A volcano is an opening on Earth's surface where magma escapes from
Magma is a molten mixture of rock-forming substgances, gases, and
water from the mantle
Magma that reaches Earth's surface is called lava.
The constructive force of volcanoes adds new rock to existing land and forms new islands.
volcanoes occur near Earth's plate boundaries and they form belts.
Generally form in subduction zones and divergent plate boundaries, such as the mid-ocean ridge.
The Ring of Fire, a belt that consists of many volcanoes, rims the Pacific Ocean.
Volcanoes at Converging Boundaries
Oceanic crust subducts under the continent.
The subducting material melts, rises, and pushes through the continental crust, forming a volcano.
Over thousands of years, the volcano may build into huge mountains.
Oceanic crust subducts under less dense oceanic crust.
The subducting material melts, rises, and pushes through the less dense oceanic crust, forming a volcano.
Over thousands of years,
the volcano may build beneath the ocean floor.
Eventually, it may become so large that it protrudes above the water and form an island.
When a chain of islands form in this manner, it is called an island arc.
A hot spot
is an area where magma from deep within the mantle melts through the crust.
If in the ocean floor, it can gradually form a series of volcanic mountains. (Hawaii)