优化指导13-14学年高二英语课件（人教版，选修6）unit5Thepowerofnature-.ppt

;【问题导读】 Read the text and try to tell if these sentences are True( T ) or False(F)． 1．Volcanic eruptions are super-natural phenomena in the eyes of ancient people’s.(　　) 2．Some of the finer ejected materials may be carried by the wind only to fall to the ground many miles away.(　　) 答案：1.T　2.T;古罗马时期，人们看见火山喷发的现象，把这种山体燃烧的原因归之为火神武尔卡发怒，“火山”一词的英文名称—Volcano由此而来。火山爆发喷出的大量火山灰和暴雨结合形成泥石流，能冲毁道路、桥梁、淹没附近的乡村和城市，使得无数人无家可归。但火山资源的利用也可以给我们的生活带来便利。;The word“volcano”comes from the little island of Volcano in the Mediterranean Sea off Sicily.Centuries ago，the people living in this area believed that Volcano was the chimney of the forge of Volcan－the blacksmith of the Roman gods.They thought that the hot lava fragments and clouds of dust erupting from Volcano came from Volcan’s forge1 as he beat out thunderbolts2 for Jupiter，king of the gods, and weapons for Mars，the god of war.In Polynesia the people attributed3 eruptive activity to the beautiful but wrathful Pele，Goddess of Volcanoes，whenever she was angry or spiteful.Today we know that volcanic eruptions are not super-natural but can be studied and interpreted by scientists. ;Volcanoes are mountains，but they are very different from other mountains；they are not formed by folding and crumpling or by uplift and erosion4.Instead，volcanoes are built by the accumulation of their own eruptive products－lava，bombs (crusted over lava blobs)，ashflows，and tephra (airborne ash and dust)．A volcano is most commonly a conical hill or mountain built around a vent that connects with reservoirs of molten rock below the surface of the Earth.The term volcano also refers to the opening or vent through which the molten rock and associated gases are expelled.;Driven by buoyancy and gas pressure the molten rock，which is lighter than the surrounding solid rock，forces its way upward and may ultimately break through zones of weaknesses in the Earth’s crust.If so, an eruption begins，and the molten rock may pour from the vent as nonexplosive lava flows，or it may sh