1. Agenda: Wed Finish presentations Rock Cycle PPT and notes
Pres. marks handed back tomorrow

2. Rocks and the Rock Cycle!!!

3. Important Backgrounder…
All rocks are made up of 2 or more minerals, but minerals are not made up of rocks
Mineral- a naturally occurring, pure, non-living substance found in rock
There are about 3000 known minerals on earth

4. 3 Categories of Rock
Rocks are made up of a variety of minerals and can be classified into three main categories:
Igneous
Sedimentary
Metamorphic

5. Agents of Change Weathering-break down of rock into smaller particles
Erosion-wearing down of the earth’s surface followed by movement
Deposition- the laying down of sediments
Compression
Heat and Pressure- metamorphism
Melting
Cooling

6. Magma/Lava Melted or molten rock
If it is under ground, it is called Magma
If it is above ground, it is called Lava

7. Igneous Rock Ignis= fire in Latin
Formed from the cooling and hardening (solidifying) of hot melted magma that rises from deep under the earth’s crust then cools and hardens

8. Igneous Can be either intrusive or extrusive
Intrusive: form below the earth’s surface, crystals in the rock are usually larger because they cool more slowly
Extrusive: form on the earth’s surface as a result of volcanic activity, crystals are usually smaller because lava cools very quickly

9. Characteristics: glass-like or sponge-like depending on how close it is to the surface.

10. Intrusive Igneous Rock
Large crystals cooled slowly below the surface

11. Example 1: Granite

12. Extrusive Igneous Rock
Small Crystals if cooled quickly on the earths surface

13. Example 2: Basalt
Small crystal rock, usually dark in colour

14. Example 3: Pumice
Sponge like

15. Sedimentary Rocks
Sediments are small pieces of rock that have been broken down by wind/water/etc.
Formed by compression (gluing together) of sediments over millions of years

16. Sedimentary Rocks Sedimentary rocks can be classified in two ways:
Clastic: made from the “gluing” together of sediments (small pieces of rock) over time
Non-Clastic: made from remains of plants and animals

17. Sedimentary Rocks
Sedimentary rocks typically form in layers and can easily break

18. Example 1: Sandstone
Formed by sand sediments
Gritty feeling

19. Example 2: Shale
Clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments

20. Example 3: Limestone
Sedimentary rock

21. Metamorphic Rocks
Formed when pre-existing rock is transformed (changed) under tremendous heat and pressure
This occurs when layers of rock below the earth’s surface experience heat and pressure due to the overlying material

22. Characteristics: hard, dense, less porous, have crystals in non-parallel layers
This takes millions of years to occur

23. Example 1: Gneiss
Formed from granite (igneous rock)

24. Example 2: Slate
Formed from shale (sedimentary rock)

25. Example 3:Marble
Formed from limestone

26. The Rock Cycle How rocks are formed
1. Start with molten rock known as magma
2. When it cools, this melted rock hardens and turns into igneous rock
3. This rock is weathered (broken up), eroded (worn away), and deposited (collected)
4. The deposited material layer and harden, forming sedimentary rock

27. 5. If igneous or sedimentary rock undergoes pressure or heating, it becomes metamorphic rock

28. Copy this next diagram down…..this is the Rock Cycle!
Be familiar with each step of the process