SOLVED

21) Which type of basaltic lava flow has its surface covered with sharp-edged, angular blocks and rubble? A) scoria B) pahoehoe C) pillow lava D) aa 22) Which one of the following statements concerning volcanic blocks and bombs is true? A) Blocks are broken fragments of solid rocks; bombs have smaller sizes than lapilli. B) Bombs are guided to Earth by laser beams; blocks fall anywhere. C) Bombs are ejected as magma lumps; blocks are ejected as solid fragments. D) Bombs and blocks are both smaller than lapilli and cinders. 23) ________ destroyed the city of St. Pierre, Martinique in 1902. A) Mudflows B) Basaltic lava flows C) Heavy ashfall D) A nueé ardente 24) Which one of the following statements concerning cinder cones is false? A) They are small volcanoes with fairly steep sides. B) They are built mostly or entirely during one eruptive cycle. C) The cinders and other pyroclastic particles are consolidated into welded tuff. D) The cinders most commonly are basaltic. 25) The Columbia Plateau in Washington and Oregon is ________. A) a flood basalt plateau B) a thick stack of welded-tuff layers C) a caldera filled with rhyolite lava flows D) a field of large stratovolcanoes 26) Which kind of eruptive activity is most likely to be highly explosive? A) lava flows from a large shield volcano on an oceanic island B) fissure eruptions feeding lava to flood basalt accumulations C) eruptions of big, continental margin, composite cones or stratovolcanoes D) lava flows from a large cinder cone complex 27) Which one of the following statements is not true? A) Melting temperatures of silicate rocks increase with increased pressure. B) Melting temperatures of silicate rocks are lowered by small amounts of water. C) Basalt magmas in general have higher temperatures than rhyolite magmas. D) When magma reaches the surface, its dissolved gas content increases. 28) Which kind of volcanism is typical of mid-oceanic ridge systems? A) explosive; composite cones B) submarine; basaltic lava flows C) fissure eruptions; flood basalts fields D) explosive; rhyolitic, pyroclastic flows 29) Kilauea and Mauna Loa are ________. A) explosive, rhyolitic volcanoes B) andesitic stratovolcanoes C) basaltic shield volcanoes D) small, basaltic cinder cones 30) Mount St. Helens is ________. A) a basaltic cinder cone B) an explosive stratovolcano C) a basaltic shield volcano D) a small, welded tuff cone