EAR 110 1st EditionExam # 2 Study Guide Lectures: 8 - 14Lecture 8 Earth MaterialsWhat is the structure of a silica tetrahedron and how do they bond? Answer: One silicon atom bonded to 4 oxygen atoms forming a pyramid. They bond in a variety of ways – single chains, double chains, silica sheets or frame networks. Lecture 9Igneous Rocks How does the rate of cooling affect the size of crystals in igneous rocks?Answer: Crystals take time to grow; so larger crystals indicate a slower cooling rate. Small or no crystals indicate a faster cooling rate. What are the differences between felsic and mafic magma? Answer: Felsic magmas are high in silica and thick (viscous). Mafic magmas are low in silica content and thin. Lecture 10What are some processes that cause rocks to melt?Answer: Decrease in pressure (decompression melting), increase in temperature, or addition of water content. Lecture 11VolcanoesWhat are the four types of volcanoes?Answer: Scoria cones, shield volcanoes, composite volcanoes, volcanic domes. Why do shield volcanoes have gentle slopes and composite volcanoes have steep slopes?Shield volcanoes generally form from lava flows that are thin and flow easily (mafic). Compositevolcanoes form from intermediate or felsic lava flow that are thicker and build up a steep slope. Lecture 12 List some ways that volcanoes are monitored for activity?Answer: Volcanoes are monitored for seismic activity, changes in gas composition, and visual inspection of lava flows or activity.Sedimentary RocksHow does the depositional environment affect the characteristics of sedimentary rocks?Answer: If a depositional environment is further away from the source, the sediment will be rounder and well sorted. If the depositional environment is close to the source, the sediment will be angular and not well sorted, but mixed. Lecture 13 How is the color of sedimentary rocks an indicator of the environment in which they formed?Answer: If sandstone is red, it formed in an oxygen rich environment where oxidation occurred. If sandstone is white or tan, it formed in a low oxygen environment, such as underwater. What are some resources found in sedimentary rocks?Answer: Some resource are petroleum, coal, uranium, and salt. Lecture 14 Metamorphic RocksWhat are some ways that rocks respond to stress?Answer: Rocks can get displaced, rotated, or strained. They can fold or fracture along fault lines.What are the three main types of faults?Answer: The three main types of faults are normal, reverse, and