Chapter 5 and 6 Study Guide Keys Study Guide – Chapter 5 – Igneous Rocks Section 5.1 What are igneous rocks? 1. magma 2. igneous rock 3. lava 4. basaltic 5. rhyolitic 6. true 7. false 8. true 9. true 10. false 11. true 12. As the pressure on a rock increases, its melting point increases. 13. No; different minerals have different melting points. 14. Temperature increases with depth in Earth’s crust. 15. Pressure increases with depth from the weight of overlying rock. 16. melting points 17. partial melting 18. elements 19. reverse 20. fractional crystallization 21. magma 22. discontinuous reaction series 23. continuous reaction series 24. calcium 25. sodium 26. When magma cools rapidly, the calcium-rich cores are unable to react completely with the magma, resulting in a zoned crystal with sodiumrich outer layers and calcium-rich cores. 27. At the end of magma crystallization, the remaining melt, which is enriched with silica and oxygen, finally crystallizes, forming quartz.
Section 5.2 Classification of Igneous Rock 1. ultrabasic 2. intermediate 3. granitic 4. basaltic 5. ultrabasic 6. basaltic 7. intermediate 8. basaltic 9. granitic 10. ultrabasic 11. Obsidian has a very small grain size. 12. Obsidian is extrusive; its glassy texture without obvious grains probably formed as lava cooled quickly on Earth’s surface. 13. Gabbro has large crystals, in contrast to obsidian’s crystals, which are very small. 14. Gabbro is intrusive; its large grains probably formed as magma cooled slowly below Earth’s surface. 15. c. 16. d 17. b 18. e 19. f 20. a 21. to observe the shapes of mineral grains 22. Intrusive igneous rock cools slowly beneath Earth’s surface, while extrusive igneous rock cools rapidly at or near Earth’s surface. 23. They have space in which to grow freely. 24. Porphyritic rocks are characterized by large, well-formed crystals surrounded by finer-grained crystals. 25. Porphyritic textures can form if a slowly cooling magma suddenly begins cooling rapidly. 26. d 27. a 28. c 29. b 30. a 31. c 32. a 33. d 34. b
Chapter 5 and 6 Study Guide Keys Chapter 6 Study Guide – Sedimentary & Metamorphic Rocks Section 6.1 Formation of Sedimentary Rocks 1. Sediment 2. unsorted deposits 3. chemical weathering 4. cementation 5. clastic sediments 6. sedimentary rock 7. deposition 8. lithification 9. physical weathering 10. sorted deposits 11. false 12. true 13. false 14. true 15. false 16. false 17. true 18. true 19. bedding 20. transport 21. graded bedding 22. cross-bedding 23. sand dunes 24. ripple marks 25. fossils 26. lithification Section 6.2 Types of Sedimentary Rocks 1. clastic 2. clastic 3. biochemical 4. biochemical 5. clastic 6. chemical 7. chemical 8. clastic 9. chemical 10. biochemical 11. Shells from dead sea animals settle to the bottom of the ocean and form sediments. During burial and lithification of these sediments, calcium carbonate precipitates out of water and crystallizes between grains of carbonate sediment, forming limestone. 12. Fossils provide information about living things that existed in the past.
13. Some sedimentary features indicate the location and direction of flow of ancient rivers, the wave direction over lakes, and ancient shoreline positions. Section 6.3 Metamorphic Rocks 1. a 2. d 3. g 4. f 5. e 6. b 7. c 8. low, intermediate, and high grades 9. intermediate and high grades 10. low grade 11. a 12. b 13. b 14. d 15. c 16. c 17. d 18. a 19. a 20. igneous rocks 21. sedimentary rocks 22. metamorphic rocks 23. Igneous rocks cool and crystallize from magma. 24. The igneous rocks become sediments. 25. Sediments undergo deposition, burial, and lithification to become sedimentary rock. 26. heat and pressure 27. Possible response: The metamorphic rock can melt to form magma that cools and crystallizes to form igneous rock. 28. The sandstone can be uplifted, weathered, and eroded to form sediments.
