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60) Lava flows are typically finer grained than intrusive Igneous rocks. Why? A) Intrusive magma is cooler because it is well Insulated by the surrounding rock. B) Intrusive magma flows onto the Earth’s surface and cools very slowly, allowing many small mineral grains to grow C) The extrusive magma cools quickly so the mineral grains do not have time to grow. D) The extrusive magma, because it is deep below the surface, cools very slowly producing very small mineral grains. 61) Visible quartz and potassium feldspar grains are the main constituents in a A) granite B) gabbro C) basalt D) rhyolite 62) Which natural phenomenon occurs for many years after major explosive volcanic eruptions such as Tambora and Pinatubo? A) heavy falls of volcanic ash within 100 km of the volcano B) unusually warm weather in the tropics and subtropics C) a worldwide rise in sea level of one to three centimeters D) brilliantly colored sunrises and sunsets has the same mineral composition as andesite. A) Basalt B) Granite C) Gabbro D) Diorite 64) NO QUESTION-LEAVE BLANK ON SCANTRON 65) is named for a prominent, volcanic mountain range in western South America, A) Basalt resource was ourse Hero.com B) Andesite C) Pegmatite D) Peridotite via 66) tend to increase the explosive potential of a magma body beneath a volcano. A) High viscosity and dissolved gas B) High viscosity, low dissolved gas content Chlow silica content, low viscosity D) Low viscosity, low dissolved gas content 67) The ocean basin is rimmed by the most subduction zones. A) Atlantic CS 3) Indianned with Pacific Scanner D) Arctic
60) c, the extrusive magma cools so quickly so the mineral
grains don’t have time to grow.
In granite we can find visible grains. Rhyolite is the volcanic
equivalent of granite where we find the same composition but the
grains are so fine grained that can’t be visible.
66) A, high viscosity and dissolved gases
67) c, Pacific