Ch. 22.3 The Rock Cycle Rocks: a solid collection of minerals or mineral materials.

1. Ch. 22.3 The Rock CycleRocks: a solid collection of minerals or mineral materials.

2. Rock Types Igneous Sedimentary Metamorphic http://www.childrensmuseum.org/geomysteries/faq1.html

3. Igneous Rocks • Formed when molten rock cools and solidifies. • As rock cools, minerals in rock cool The more quickly rock cools  less crystals Obsidian has less minerals than granite. • Extrusive vs. Intrusive Extrusive - Cools on E’s surface • Examples: Obsidian & Basalt (sea floor) Intrusive – magma cools while trapped beneath E’s surface. Cooling takes millions of yrs. • Example: Granite (Lots of large crystals)

4. Obsidian Basalt Granite Devil’s Tower, WY Volcanic Plug

5. Sedimentary Rocks • Formed when pieces of rock or sediment (fragments of older rock & fossils, or living things, & minerals), get squeezed and cemented together. • Sediments bcm rocks • (1) Layers of sediment get compressed from weight above, forming rock (LITHIFICATION) • (2) Minerals dissolved in water seep b/w bits of sediment and CEMENT them together • Named according to size of fragments they contains • Conglomerate – pebbles & big fragments • Sandstone – sand • Mudstone – fine mud (CAN’T SEE INDIVIDUAL GRAINS) • Limestone – fossils of organisms that live in the water.

6. Types of Sedimentary Rocks A. Clastic: form fr. broken fragments of other rocks (usu. Held together by cement) Ex.: Conglomorate, sandstone, mudstone B. Chemical: form fr. minerals that precipitate out of solution. Ex.: Tufas (calcium cabonate rocks) C. Organic: form as a result of organic (living) processes Ex. :Limestone made from shells of organisms or rocks w/ fossils in them

7. Conglomerate: Clastic Tufas (salt towers): Chemical Limestone Cliffs of Dover: Organic Sandstone: Clastic

8. Metamorphic Rock • Formed when HEAT, PRESSURE, or CHEMICAL PROCEESES w/in E cause changes in the texture and mineral content of rocks (metamorphic = to change forms in Greek) • Rock undergoes a change w/out melting over millions of yrs. • Fossils get destroyed Examples: • Limestone + heat + pressure  Marble • Mudstone/Shale + heat + pressure  Slate

9. Foliation: Minerals & crystals in rocks realign into bands in metamorphic rocks.

10. http://www.uwgb.edu/dutchs/GRAPHIC0/ROCKMIN/RockCycle7.gif

11. Rock Cycle Process of events in which rocks can be weathered, melted, altered, and formed over millions of yrs. http://www.ltcconline.net/julian/california/cycle.gif

12. Rock Cycle Processes SEDIMENTARY ROCKS: on surface Weathering / Deposition of Sediments / Cementation (lithification) Sedimentary Rock IGNEOUS ROCKS: On surface (extrusive) or interior (intrusive)Melting / Cooling & Solidifying  Igneous Rock Metamorphic Rock: Usually inside Earth (@ depths associated w. higher pressures & temps.) Heat / Pressure  Metamorphic Rock Weathering: wind & water breaks rocks down into fragments (Makes sedimentary) Cementation: Water “glues” sediment together to make rock

13. Rock ID Check Up Answer these questions on lined paper in complete sentences. • Which rocks were igneous? List # and name. • Which of igneous rocks would be considered EXTRUSIVE? • Which rock was an intrusive igneous? What characteristic can you observe to confirm that it is intrusive? • Did granite form quickly or slowly? How do you know? • Which rocks were sedimentary? List # and name. • Which sedimentary rocks were clastic? • Which sedimentary rock was organic or chemical? • Which rocks were metamorphic? List # & name. • Shale can turn into slate. What conditions would change shale into slate? • Which rock (or rocks) could you find fossils in? Support your answer.