Magma is a molten mixture of rock forming substances, gases, and water from the mantle. After lava has cooled , it forms solid rock. The lava released during volcanic activity builds up Earth's surface. Volcanic activity is a constructive force that adds new rock to existing land and forms new islands. In a shield volcano, repeated lava flows during quiet eruptions gradually build up a broad, gently sloping volcanic mountain.
Shield volcanoes are more flat than all of the other volcanoes.
They can also be the largest of all volcanoes. The Hawaiian Islands are a series of shield volcanoes. When cinder cones erupt explosively from a volcanic vent, they pile up around the vent, forming a cone-shaped hill called a cinder cone. Composite are the tallest of the three forms of volcanoes. They also have the biggest explosion when erupting.