1. Our Earth
Grade 4
Mrs. Hansen

2. Chapter 8 – Minerals & Rocks
Minerals – are natural, nonliving solid crystals that make up rocks
Earth’s crust is made of rocks
Rocks are made of minerals

3. Can you name the different layers? Which layer do we walk on?
Minerals
Have crystals
Each mineral has the
same chemical makeup
3,000 types of minerals
“rock forming” minerals are
the only minerals
that make up rocks
Rocks
3 Types of Sedimentary Rocks
Mudstone, sandstone and limestone
Igneous rocks – form from molten rock
Metamorphic rocks – have changed because of heat and pressure
Our Earth
Layers of our earth
Can you name the different layers?
Which layer do we walk on?

4. Name some Minerals Granite – one of the most common rocks
Quartz is hard and glassy
Mica – form rocks that are usually brown or black
Feldspar is often white or pink

5. How do we know it is a Mineral?
To identify a mineral scientists look at “Physical Properties” how it looks
Color – certain minerals show a certain color
Luster – how the mineral reflects light (is it dull, metallic, pearly, glassy or silky)
Streak – scratch the mineral on a surface – what color of powder does it leave behind
Mohs Scale – How hard is the mineral on a scale from 1 – 10 (how easy can it (the mineral be scratched) turn to page 241 in your book.

6. Rocks
Sediment – eroded material (rocks, fossils, dead plants, shells and animal matter wash down to rivers, lakes and oceans through erosion. This material that settles to the bottom is called sediment.
Sedimentary rocks are sediment that has stuck together and harden.

7. Can Rocks turn into soil?
Yes! Over time weathering can cause rocks to loosen and break apart.
Weathering is the breaking up of rock, caused by exposure to natural forces present at the Earth’s surface, such as water through freezing and heating, water run off and plant roots breaking through a weakened rock.

8. How do we control weathering?
Building jetties to strengthen land that is near the water
Building dams to hold back water
Plowing fields in the opposite direction the wind blows.
Creating terraces with rocks or other materials to slow down the flow of water
Planting grasses, trees and other plants to prevent soil from washing away.

9. What do you think?
As our class walks to the cafeteria we notice that the sidewalk has small holes and is bumpy. What do you think has caused this?
Wind
Chemicals
Deposition
weathering

10. Weathering
Weathering is when forces of nature break down rocks through water, ice, temperature changes chemicals or living things such as plants that cause weathering.
Wind erosion is when the wind blows the soil
Chemical weathering is when chemicals cause rocks to change into different materials. For example rain water mixes with Carbon dioxide (CO2) in the air to form a weak acid. This is called “acid rain”

11. Is weathering the only thing that will change rocks?No
Erosion is when water, ice, gravity, and wind often work together to move weathered pieces of rock.

12. How fossil forms
Turn to page 244 look at the pictures of the dinosaur and how it can become part of sedimentary rock
Fossils help scientists form hypothesis.
How?

13. Fossils tell a story
Looking at the fossils in the rock layers tell scientists how old the layers of rock are.
Examples – ammonoids, sea creatures that looked like snails are estimated to have lived only from about 408 to 66 million years ago. An ammonoid fossil found in a layer of rock means the layer formed between 408 and 66 million years ago.

14. Geologic (means rock)
Scientists have divided their estimates of Earth’s history into periods of time.
The periods are put into a geologic (rock) time scale.
Earliest (means oldest) period is at the bottom.
Turn to page 245 and look at the scale and captions at the right of the page.

15. Igneous and Metamorphic Rocks
Igneous rocks – form from molten rock, the word igneous means fire
A layer of rock below earth’s crust is so hot that it is partially melted.
Igneous rocks may form above or below earth’s surface.

16. 2 ways Igneous Rocks form
Volcanoes where the molten rock can ooze out like a red hot river and explode out in hot globs
Magma slowly rising toward the earth’s surface (this is the most common). The magma rises and fills in cracks and melts the surrounding rock or forces it aside to make space, it cools. It can take more than a MILLION years for this to happen.
Turn to page 248 on the left side

17. Metamorphic Rocks
Natural forces cause rocks to change form COMPLETELY. These rocks change because of heat and pressure.
Metamorphic rocks can be sedimentary, igneous and other metamorphic rocks.
Example Limestone (a sedimentary rock) can turn into marble through heat and pressure.
Turn to page 249 and copy this page in your journal.

18. CHANGES TO EARTH Vocabulary
Landform different sizes and shapes of the earth’s surface. (canyons, valleys, plateaus, coasts, peninsulas, low ground {plains}, high ground {hilly or mountainous})
Weathering rocks in earth’s crust are slowly being broken into smaller pieces by nature (water, ice, temperature changes, chemicals and living things such as plant

19. 2 types of weathering Is the SLOW way earth changes
Physical weathering – only the size of the rocks are changed.
Chemical weathering – rocks are broken into smaller pieces and the material that makes up the rock or soil is also changed. (Changes rocks into different materials.)

20. How Do Weathered Materials Move?
Erosion – movement of water, ice, gravity and wind work together to move weathered pieces of rock.
Deposition – (to deposit) while some of earths surface erodes the eroded material is deposited somewhere else.

21. Erosion can bring
Landslides – soil and rock that move down hill by the force of gravity
Avalanches snow and ice that break away and move down hill by the force of gravity

22. How Do We Protect Our Land?
Terraces slow down the speed of water. Turn to page 269
Jetty
Plowing fields the opposite way the wind blows
Planting grass and trees on soil that easily blows

23. Rapid (Quick Changes) in our earth
Earthquakes
Fault: a break or crack in rocks where Earth’s crust can move (the earth’s plates)
Epicenter: the focus or center of the earthquake where it is the strongest.
Volcanos
Magma
Lava
eruption