Volcanoes Cheryl Jones Introduction Pacific Ring of Fire
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Volcanoes Cheryl Jones Introduction Pacific Ring of Fire Types of Volcanoes Quiz 1 Cinder Cones Volcanoes Video Composite Volcanoes
Introduction What is a volcano? Ø Volcano =Roman god of blacksmithing. Ø Formed from continental plates uplift and erosion. • Magma – molten rock under the earth • Lava – molten rock on the surface of the earth Ø Magma shoots out the vents ØVolcanoes also have different types of ash and lava. Ø 10 % are in the U. S.
Types of Volcanoes Ø Three main volcanoes Ø Different speeds or flows (viscosity) of the lave form different volcanoes Ø Ratio of ash and magna determines lava viscosity Ø Shield Volcanoes (most easy flowing)- lava flows great distances, gentle Ø Creates very wide volcanoes, shape – warriors shield slopes.
Cinder Cones Volcanoes Ø Cinder Cones (Bowl-Shaped Craters) Ø The viscous (thickest) lava piles up around the volcanic vent Ø Lava falls as cinders, flows far through lava channels Ø Steep with straight sides ØParicutin Volcano in Mexico, 100 square feet of ash
Composite Volcanoes Composite (stratovolcanoes) Volcanoes Ø Approximately 50% ash and 50% lava. ØAsh is loose ØThe lava in this volcano does not flow very fast ØLay dormant for hundreds of years ØOften have snow cap Mount Saint Helen
Pacific Ring of Fire Ø Is an arc stretching from New Zealand , Asia, Alaska, North & South America Ø 75% of the worlds active and dormant volcanoes are here Ø Earthquakes are frequent Ø Magma breaks thru melting plates, volcanoes form Ø Magma resistant to flow, eruptions are violent
What did the word Volcano refer to in ancient times?
