Volcano Questions...?

i cant find the answer to these, please help





1)Which type of landform develops at plate boundaries where one oceanic plate descendes beneath another?


a) rift valley


b) lava plateau


c) volcanic island arc


d) mountain ranges frmed by batholith











2) Most intraplate volcanic activity occurs where ____.


a) hot mantle plumes rise toward the surface within a plate.


b) oceanic plate diverge


c) hot magma descends into the mantle under a plate


d) oceanic and continental plates converge.|||1) (c) volcanic island arc





When an oceanic plate is forced beneath another into the Earth, it is called subduction. The descending (subducting) plate displaces magma from the mantle and forces it upwards, resulting in a deep-ocean trench and an arc of volcanoes (which are your volcanic islands) on the upper (overriding) plate along the trench.





2) (a) hot mantle plumes rise toward the surface within a plate





First of all, "intraplate" means "within a plate", so the answer cannot be (b) or (d), as those occur at plate boundaries. For (c), this does not ordinarily happen, as hot magma is less dense than the crust and surrounding mantle (which is why it rises in the first place). Now as for the correct answer (a), this is what is known as a hotspot, where unusually hot magma rises up through a plate, causing volcanism on the plate surface. The plate moves over the stationary mantle plume, creating a trail of evidence of volcanic activity. Examples include the Hawaiian Islands and Yellowstone.





Hope this helps.