1. Chapter 10 ROCKS

2. Ch. 10.1 Rocks and the Rock Cycle Magma is the parent material for all rocks. There are three types of rocks, classified by how they are formed.

3. Igneous Rocks Formed when magma or lava cools and hardens. Igneous is from the Latin term from fire.

4. Sedimentary Rock Formed when small fragments of rock or organic material harden after being compressed and cemented together.

5. Metamorphic Rock Forms when heat and or pressure, or chemical processes change the form of existing rock.

6. The Rock Cycle Any type of rock can be changed into any other kind of rock and back again. Processes are… Melting and cooling—igneous. Compaction and cementation— sedimentary. Heat and pressure—metamorphic.

7. Characteristics of Igneous Rocks Large or small crystals depending on cooling rate. The slower the cooling rate, the larger the crystals. Color depends on lava or magma type…felsic produces lighter rocks; mafic produces darker rocks. May have trapped gas bubbles (pumice and scoria).

8. Generally composed of silicate minerals.

9. Characteristics of Sedimentary Rocks Form from cemented together rock fragments, organic material, or from minerals that precipitate out of water. May have layered structure from deposition of various kinds of sediment deposited in silt beds. Moving wind or water may cause ripple marks. May contain fossils…remains or traces of ancient plants or animals.

10. Characteristics of Metamorphic Rock Local volcanism may cause contact metamorphism. Tectonic activity may cause widespread regional metamorphism. Usually deep within the earth. May have enlarged or alternating bands of crystals (foliated). May change soft sedimentary rock into hard, durable rock.