PHSC 211 Chapter 2 (A grade)

PHSC 211 Chapter 2 Quiz (Fall 2020)– Liberty University (A grade) 1. What mineral composition is most characteristic of felsic rocks? a. olivine, pyroxene, and calcium-rich plagioclase b. orthoclase, quartz, and biotite c. calcium-rich plagioclase and hornblende with some olivine d. particles of volcanic ash welded together 2. What mineral composition is most characteristic of mafic rocks? a. olivine, pyroxene, and calcium-rich plagioclase b. orthoclase, quartz, and biotite c. sodium-rich plagioclase, hornblende, and quartz d. particles of volcanic ash welded together 3. What mineral composition is most characteristic of intermediate rocks? a. olivine, pyroxene, and calcium-rich plagioclase b. orthoclase, quartz, and biotite c. sodium-rich plagioclase and hornblende with some quartz or biotite d. particles of volcanic ash welded together 4. When mafic lava breaks through fissures in the continental crust, which of the following often results? a. lava plateaus b. composite volcanoes c. lava domes d. pyroclastic sheets 5. Which scenario is associated with mafic magma? a. hot, fluid lava that forms a shield volcano b. hot, fluid lava that forms a stratovolcano c. an explosive eruption that ejects pyroclastic materials d. cool, viscous magma that forms a shield volcano 6. Which scenario is associated with felsic magma? a. hot, fluid lava that forms a shield volcano b. basaltic lava that forms a stratovolcano c. an explosive eruption that ejects pyroclastic materials d. cool, viscous magma that forms a shield volcano 7. Wizard Island in Crater Lake, Oregon, is an example of a a. cinder cone. b. volcanic neck. c. lava dome. d. composite volcano. 8. A porphyritic rock forms when a. blobs of lava solidify in midair. b. there is a period of slow cooling, followed by more rapid cooling. c. magma cools slowly underground until it completely solidifies. d. a lava flow cools rapidly at the surface. 9. A porphyritic rock contains both ____________ and ____________ a. vesicles; crystals b. phenocrysts; groundmass c. pegmatites; groundmass d. phenocrysts; vesicles Question 10 through 25 are based on Lab Exercise #1: Identification of Igneous Rocks. 10. Specimen #2 has a a. pegmatitic texture. b. phaneritic texture. c. aphanitic texture. d. glassy texture. 11. Specimen #2 crystallized from a. a felsic magma. b. an intermediate magma. c. a mafic magma. d. an ultramafic magma. 12. Specimen #2 is a. gabbro. b. diorite. c. syenite. d. granite. 13. Specimen #5 is a. andesite. b. basalt. c. pumice. d. obsidian. 14. Specimen #6 is a. andesite. b. basalt. c. pumice. d. obsidian. 15. Specimen #7 has a. a pegmatitic texture. b. a phaneritic texture. c. an aphanitic texture. d. a glassy texture. 16. Specimen #7 crystallized from a. a felsic magma. b. an intermediate magma. c. a mafic magma. d. an ultramafic magma. 17. Specimen #7 is a. gabbro. b. diorite. c. gray granite. d. red granite. 18. Specimen #8 is a. an ultramafic igneous rock. b. a mafic igneous rock. c. an intermediate igneous rock. d. a felsic igneous rock. 19. Specimen #8 is a. rhyolite. b. porphyritic andesite. c. basalt. d. pumice. 20. Specimen #9 crystallized from a. a felsic magma. b. an intermediate magma. c. a mafic magma. d. a mafic lava.