Agenda: Wed

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

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