1. Earth Science A study in Change: Rocks Watch for & It will tell you when/where information will be used in this unit!

2. Rocks  Any sold mass of minerals, or mineral like material.  Inorganic solid, crystalline structure, definite chemical composition.  Isn’t a rock, just a rock? So what?  They aren’t static objects. They change with the earth and can tell us about it. Their timeline is just different than ours!

3. Most Common Minerals (pg 35) Know these!

4. Main Types of Rock  Igneous  Sedimentary  Metamorphic  Processes that change rock  Melting & cooling  Weathering & erosion  Compaction & cementation  Heat & Pressure

5. Igneous Rocks  Form from the cooling of magma or lava.  Magma = molten rock below the surface of the earth (625 o C or 1032 o F, low end)  Intrusive igneous rock  Composed of silicon, oxygen, & gases like water vapor  Lava = molten rock above the surface of the earth  Extrusive igneous rock  Similar in composition to intrusive igneous, without the gases (low pressure = escape)

6. Igneous Characteristics  Texture  Course grained - large crystals caused by slow cooling of magma, usually intrusive  Fine grained - small interlocking crystals due to relatively fast cooling  Glassy - cools too quickly to form crystals, may appear glassy, may not (obsidian vs. pumice)pumice  Porphyritic - both large and small crystals due to varying rates of cooling

7. Igneous Characteristics  Composition  Granitic - made up of mostly quartz or feldspar  Tend to be light colored  Basaltic- made up of mostly dark silicates, rich in magnesium and iron  Tend to be dark colored  Other - either a combination of the above or ultramafic (really old rocks)

8. Igneous Rock Examples Obsidian Lava flow= basaltGranite AphaniticPorphyritic

9. Sedimentary Rocks  Form when existing rocks are broken down into sediments and the sediments are cemented together to form a “new” (recycled) rock.  Weathering - process by which existing rock is broken down.  Physical weathering - breaking of a large rock into smaller pieces(physical changes)  Chemical weathering - changing of rock composition due to chemical changes

10. Processes Forming Sedimentary Rocks  Weathering  Ice wedging, root action, acid rain  Faster when there is lots of water in environment  Erosion - process by which weathered sediment is transported away from original parent rock.  Wind, Water, Ice, Gravity  Deposition - fancy term for when the eroded particles are dropped!

11. Processes Forming Sedimentary Rocks  Compaction - process of squeezing or smashing of deposited sediments into a smaller volume  Usually due to the weight of new sediments being deposited above.  Cementation - process of gluing sediments together  Dissolved minerals precipitate out of solution and are deposited in the space between sediments.

12. Classification of Sedimentary Rocks  Clastic Sedimentary- composed of weathered sediments and minerals  Conglomerate, sandstone, shale  Bits and pieces stuck together.  Looks or feels chunky  Chemical Sedimentary - composed from precipitates of dissolved minerals  Limestone, rock salt, gypsum(drywall)

13. Sedimentary Rock Examples Sandstone- Clastic Limestone -Chemical Conglomerate - Clastic

14. Metamorphic Rock  Formed when existing rocks are changed by heat and pressure(causes chemical reactions).  Heat - provides energy for chemical reactions  Earth structure provides heat source  Amount required to change a rock depends upon its mineral composition  Chemical Reactions - hot water containing other substances that allow recrystallization  Pressure - from all directions, affected by depth

15. Types of metamorphic rock  Foliated - layered or banded appearance of metamorphic rocks  Due to parallel orientation of mineral crystals  Forms when sedimentary rock is smashed  Nonfoliated - does not have banded texture, usually made up of only one mineral.

16. Metamorphic Rock examples Sandstone, before/after, nonfoliated Slate (parent = shale) foliated

17. Metamorphic Examples Marble nonfoliated Quartzite nonfoliated

18. Rock Cycle (final exam)