A volcano is a feature of Earth’s crust that allows molten rock from beneath the crust to reach the surface. This gorgeous volcanic cone is Shishaldin, a volcano on Unimak Island, Alaska.
A volcanic cone is a hill-shaped landform that forms around a volcano. Volcanic cones can be steep or gently sloping depending on the type of eruption that forms them.
The steepest cones form around cinder cone volcanos. Cinder cones form from ash and magma cinders--partly-burned, solid pieces of magma, that fall to the ground following a volcanic eruption. This type of eruption contains little lava, as the magma hardens and breaks into pieces during the explosion. As a result, cinder cone volcanoes tend to be smaller than other types of volcanoes. Italy’s Mt. Vesuvius is a famous cinder cone volcano.
In contrast, shield volcanoes are characterized by a large, broad cone with sides sloping gently away from the center. The lava that erupts from these volcanoes is a thin liquid that slowly emerges from the center of the volcano as well as from cracks in its sides. The lava spreads in a thin layer before cooling. Hawaii’s Mauna Loa is a famous example of a shield cone volcano.
A third type of volcanic cone is a composite cone. Composite cone volcanoes are also called stratovolcanoes. They form when different types of eruptions deposit different materials around the sides of a volcano. Alternating eruptions of volcanic ash and lava cause layers to form. Over time these layers build up. The result is a cone that has a gentler slope than a cinder cone but is steeper than a shield volcano. Washington state’s Mt. St. Helens is an example of a composite cone volcano.
A volcano is a feature of Earth’s crust that allows molten rock from beneath the crust to reach the surface. This gorgeous volcanic cone is Shishaldin, a volcano on Unimak Island, Alaska.
Photograph by J. Baylor Roberts, National Geographic
hill created by tiny bits of lava blown out of a volcano and fallen down around the volcanic vent. Also called a scoria cone.
release of material from an opening in the Earth's crust.
active volcano in the U.S. state of Washington. (2,549 meters/8,364 feet)
active volcano in southwest Italy. (1,190 meters/3,900 feet)
large, gently sloping volcano made from fluid lava.
steep volcano made of hardened lava, rock, and ash. Also known as a composite volcano.
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Volcano
According to the United States Geologic Survey, there are approximately 1,500 potentially active volcanoes worldwide. Most are located around the Pacific Ocean in what is commonly called the Ring of Fire. A volcano is defined as an opening in the Earth's crust through which lava, ash, and gases erupt. The term also includes the cone-shaped landform built by repeated eruptions over time. Teach your students about volcanoes with this collection of engaging material.
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Volcano
According to the United States Geologic Survey, there are approximately 1,500 potentially active volcanoes worldwide. Most are located around the Pacific Ocean in what is commonly called the Ring of Fire. A volcano is defined as an opening in the Earth's crust through which lava, ash, and gases erupt. The term also includes the cone-shaped landform built by repeated eruptions over time. Teach your students about volcanoes with this collection of engaging material.