The document provides information about igneous rocks including: 1) Igneous rocks form from the solidification of magma and their texture and crystal size depends on the cooling rate, with slow cooling forming large crystals and fast cooling forming small crystals. 2) Igneous rocks can be intrusive, forming below the surface, or extrusive, forming on the surface such as lava. 3) Composition of igneous rocks can be felsic, mafic, or intermediate depending on the amounts of silica and iron/magnesium minerals present.

1. Mrs. Harris’s slides: Igneous Metamorphic Sedimentary

2. Earth Science Igneous Rocks

3. Today Igenous rocks Intrusive Extrusive Crystal size Texture Composition

4. Igneous Rock A rock made from the solidification of cooled magma Rocks melt = magma Magma cools = igneous rock What makes rock melt?

5. Making Magma Temperature 1,000-2,000 F o Different minerals melt at different temperatures (like cheeses) Pressure Higher pressure requires higher temperatures to melt Water and/or Carbon Dioxide These lower the pressure which lowers the temperature required to melt

6. Partial Melting Certain minerals will melt before others based on their chemical composition Like having butter, chocolate, and cheese in a pot… what melts first?

7. Types of Igneous Intrusive Form below the surface Extrusive Form on the surface

8. Cool It! Rate of cooling determines size of the crystals Slow = large Intrusive Fast = small Extrusive

9. Ever made rock candy?

10. Slow Cooler Large crystals Course texture Intrusive or extrusive?

11. Quick Cooler Small crystals Fine texture Intrusive or extrusive?

12. Can it be both?

13. Absolutely! When magma cools quickly at first and then slower it makes both crystal sizes. This is called porphyritic

14. Other textures Glassy Vesicular

15. Intrusive Magma pushed into existing rock and cools

16. Intrusive

18. Extrusive Lava Magma on Earth’s surface Pyroclasts Ashes to rocks, erupted Pyroclastic flow Hot, dry ash, rock, and gasses

21. Composition Felsic Lots of silica Light in color Mafic Iron & magnesium Darker in color (sometimes has ferromagnesium minerals) Intermediate rocks are in between felsic and mafic.

22. Vocab Textures: Fine Course Porphyritic Glassy Vesicular Composition Felsic Mafic Intermediate

23. What do you call… A rock has cooled quickly and is dark in color…

24. What do you call… A rock has cooled quickly and is dark in color…

25. What do you call… A rock has cooled slowly and is light in color…

26. What do you call… A rock has cooled slowly and is light in color…

27. What do you call… A rock has cooled fast then slow and is light and dark in color…

28. What do you call… A rock has cooled fast then slow and is light and dark in color…

30. This week… 6-2 quiz Unit 6 discussion Unit 6 assignment 7-2 quiz 7-2 quiz Next class… Metamorphic Sedimentary

31. 10/20/10

32. Metamorphic Rock What is it? When does it happen? Where do they occur? Types of metamorphism 10/20/10

33. Metamorphic Rock Meta & morph = change shape Rocks changed by heat, pressure, and fluids 10/20/10

34. Making Metamorphic Rock Two rules for changes:  Below the surface  Solid state 10/20/10

35. Metamorphic Heat At least 250 C o Geothermal gradient Earth gets hotter by 25 C o for every km down Magma = Contact metamorphism Changes bonding structure 10/20/10

36. Metamorphic Pressure Pressure: need 2 kilobars Depth Add a kbar for every 3-ish km down Convergent and transform boundaries = regional metamorphism Strains bonds, some break, more compact structure 10/20/10

37. 10/20/10

38. 10/20/10

39. Metamorphic Chemical Fluid Fluid carrying dissolved ions Magma chamber Ridge vents Changes minerology 10/20/10

40. After metamorphism… Recrystallization Crystal size changes Compaction Pore space reduced Foliation (not always) Parallel platy grains 10/20/10

41. 10/20/10 Slate

42. 10/20/10 Schist

43. 10/20/10 Gneiss

44. Sedimentary Rock Rocks formed by one of 3 processes: Physical processes Plants and animals Chemical processes

45. Sedimentary: Physical Process Formed by the physical breakdown of pre-existing rocks Eroding agents like water, wind, ice Transported (load), deposited, lithification (next slide) “ Clastic rocks”

46. Lithification- sediment changes to rock Compaction- increased pressure & temp, removes water Cementation- any spaces become filled by minerals out of solution Mineralogic change- some break down, others change Sedimentary: Physical Process

48. Sandstone

49. Sedimentary: Plants & Animals Made of plants and/or animals Examples: Shells, bacteria, compressed plants Organic sedimentary rock

50. Oil Shale- Tropical plants, compressed

51. Stromatolites- made by algae

52. Sedimentary: Chemical Process Rocks made of crystals from solution Chemicals in water, water evaporates, crystals grow Called “evaporite” Chemical Sedimentary Rocks

53. Halite- a.k.a. salt

54. Fossils

56. Looking Ahead: Unit 7 Assignments Part 1 is a unit test Part 2 is a short report Next week: ores & mining