Volcanoes Essay

Volcanoes
Summary: A summary of the three different types of volcanoes -- the composite volcano, the shield volcano, and the cinder cone volcano. All volcanoes have different shapes, sizes, and types of eruptions.
When magma beneath the Earth's surface is forced up through any opening in Earth's crust, it is called a volcano. Some pour or explode molten rock, ash, cinders, and poisonous gases. Volcanoes are also types of mountains made up of hardened layers of lava and cinders. There are three general types of volcanoes: the composite volcano, the shield volcano, and the cinder cone.
The composite volcano has the most powerful eruptions of all the volcanoes, Its steeply sloping cone is made up of alternating layers of cinders, ash, and lava. Gases that are trapped in silica rich magma cause eruptions switching between quiet flows of lava and violent eruptions of gas-rich lava. Mount St. Helens, Washington State and Japan's Mt. Fuji are examples of composite volcanoes. Mount St. Helens killed 57 people in less than 1 mintue on May 18, 1980!

Shield volcanoes are formed in the shape of a large round-like shield from lava flowing outward in all directions. These broad volcanoes with gently sloping sides are the world's largest volcanoes. They are made up of thick layers of lava. A shield volcano may erupt many times over a period of more than a million years. Mauna Loa, in Hawaii, is the world's largest active volcano. From the floor of the Pacific Ocean to its summit, Mauana Loa is about 9 km (6 mi) high. It's even higher than Mt. Everest!

A cinder con volcano is built from ashes, cinders, and rocks, that burst from Earth during a violent eruption. These particles fall back to the ground around the opening to form a cone. Cinder cones tend to be active for a short period of time, and then become inactive, so most are not taller than 300 m (about 1000 ft.). Cinder cones are very eruptive and mostly release ashes, though they are the smallest and most plentiful...