1. Classifying Rocks Rocks
-naturally occurring solid mixture of one or more minerals and organic matter
-make up Earth’s crust

2. Geologists Texture -persons that collect and study rocks
-observe texture and color
-determine mineral composition
-look and feel of rock’s surface
-ex. smooth, glassy, rough, chalky

3. Grains -particles of minerals that give rock texture Size
-large grains = coarse grained
-small grains = fine grained

4. Shape of grains
Pattern
-wide range of different shaped grains
-ex. fine pieces of sand, small seeds, smooth, jagged
-grains form patterns
-ex. flat layers, swirling patterns

5. -forms from cooling of molten rock
Not visible
Igneous Rock
-no visible grain happens with fast cooling
-forms from cooling of molten rock

6. The Rock Cycle
The three main types of rock are formed during the rock cycle.

7. Igneous Rock
-any rock formed magma or lava cooling
-“igneous” means “fire”
-made of mineral crystals
-exception: different types of volcanic glass
-hard, dense, and durable
-used for tools & building materials
-classified by: origin, texture, & mineral composition

8. Origin
Extrusive Rock
-where they are formed
-two types: extrusive and intrusive
-formed from lava erupting on Earth’s surface
Fast cooling
Small crystals
-ex. Basalt and Obsidian

9. Intrusive Rock
-formed when magma hardens below the surface
Larger crystals
Slow cooling magma
-ex. Granite; forms core of many mountains

10. Sedimentary Rock
-forms from other rock, plant, & animal remains pressed together
-forms in layers

11. Sedimentary Rock Sediment
-forms from particles being weathered, eroded, and deposited by water and wind are cemented together.
-small, solid pieces of materials that come from rock or living things
*other things include: shells, bones, leaves, stems

12. Erosion
Deposition
-running water or wind loosen and carry away fragments of rock
-sediment settles out of water or wind carrying it
-after deposited; compaction and cementation change the sediment

13. Compaction
-process that presses sediments together
-happens over millions of years
-each year forms new layers compacted together
-minerals in rock dissolve in water during compaction

14. Cementation
-dissolved minerals seep into spaces
-process where dissolved minerals crystallize and glue particles of sediment together

15. Types of Sedimentary Rock
Clastic Rock
-3 major groups:
1. clastic rock
2. organic rock
3. chemical rock
-rock fragments are squeezed together
-grouped by size of rock particles of which they’re made

16. Shale
Sandstone
-forms from tiny particles of clay
-water deposits clay in very thin layers
-feels smooth & splits easily
-forms from sand on beaches, ocean floor, riverbeds
-sand is compacted and cemented
-easily absorbs water

17. Conglomerate & Breccia
-mixture of fragments of different sizes
-round edges are conglomerate
-sharp edges are breccia

18. Coal Organic Rock -made from living things
-remains of swamp plants buried in water
-layers of decaying plants are squeezed
-forms coal over millions of years

19. Limestone
-formed from coral, clams, oysters, and snails whose shells pile up
-shells are made of calcite
-calcite cements shells together to form limestone

20. Chemical Rocks
Uses of Sedimentary Rock
-minerals dissolved in solution crystallize
-also when seas evaporate and leave mineral deposits
-ex. rock salt, gypsum
-used in building materials
-decorating outside walls of buildings
-limestone used in cement

21. -formed when existing rock is changed by heat, pressure, or chemical reactions
Meta (changed) Morphos (shape)
-forms deep underground
Metamorphic Rocks

22. How Metamorphic Rocks Form
-collisions of Earth’s plates push rocks downward
-deeper a rock is buried, the greater the pressure and temperature.

23. Classifying Metamorphic Rocks
Foliated
-classify by arrangement of grains
-grains arranged in parallel layers or bands
-thin, flat layering
-may split apart along bands
-ex. slate, gneiss

24. -grains arranged randomly
-do NOT split into layers
-ex. marble & quartzite
-marble (formed from limestone) used for buildings and statues
-slate (formed from shale) used for flooring, roofing, walkways, & chalkboards
Nonfoliated
Uses of Metamorphic Rock

25. Rock Cycle
-continual process by which new rock forms from old rock material
-Earth’s constructive and destructive forces, like plate tectonics, move rocks through cycle

26. Plate Tectonics
-force that drives the rock cycle
-push rocks back into the mantle where they melt and become magma
-causes folding, faulting, & uplift that move the rocks
-two types cause movement of rocks:
1. Subducting Oceanic Plates
2. Colliding Continental Plates