Chapter 9 (1) - Chapter 9 Volcano an erupting vent through...

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Chapter 9 Volcano: an erupting vent through which molten rock reaches the Earth's surface viscosity: resistance to flow - the more silica there is in the lava, the more viscosity there is a. basaltic lava: very little silica and thus very low viscosity. flows quickly and freezes into smooth glassy repo-like ridges. Hawaiians call it " pahoehoe" b. andesitic lava: some silica and thus, does not flow as easily as basaltic. flows like a jumble of rubble because as the outside solidifies, the inside moves and breaks up the outside c. rhyolitic lava: most silica and thus, most viscous. usually accumulated a lava dome above the vent Lava Dome: a dome-like mass of rhyolitic lava that accumulates above the eruption vent Volcanic Ash: during andesitic or rhyolitic eruptions, powerful explosions spray lava into the air forming droplets that instantly freeze into volcanic ash composed of tiny glass shards Pyroclastic Debris: all fragmental material erupted from a volcano a. Lapilli: pea to plum sized fragments. forms from low viscosity lava b. Blocks and Bombs: apple to refrigerator sized fragments. blocks are chunks of igneous rocks torn off the walls of the vent, bombs from when large lava blobs enter the air in molten state and solidify Tuff: ash mixed with lapilli Pyroclastic Flow:
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This note was uploaded on 02/01/2012 for the course GEOLOGY 100 taught by Professor Lepre during the Fall '11 term at Rutgers.

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Chapter 9 (1) - Chapter 9 Volcano an erupting vent through...

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