Presentation on theme: "Volcanoes By Seth Linford, 3/11/10. Shield Volcano Shield volcanoes are seen as a gentle, sloping mountain. Most examples are in the ocean, such as the."— Presentation transcript:
Volcanoes By Seth Linford, 3/11/10
Shield Volcano Shield volcanoes are seen as a gentle, sloping mountain. Most examples are in the ocean, such as the Hawaiian Islands. They are mostly built up over time by quiet eruptions. This is what produces the sloping mountains and islands. Kilauea in Hawaii
Composite Volcano Composite volcanoes are named for their alternating layers of lava and ash. They have these layers because they spew both cinders and bombs with ash, and lava in violent eruptions. They are tall and cone shaped like the Cinder Cone Volcano. Mount Fuji in Japan
Cinder-Cone Volcano Cinder Cone volcanoes are formed when a explosive eruption makes cinders and bombs, in addition to lava, pile up and form a cone shape around the vent. The can be deadly when they erupt, because the are always explosive.
Caldera Old magma chamber Crater Lake is a well known caldera. Calderas are huge crater left behind from a massive eruption. They are formed when the eruption totally empty the volcano, and then the sides collapse. Or the eruption is so big it blows the whole mountain up. The whole Yellowstone area is a caldera from a super volcano.
Hot Springs and Geysers Geyser Magma Heater Hot Springs Geysers and Hot Springs occur when magma gets close to the surface, but doesn’t break through. Hot springs heat up to 95 F and way more. Geysers happen when the water boils, and gets so hot that it builds up pressure in its little hole, then it shoots out its vent.
Types of Lava There are two types of lava, Aa and Pahoehoe. Aa forms when the lava is slow moving and cool. It forms big, jagged, chunks. Pahoehoe forms when the lava is hot and fast flowing. It cools as a blob with a rippled surface, like hardened mercury.