READING QUESTIONS: Chapter 2 (Rocks) PSCI 131 18/WI 70 pts NAME DUE: Monday, January 29 Igneous Rocks: Formed by Fire (p. 34-43) 1. What is magma? 2. Extrusive igneous rocks form at the Earth s, and intrusive igneous rocks form deep. (2 pts) 3. Fill in the blanks (p. 34): The rate of cooling strongly influences. If magma cools very, ions can migrate over great distances. Consequently, cooling results in the formation of fewer, crystals. On the other hand, if cooling occurs, the ions lose their motion and quickly combine. This results in a large number of crystals all competing for the available ions. Therefore, rapid cooling results in the formation of a solid mass of intergrown crystals. (7 pts) 4. To what mineral group do almost all minerals found in igneous rocks belong? 5. Fill in the blanks (p. 38): If molten rock containing some crystals moves to a different - for example, by erupting at the surface the remaining portion of the lava cools more. The resulting rock, which has crystals embedded in a matrix of crystals, is said to have a texture. (7 pts)
6. Match each of the following igneous textural terms to the correct definition: (3 pts) a. Coarse-grained Composed of unordered atoms b. Fine-grained Crystals large enough to be seen without a microscope c. Vesicular Contains voids left by escaping magma gases d. Glassy Composed of two distinctly different crystal sizes e. Porphyritic Fragmental; composed of ash and larger rock fragments f. Pyroclastic Crystals too small to see without a microscope 7. Fill in this igneous classification chart with the correct rock names. Refer to Figure 7 on page 39. (5 pts) Coarse-grained Granitic Andesitic Basaltic Fine-grained Glassy Vesicular (give two rock names) Pyroclastic 8. Fill in the blanks (p. 42-43): Crystal settling occurs when the earlier formed minerals [in a magma] are more (heavier) than the liquid portion and towards the bottom of the magma chamber When the remaining molten material solidifies it will form a rock with a much from the parent magma. (4 pts)
Sedimentary Rocks: Compacted and Cemented Sediment (p. 43-49) 9. What two minerals are most abundant in detrital sedimentary rocks? (2 pts) 10. Match each detrital sedimentary rock to its description. (4 pts) a. Conglomerate Coarse-grained, angular sediment b. Breccia Very fine-grained sediment c. Sandstone Medium-grained sediment, little or no feldspar grains d. Shale Coarse-grained, rounded sediment 11. For each sedimentary rock listed, indicate whether it is biochemical or chemical. (3 pts) a. Coquina b. Chalk c. Rock salt d. Crystalline limestone e. Travertine f. Fossiliferous limestone 12. Fill in the blanks (p. 47-48): refers to the processes by which sediments are transformed into solid sedimentary rocks. One of the most common processes is. As sediments accumulate through time, the weight of the overlying sediments the deeper sediments. As the grains are pressed closer and closer, is greatly reduced Compaction is most effective in converting very into sedimentary rocks. (5 pts) 13. Fill in the blanks (p. 48): Because sand and coarse sediments are not easily compressed, they are generally transformed into sedimentary rock by the process of. The cementing materials are carried in a that percolates through the pore
spaces between particles. Over time, the cement onto the sediment grains, fills in the open spaces, and acts like a to join the particles together. (4 pts) 14. Give an example of one rock type that is lithified by compaction, and one that is lithified by cementation. (2 pts) a. Compaction: b. Cementation: Metamorphic Rocks: New Rock from Old (p. 50-54) 15. Fill in the blanks (p. 50): Metamorphism is a process that leads to changes in the, (for example, grain size), and sometimes of rocks Most metamorphic changes occur at the elevated and that exist in the zone beginning below Earth s surface and extending into the. (7 pts) 16. During metamorphism, rocks usually get hot enough to melt completely. TRUE or FALSE 17. How does contact metamorphism take place? (2 pts) 18. List the four agents of metamorphism. (2 pts) a. b. c. d. 19. Which agent is the most important, and why? (3 pts)
20. What is the difference between differential stress and confining pressure? (2 pts) 21. Fill in the blanks (p. 53): Foliation refers to any nearly arrangement of mineral grains or structural features within a rock In metamorphic environments, foliation is ultimately driven by that rock units, causing mineral grains in preexisting rocks to develop alignments. (4 pts) 22. EXTRA CREDIT: Label each photo below with the type of foliation shown (rock cleavage, compositional banding, or alignment of flat minerals each will be used once). (3 pts)