3 MagmaProves that earth is geologically activeMagma formed deep within earths surfaceTemperatures must be high enough to melt rock oCTemperatures increase with depthPressure increase with depthIncrease Pressure – Decrease melting pointB/C Magma is less dense than surrounding rock, Magma rises to surface
4 Magma Composition Viscosity Silica content Water content Resistance to flowHotter the magma, lower the viscositySilica contentDetermines viscosityHigh content – high viscosityWater contentHigh amounts of water will evaporate, build pressureMore explosiveThree Types of Magma
7 Anatomy of a Volcano Vent Cone (1 km wide) or Caldera (50 km wide) Magma reaches the surface and lava erupts out of a ventLava solidifies and builds up mountain around ventCone (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 earthSteep side from explosive eruptionsMore viscous lava contains more gases which fuel more explosive eruptions
10 Types of Volcanoes Composite Volcanic fragments and lava eruptions – most commonContains large amounts of silica, water, and gasesPotentially dangerous to people and environment
11 Other locations for Volcanoes Hot SpotsLocated away from plate boundariesHigh temperature mantle plumes rise towards the surfaceHawaiian Islands
Your consent to our cookies if you continue to use this website.