นักวิจัยส่วนใหญ่ are in agreement that a cylindrically shaped upwelling of hot rock,called a mantle plump, is located beneath the island of Hawaii. As the hot, rocky plump ascends through the mentle, the confining pressure drops, which triggers partial melting. (This process, called decompression meilting, is discussed in Chapter9.)The surface manifestation of this activity is hot spot, an area of volcanism, high heat flow, and crustal uplifting that is a few hundred kilometers across