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Volcanism is the eruption of magma to the surface of a planet. Molten rock wells up through a vent in the planet's mantle, spewing lava, gases and volcanic material into the surrounding area. Over time, this material hardens and accumulates, creating cone-shaped volcano...


Volcanic islands form over hot spots, which occur when tectonic plate movement allows magma from the Earth's core to erupt. As the volcano continues to erupt and cool, an island is formed.


Volcanic glass is typically called obsidian and is formed when viscous lava is rapidly cooled. This material contains between 65 to 80 percent silica and has a low water content. Obsidian is slightly more durable than window glass and possesses a glassy luster.


Volcanic mountains form as lava oozes forth from cracks in the earth. The lava builds up around the area where the eruption occurred. Layers build upon layers and over a period of time, a volcanic mountain forms.


A volcanic neck, also called a lava neck or volcanic plug, is a cylindrical-shaped volcanic landform created when magma hardens inside the vent of a volcano, according to the University of Wisconsin. Examples of volcanic necks include Devil's Tower in Wyoming, Lizard He...


Popular volcanic mountain names are Mount St. Helens in the United States mainland, Mauna Loa in Hawaii, Mount Rainier in Washington, Mount Edziza in British Columbia and Hoodoo Mountain in Canada. Many of the highest volcanoes are located in Chile and Argentina, such a...


A volcanic eruption is the expulsion of magma and gas from the Earth's interior. Most current volcanic eruptions are the result of one of three eruption mechanisms.


A volcanic hotspot is an area in the earth’s mantle in which thermal plumes provide the necessary heat and magma for volcanic activity over a long period, explains the U.S. Geological Service. These hotspots are the basis for the creation of land, including the Hawaiian...


Volcanic eruptions occur when magma builds up beneath the Earth's crust and forces its way to the surface. Natural vents in the crust allow magma passage to the surface, and eruptions occur when the magma that forms is less dense than the material above it, causing it t...


A volcanic neck forms when lava inside a caldera cools after magma stops feeding the mountain, and then the outside of the extinct volcano erodes after millions of years. The cooled lava remains intact because it is harder than the surrounding rock that eroded. Perhaps ...