Volcanoes

1. Volcanoes By: Paige Holmes 3/16/10

2. Shield Volcano Shield volcanoes are wide, gentle sloping mountains. A shield volcano created the Hawaii Islands. Thin layers of lava pour out of a vent and harden on top of previous layers. This lava creates shield volcanoes.

3. CompositeVolcano Composite volcanoes are both quiet and explosive eruptions. They are tall, cone-shaped mountains. Central vent Crater Layers of lava, ash, cinder, and bombs alternate to make a composite volcano. Mount St. Helens in Washington is a composite volcano Ash layers Lava layers Ash layers Lava layers

4. Cindercone When cinders erupt from the volcanic neck, they pile up around the vent and form a hill. A steep, cone-shaped hill or mountain. If lava is thick and stiff it may produce ash, cinder, and bombs.

5. Caldera The hole of a caldera is filled with pieces of the volcano that has fallen in. A huge hole left by the collapse of a volcanic mountain is called a caldera. It may have a lake in the middle of it. When an enormous eruption happens and empties all the magma it turns in to a caldera

6. Hotspringsandgeysers Hot spring Heat source Hot springs form when underground heated by a nearby body of magma rises to the crust and collects in a natural pool. Geyser A geyser is a fountain of water and steam that erupts from the ground. The water from hot springs may contain dissolved gases and other substances from deep within Earth.

7. Volcanic Necks, Dikes, and Sills Volcanic necks Volcanic necks look like a giant tooth stuck in the ground. It forms when magma hardens in a volcano’s pipe. The softer rock around the pipe wears away, exposing the hard rock of the volcanic neck. Dikes Magma that forces itself across rock layers hardens into a dike. Volcanic neck Sill Dike Sills A sill is when magma squeezes between layers of rock.