Geology Exam 2 Study Guide

Geology Exam 2 Study Guide - Geology Exam 2 Study Guide...

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Geology Exam 2 Study Guide Plate Tectonics What are the different plate boundaries? o Divergent plate boundaries o Convergent plate boundaries o Transform plate boundaries What tectonic features are associated with each? o Divergent: mid-ocean ridges, undersea volcanoes, hydrothermal vents, hotspots, earthquakes, spreading ridges o Convergent: mountains, subduction, trenches, volcanoes, earthquakes, island arches o Transform: earthquakes Where in the world would you find each type of boundary? o Divergent: mid-ocean. o Convergent: where two plates meet (at least one must be oceanic). o Transform: easily found along divergent boundaries. Can be oceanic or continental. What types of hazards are associated with each type of boundary? o Earthquakes and volcanoes are hazard associated with these boundaries. Convergent: a boundary at which two plates move toward each other so that one plate subducts beneath the other; only oceanic lithosphere can subduct. Divergent: a boundary at which two lithosphere plates move apart from each other; they are marked by mid-ocean ridges. Transform: a boundary at which one lithosphere plates slips laterally past another Subduction zone: the region along a convergent boundary where one plate sinks beneath another Hotspot: a location at the base of a lithosphere, at the top of a mantle plume, where temperatures can cause melting and cause an isolated volcano Lithosphere: the relatively rigid, nonflowable, outer 100 to 150km thick layer of the Earth; constituting the crust and the top part of the mantle Volcanoes – Chapter 9 Why do different volcanoes behave differently? o They behave differently because there are different types of eruptions. These eruptions are affected by viscosity, gas pressure, and the environment. What are the two extreme types of magma and how do they differ in composition and viscosity? o Basaltic lava: Basaltic lava is low in silica content, hotter, and has very low viscosity. On steep slopes, it flows very quickly. Smooth glassy ridges or sharp angular fragments when it finally freezes.
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o Rhyolitic lava: rhyolitic lava is high in silica content, cooler, and has very high viscosity. Tends to accumulate in a lava dome. Has broken and blocky surfaces when it freezes What is the difference between an explosive and an effusive eruption in terms of lava viscosity, silica content, rock type, and tectonic environment? o Explosive eruptions produce clouds and avalanches of pyroclastic debris. create stratovolcanoes. Rhyolitic lava creates explosive eruptions. Rhyolitic lava contains more gas. Produced by high viscosity lavas with high silica content Felsic rocks o Effusive Eruption Produce mainly lava flows Low-viscosity balsaltic lava with a low silica content Lava sprays up in fountains because gas reaches the surface faster in runny magma and pops What effect does viscosity have on the eruptive style? o
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Geology Exam 2 Study Guide - Geology Exam 2 Study Guide...

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