Reading Comprehension Sheet - Volcanoes And Plate Tectonics (Page 2 of 2) in pdf

Reading Comprehension Sheet - Volcanoes And Plate Tectonics Page 2

Through subduction, the older, denser Ocean plate sinks

beneath the less dense plate at a deep-ocean trench into the

mantle. Some of the rock above the subducting plate melts and

forms magma. Because the magma is less dense than the

surrounding rock, it rises toward the surface. Eventually, the

magma breaks through the ocean floor, creating volcanoes/

volcanic mountains. With Ocean-Ocean interaction, the

resulting volcanoes create a string of islands called an island

arc. Volcanic mountains also occur where an oceanic plate is

subducted beneath a continental plate.

O-O Convergent Subduction

Trench forms at collision sight on large ocean plate

Volcanic arc forms along less dense, smaller ocean plate

Ex. Japan, New Zealand, Indonesia, Philippines, Aleutians,

Caribbean Islands

O-C Convergent Subduction

Trench forms at collision sight along ocean plate

Volcanic Mountain range forms along continental plate

Ex. Andes mountains in SA, Cascade Mountain range- NW US

Some volcanoes result from “hot spots” in Earth’s mantle. A hot

spot is an area where material from within the mantle rises and

then melts, forming magma. A volcano forms above a hot spot

when magma erupts through the crust and reaches the surface.

A hot spot in the ocean floor can gradually form a series of

volcanic mountains. The Hawaiian Islands formed one by

one over millions of years as the Pacific plate drifted over a hot spot.

Hot spots can also form under the continents. Yellowstone

National Park in Wyoming marks a hot spot under the North

American plate.

Reading Comprehension Sheet - Volcanoes And Plate Tectonics Page 2