1. Rocks and the Rock Cycle Chapter 7

2. Groups of Rocks 1. Igneous: meaning from “fire” -forms when magma cools and hardens. 2. Sedimentary: forms when sediments harden after being compressed.

3. 3. Metamorphic: rock formed from processes and forces such as pressure, heat, and chemicals. -metamorphic means “changed form.” All three groups of rocks can change from one group to another. This is called the rock cycle.

4. Igneous Rock Two types of igneous rocks: Two types of igneous rocks: 1. Intrusive- magma cools slowly in the earth. Produces large crystals. Examples: granite present, quartz, feldspar and mica.

5. 2. Extrusive- rapid cooling of lava on the earth’s surface. Examples: Basalt (black, no crystals), low in silica, Obsidian (volcanic glass), Pumice (bubbles).

6. Igneous Rock Structures Intrusions: underground rock masses made up of intrusive igneous rock. (batholiths, stocks, laccolith, sill, dike) Intrusions: underground rock masses made up of intrusive igneous rock. (batholiths, stocks, laccolith, sill, dike) Extrusions: surface rock masses made up of extrusive igneous rock. (volcanic neck, lava plateau) Extrusions: surface rock masses made up of extrusive igneous rock. (volcanic neck, lava plateau)

8. Sedimentary Rock Three types: clastic, chemical sedimentary (evaporate), and organic sedimentary. Three types: clastic, chemical sedimentary (evaporate), and organic sedimentary. 1. Clastic: cemented together. Classified by the size of the sediments. Examples: Sandstone- fine grained particles.

9. Conglomerate-rounded or gravel sized fragments. Breccia- angular sharp cornered fragments. Shale- clay-sized particles, flat layers.

10. 2. Chemical Sedimentary: comes from rocks that were once dissolved in water. Evaporites: gypsum, limestone, and halite.

11. 3. Organic Sedimentary: formed from the remains of once living organisms. Examples: coal (dead plants and animals)

12. Features of Sedimentary Rock: -stratification -ripple marks -mud cracks -fossils -concretions (geodes)

13. Metamorphic Rock Formed from the forces of heat and pressure. Formed from the forces of heat and pressure. Forms deep beneath the surface of the earth. Forms deep beneath the surface of the earth. Formed from existing igneous, sedimentary, or metamorphic rock. Formed from existing igneous, sedimentary, or metamorphic rock.

14. Parent Rock Metamorphic Rock SandstoneQuartzite SandstoneQuartzite LimestoneMarble LimestoneMarble GraniteGneiss GraniteGneiss CoalDiamond CoalDiamond ShaleSlate ShaleSlate SlateSchist SlateSchist