Volcanoes By Kiley Layman 3/11/10

1. Volcanoes By Kiley Layman 3/11/10

2. Shield Volcanoes Shield volcanoes are broad, gently sloping mountains that occur when thin layers of lava pour out of a vent and harden on top of previous layers. This type of volcano is what created the Hawaiian Islands.

3. Composite Volcano Composite volcanoes are tall, cone-shaped volcanic mountains that are made when lava, ash, cinders, and bombs harden on the mountainside and build over time. Some examples of composite volcanoes are Mount Fiji in Japan and Mount St. Helens in Washington state. Main vent Side vent Layers of Lava and Ash

4. Cinder Cone Volcano A cinder cone volcano is a cone-shaped volcanic hill or mountain that can be very steep. This type of volcano produces very thick, stiff lava that turns into ash, cinders, and bombs.

5. Caldera Geyser Groundwater When an enormous eruption empties the magma chamber, the mountain becomes a hollow shell. The top of the mountain collapses inward. This creates a caldera. Sometimes, water may fill up the hole and create a lake. Magma Chamber

6. Hot Springs and Geysers Two examples of volcanic activity that don’t involve lava are geysers and hot springs. Groundwater heated by magma which rises to the surface and collects in a pool causes a hot spring. Geysers are formed when rising hot water and steam become trapped underground in a narrow crack. The pressure builds and the water sprays above the surface. Geyser Hot spring groundwater Magma chamber

7. Did You Know? Volcanic neck Dike Sill • Some other parts of a volcano are the volcanic neck, dike, and sill. • A volcanic neck is formed when magma hardens in a volcano’s pipe. The softer rock crumbles and reveals the hardened magma. • A dike occurs when magma forces itself across rock layers and hardens. • A sill is formed when magma squeezes itself between layers of rock.