Earth’s surface consists of rigid plates that are constantly shifting and jostling one another. Plate movements are the surface expressions of motions in the mantle—the thick shell of rock that lies between Earth’s crust and its metallic core. Although the hot rock of the mantle is a solid, under the tremendous pressure of the crust and overlying rock of the mantle, it flows like a viscous liquid. The mantle’s motions, analogous to those in a pot of boiling water, cool the mantle by carrying hot material to the surface and returning cooler material to the depths. When the edge of one plate bends under another and its cooler material is consumed in the mantle, volcanic activity occurs as molten lava rises from the downgoing plate and erupts through the overlying one.
Most volcanoes occur at plate boundaries. However, certain “misplaced” volcanoes far from plate edges result from a second, independent mechanism that cools the deep interior of Earth. Because of its proximity to Earth’s core, the rock at the base of the mantle is much hotter than rock in the upper mantle. The hotter the mantle rock is, the less it resists flowing. Reservoirs of this hot rock collect in the base of the mantle. When a reservoir is sufficiently large, a sphere of this hot rock forces its way up through the upper mantle to Earth’s surface, creating a broad bulge in the topography. The “mantle plume” thus formed, once established, continues to channel hot material from the mantle base until the reservoir is emptied. The surface mark of an established plume is a hot spot—an isolated region of volcanoes and uplifted terrain located far from the edge of a surface plate. Because the source of a hot spot remains fixed while a surface plate moves over it, over a long period of time an active plume creates a chain of volcanoes or volcanic islands, a track marking the position of the plume relative to the moving plate. The natural history of the Hawaiian island chain clearly shows the movement of the Pacific plate over a fixed plume.
【Vocabulary】
Rigid (adj.)剛硬的
Plate (n.)板塊
Jostle (V.)擠/推撞
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Type: 自然科學解釋類/火山形成的兩種原因
P1: 大概介紹一下地球板塊的組成，重點一帶出來-->火山通常形成在板塊邊緣，"One plates bends under another, volcanic activity…"
P2: However,帶出文章重點二，開始介紹某些不在板塊邊緣形成的火山，在地球內部深層形成的火山。
最後舉個例子，帶出夏威夷島的演化形成就是第二種火山形成原理的例子。
Q22 主旨題
整篇文章沒有出現正反論點，第二段的However可以看出就是在講另外一種火山的形成原理。
(D) Two different kind of
Q23 細節題 (這篇因為太多生字所以我跳著看，只看有轉折語或關鍵字)
定位句"Because the source of a hot spot remains fixed while a surface plate moves over it, over a long period of time an active plume creates a chain of volcanoes or volcanic islands, a track marking the position of the plume relative to the moving plate."
(A) 不知道在說甚麼....感覺文章也沒細講...刪
(B) "differ from other in age "呼應定位句裡面的" Over a long period of time"
(C) a plate boundary 是傳統火山形成方法，跟題目問的mantle plume 火山不同種...離題
(D) 事後諸葛把文章看完，知道這個選項的內容錯了，但當下因為覺得關鍵點在"over a period of time"，所以看到 (B)就賭下去了，但當下這個選項刪的是心虛的。
(E) chemical
Q24 舉例夏威夷火山的原因
定位句 最後一句" The natural history of the Hawaiian island chain clearly shows the movement of the Pacific plate over a fixed plume."
因為關鍵字抓Clear shows the movement所以不是提供一個歷史記錄的example的BCD全刪
(A) 講的也不是plume這種類型的火山
(E) 正解
Q25 細節題 定位句
"The surface mark of an established plume is a hot spot—an isolated region of volcanoes and uplifted terrain located far from the edge of a surface plate."
hot spot>>surface mark of a plume>>(E)選項中唯一有提到plume的>>賭了!
事後諸葛，其他選項也都錯..
(A) untapped
(B) edge of a plate
(C) 無關
(D) 無關
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