The area was once warmer.

Any Questions?