Geology 105 - Dynamic Earth Test Questions with Correct Answers Fully Solved

Geology 105 - Dynamic Earth Test Questions with Correct Answers Fully Solved viscosity - Answers internal resistance to flow; may be low, medium, or high, and it controls whether magma flows away or piles up volatiles - Answers chemical species that under normal conditions of pressure and temperature exist in the gaseous phase; may be low, medium or high and may ooze out harmlessly or blast out explosively volume - Answers may be small, medium or large; correlates fairly well with eruption intensity; the greater the volume, the more intense the eruption decompression melting - Answers Melting caused by a decrease in pressure; most of the rock that melts to form magma does so b/c the pressure on it decreases, not b/c more heat is added icelandic volcanoes - Answers nonexplosive eruptions; low water content, low viscosity; basalt Hawaiian volcanoes - Answers nonexplosive eruptions; low water content and viscosity; basalt Examples: Kilauea, 1971 "Fire-Fountaining" (Molten magma is ejected from cracks to produce fire fountains that jet the lava 30 -50 feet into the air), Kilauea Iki, 1959, Puu Oo, 1984 Strombolian volcanoes - Answers somewhat explosive; moderate water content, low to moderate viscosity; basalt to andesite Ex: The island of Stromboli, Mount Etna, Sicily. vulcanian volcanoes - Answers explosive eruption, steam-blasts; moderate to high water content, moderate to high viscosity; basalt to rhyolite Ex: Mount St. Helens plinian volcanoes - Answers the largest, most violent, and most destructive of all eruptions; high water content and viscosity; andesite to rhyolite Ex: Lassen Volcano, California, 1915, Mount Redoubt, Alaska, 1990, Pinatubo Volcano Philippines, 1991 pyroclastic - Answers gas blasting into the atmosphere takes along chunks of magma and older rocks pahoehoe - Answers a smooth, ropy surface; tends to be more fluid (low viscosity) aa - Answers rough, blocky surface; slow moving, higher viscosity; thick flows pillow lava - Answers ellipsoidal masses formed in water; thicker flows than aa obsidian - Answers cooled volcanic glass; nonporous glass pumice - Answers porous glass (froth) scoria - Answers rough crusts or chunks of basaltic rock full of holes made by expanding gases before solidification shield volcanoes - Answers made of fluid basalt lavas flows, that flow much further, thus giving them their shield-like shape; low viscosity, low volatiles, large volume flood basalts - Answers largest volcanic events known on Earth; 2 important characteristics are (1) the immense amounts of mass and energy they pour onto Earth's surface,