Part I Fill in the blanks with the words you have heard. Listen to part of a lecture in an Earth Science class. The class has been discussing volcanoes. Okay. We know the Earth’s (1)_____ , the crust, is made up of tectonic plates, and that these huge slabs of rocky crust are slowly sliding over or under or past each other. And we said that most of the world’s volcanoes occur at the boundaries of these tectonic plates . W here you have hot molten rocks squeezing up through gaps between the plates . But some volcanoes occur not at the (2)_____ , but in the middle of a continental or oceanic plate.The Hawaiian islands, for example, are thousands of kilometers away from any plate boundary, and yet you have (3)_____ amounts of magma, molten rock or lava, flowing up through the earth’s crust, which means, of course,that (4)_____ activity there can’t be explained simply by plate tectonics.So, how do we explain these volcanic anomalies, these exceptions to the general rule? Well, back in (5)_____ , a geophysicist by the name of Wilson came up with a hot spot theory to explain how this particular type of volcanic activity can occur and can go on for maybe tens or even hundreds of millions of years.