1. ALL ABOUT ROCKS Learning Objectives:
Learn everything you need to know about sedimentary rocks.
Learn everything you need to know about igneous rocks.
Learn everything you need to know about metamorphic rocks.
The Rock Cycle

2. Sedimentary Rock Formation
Sedimentary rocks are made from sediment, small pieces of rock (any type).
How is sediment formed?
Weathering

3. Sedimentary Rock Formation (Steps)
Weathering
Erosion
Transportation
Deposition
Compaction
Cementation

4. Weathering Weathering = wearing away Types of weathering Chemical
Physical

5. Chemical weathering = weathering caused by substances in air or water having a chemical reaction with the rock

6. What type of chemical do you think weathers rocks?
ACID
Rainwater is slightly acidic because carbon dioxide reacts with water to for carbonic acid.
However, acid rain from pollution is a stronger acid and weathers rocks more quickly.

7. Practical: Chemical weathering
Put a few drops of dilute acid onto the different types of rocks and write down your observations.

8. Physical weathering = weathering caused by physical changes such as:
changes in temperature
freezing and thawing
the effects of wind, rain, and water.

9. Physical Weathering Examples
Freeze-Thaw Weathering
Onion Skin Weathering

10. Physical Weathering Examples
Glacial Weathering

11. Weathering happens to all rocks
Suggest which type you think will weather the fastest and explain why.
Sedimentary
Weakest bonds between the grains
Porous, water/acid will get into the rock and weather from the inside or freeze and break the rock.

12. Erosion = pieces of rock fall off

13. Transportation = sediment is moved to lakes or seas
Movement of wind, water, or ice (glaciers) moves the sediments towards the ocean.

14. Deposition = sediment falls to the bottom of the sea and builds up in layers

15. Compaction = the layers on the bottom are compressed from the weight of the layers on top
The pressure from the weight of the sediments on top squeeze the water out from between the grains.

16. Cementation = dissolved minerals “glue” the sediments together
When the water is squeezed out, dissolved minerals are left behind and act as a glue cementing the sediments together.

18. Formation of Igneous Rocks
Magma = molten (hot liquid) rock deep underground
Lava = magma that is above ground
Igneous rocks are formed when magma or lava cools and solidifies.

19. Crystal Size Depends on the Speed of Cooling
Extrusive igneous rocks – magma “exits”, lava cools quickly in the air and forms rocks with small crystals (not enough time for crystals to grow)
Intrusive igneous rocks – magma is “in” the ground, magma cools slowly underground and forms rocks with large crystals

20. Crystal Size Depends on the Speed of Cooling
Fast Cooling
Above Ground
Slow Cooling
Below Ground

21. Metamorphic Rock Formation
Metamorphic rocks are formed when rocks are under high heat and high pressure from being deep underground.

22. The high pressure is what causes the crystals to be flattened.
The high heat and high pressure makes the rocks have a chemical change.
The high pressure is what causes the crystals to be flattened.

23. Weathering, Erosion, etc.
Rock Cycle
Weathering, Erosion, etc.
High Heat and Pressure
Melting and Cooling