Presentation is loading. Please wait.

Presentation is loading. Please wait.

Ch. 18 Volcanoes. Ch. 18 Vocabulary Viscosity Tepha Vent Hot Spot Caldera Cinder-Cone Volcano Composite Volcano Pyroclastic Flow Shield Volcano Crater.

Similar presentations


Presentation on theme: "Ch. 18 Volcanoes. Ch. 18 Vocabulary Viscosity Tepha Vent Hot Spot Caldera Cinder-Cone Volcano Composite Volcano Pyroclastic Flow Shield Volcano Crater."— Presentation transcript:

1 Ch. 18 Volcanoes

2 Ch. 18 Vocabulary Viscosity Tepha Vent Hot Spot Caldera Cinder-Cone Volcano Composite Volcano Pyroclastic Flow Shield Volcano Crater

3 Magma Proves that earth is geologically active Magma formed deep within earths surface  Temperatures must be high enough to melt rock o C  Temperatures increase with depth  Pressure increase with depth  Increase Pressure – Decrease melting point B/C Magma is less dense than surrounding rock, Magma rises to surface

4 Magma Composition Viscosity  Resistance to flow  Hotter the magma, lower the viscosity Silica content  Determines viscosity  High content – high viscosity Water content  High amounts of water will evaporate, build pressure  More explosive Three Types of Magma

5 Magma Types Basaltic  Low Viscosity (50% Silica)  Quiet Eruptions Andesitic  Intermediate Viscosity (60% Silica)  Intermediate Eruptions Rhyolitic  High Viscosity (70% Silica)  Great Eruptions

6 Volcano Locations: Ring of Fire

7 Anatomy of a Volcano Vent  Magma reaches the surface and lava erupts out of a vent  Lava solidifies and builds up mountain around vent  Cone (1 km wide) or Caldera (50 km wide)

8 Types of Volcanoes Shield  Broad gently sloping sides  Layer upon layer of basaltic lava accumulation (non-explosive)  Low viscosity

9 Types of Volcanoes Cinder Cone  Material exploded high into the air and comes back to earth  Steep side from explosive eruptions  More viscous lava contains more gases which fuel more explosive eruptions

10 Types of Volcanoes Composite  Volcanic fragments and lava eruptions – most common  Contains large amounts of silica, water, and gases  Potentially dangerous to people and environment

11 Other locations for Volcanoes Hot Spots  Located away from plate boundaries  High temperature mantle plumes rise towards the surface  Hawaiian Islands


Download ppt "Ch. 18 Volcanoes. Ch. 18 Vocabulary Viscosity Tepha Vent Hot Spot Caldera Cinder-Cone Volcano Composite Volcano Pyroclastic Flow Shield Volcano Crater."

Similar presentations


Ads by Google