Rocks are naturally occurring mixtures of minerals, mineraloids, glass or organic matter that are divided into three main types - igneous, sedimentary, and metamorphic - based on how they were formed. Rocks are continually changed over time by various geological processes through the rock cycle, where one type of rock can be transformed into another through weathering, erosion, melting and other changes. The core, mantle and crust act as a recycling machine that redistributes rocks.

1. ROCKS

2. What is a Rock? Naturally-occurring mixtures of minerals , mineraloids, glass or organic matter.

3. What is a Rock? Rocks are divided into 3 groups based on how they were formed: IGNEOUS SEDIMENTARY METAMORPHIC

4. What is the difference between a rock and a mineral? Rocks are made up of ONE or MORE minerals.

5. Once a rock is formed, does it stay the same rock forever? NO !

6. Rocks are continually changed by many processes, such as weathering, erosion, compaction, cementation, melting, and cooling Rocks can change to and from the three types

7. What is the process through which rocks change? The Rock Cycle—earth materials change back and forth among the different types of rocks

10. No set path a rock takes to become another kind of rock

11. Weathering, Erosion, Compaction, Cementation Recrystallization Weathering, Erosion, Compaction, Cementation Recrystallization Melting, Solidification Melting, Solidification IGNEOUS SEDIMENTARY METAMORPHIC

12. How are rocks redistributed? The core, mantle, & crust are one giant rock recycling machine

13. ***Watch the Rock Cycle by Brainpop What do igneous rocks form from? What kind of rock is sandstone? What are metamorphic rocks formed by?

14. “ Ignis” = Latin for “ fire ” Formed from the cooling of either magma or lava The most abundant type of rock Classified according to their origin and composition Igneous Rocks

15. ORIGIN— Where rocks are formed Below ground = from magma (intrusive igneous rock) Usually have LARGE crystal grains (they cooled slowly )

16. Some have large & small crystals (called porphyritic)

17. Above ground = from lava (extrusive igneous rock) Usually have SMALL or NO crystals (they cooled too quickly )

18. Peridotite: Intrusive or Extrusive? Why?

19. Granite: Intrusive or Extrusive? Why?

20. Porphyry: Intrusive or Extrusive? Why?

21. Obsidian: Intrusive or Extrusive? Why?

22. COMPOSITION— What kind of substances the rocks are made of

23. Basaltic Igneous Rocks —made from lava/magma that is low in silica , rich in iron and magnesium. Rocks are dark- colored .

24. Granitic Igneous Rocks—made from magma/lava high in silica and oxygen. Rocks are light -colored.

25. Andesitic Igneous Rocks—have a composition between basaltic and granitic .

26. Diorite

27. Basalt

28. Granite

29. Formed from sediments (rock fragments, mineral grains, animal & plant remains) that are pressed or cemented together or when sediments precipitate out of a solution. Sedimentary Rocks

30. These sediments are moved by wind, water, ice or gravity. Sedimentary rocks represent 7% of the Earth’s crust, but they cover 70% of the Earth’s surface. Sedimentary rocks are fossil -carrying rocks. Sedimentary Rocks

31. What turns sediments into solid rock? Water or wind breaks down and deposits sediment (erosion & deposition)

32. The heavy sediments press down on the layers beneath (compaction)

33. Dissolved minerals flow between the particles and cement them together (cementation)

34. How can sedimentary layers help us understand the age of fossils? As sedimentary rocks are deposited, they form horizontal layers Scientists know that the layers on top (and the fossils in the top layer) are YOUNGER than the fossils in lower layers.

35. 3 Types of Sedimentary Rocks: Clastic (also called Detrial)—made of broken pieces of other rocks

36. Organic—remains of plants and animals are deposited in thick layers Examples Fossil rich limestone is made from the shells of ocean animals; used to make chalk 3 Types of Sedimentary Rocks:

37. Chemical— minerals dissolved in lakes, seas, or underground water 3 Types of Sedimentary Rocks: Mineral crystals are made as the shallow water that has flooded the bottom of Death Valley evaporates. Click on image for full size ( 66K JPG ) Courtesy of Martin Miller, University of Oregon

38. Examples Limestone made when calcite mineral precipitates from sea water Rock Salt —made from evaporation of sea waters

39. Rocks that have changed due to intense temperature and pressure “ Meta” means “ change ” and morphosis means “ form ” in Greek Igneous, sedimentary and other metamorphic rocks can change to become metamorphic rocks Metamorphic Rocks

40. What occurs in the Earth to change these rocks? Pressure from overlying rock layers High heat , but not enough to melt the rock Rocks may be flattened or bent or atoms may be exchanged to form new minerals.

41. *You can think of metamorphic rocks as a squished peanut butter & jelly sandwich in your lunch.

42. How are metamorphic rocks classified? Foliated—mineral grains are flattened and line up in parallel bands Example : gneiss formed from rearrangement of minerals in granite into bands

43. How are metamorphic rocks classified? Non-Foliated— No bands are formed Example : marble formed from limestone

44. Where do metamorphic rocks usually form? Where magma intrudes relatively cool rock Near colliding plates (near mountain ranges) Places that are covered miles thick with other rock causing pressure When hot water intrudes rock Where a meteorite strikes Earth (rare) Where lightning bolts strike rocks (rare)