Homework  Metamorphic rock lab due Monday  Read section 9.3  Q’s 1-4 on pg 201

Definitions Section 9.2

Magma and Erupted Materials  Viscosity: A substance’s resistance to flow (high viscosity = honey, low = water)  Lava: Magma that reaches Earth’s surface

 Pahoehoe: Solidified basaltic lava flow on land that has formed with smooth, ropelike surfaces  Aa: A solidified basaltic lava flow on land that has formed with rough, jagged surfaces

 Lahar: a fast-moving mudflow that occurs when heat of a volcano melts the snow and ice on top of a volcano  Pillow Lava: Lava that cools underwater, taking on a distinctive pillow-like shape as it hardens

 Pyroclastic material: solid rock fragments that are ejected during a volcanic eruption  Pyroclastic flow: A dense, superheated cloud of gases and pyroclastic materials that moves rapidly downhill from an eruption volcano

Felsic and Mafic Magmas  Felsic (Feldspar Silica) magma: high silica, low density, light-colored, slow moving and typically come out of explosive volcanoes  Mafic (Magnesium ferric) magma: low silica, high density, more fluid, darker in color and flow more easily. Usually flows smoothly onto the surface

Characteristics of Magma

Please copy this chart in your notes Basaltic Magma Andesitic Magma Rhyolitic Magma Silica Content Gas Content Viscosity Type of Eruption Melting Temp. Location Example

Basaltic Magma Andesitic Magma Rhyolitic Magma Silica Content Least (~50%)Intermediate (~60%) Most (~70%) Gas Content Viscosity Type of Eruption Melting Temp. Location Example

Basaltic Magma Andesitic Magma Rhyolitic Magma Silica ContentLeast (~50%)Intermediate (~60%)Most (~70%) Gas ContentLeastIntermediateMost Viscosity Type of Eruption Melting Temp. Location Example

Basaltic Magma Andesitic Magma Rhyolitic Magma Silica ContentLeast (~50%)Intermediate (~60%)Most (~70%) Gas ContentLeastIntermediateMost ViscosityLeast viscousIntermediateMost viscous Type of Eruption Melting Temp. Location Example

Basaltic Magma Andesitic Magma Rhyolitic Magma Silica ContentLeast (~50%)Intermediate (~60%)Most (~70%) Gas ContentLeastIntermediateMost ViscosityLeast viscousIntermediateMost viscous Type of Eruption Rarely explosive Sometimes explosive Usually explosive Melting Temp. Location Example

Basaltic Magma Andesitic Magma Rhyolitic Magma Silica ContentLeast (~50%)Intermediate (~60%)Most (~70%) Gas ContentLeastIntermediateMost ViscosityLeast viscousIntermediateMost viscous Type of EruptionRarely explosiveSometimes explosiveUsually explosive Melting Temp. HighestIntermediateLowest Location Example

Basaltic Magma Andesitic Magma Rhyolitic Magma Silica ContentLeast (~50%)Intermediate (~60%)Most (~70%) Gas ContentLeastIntermediateMost ViscosityLeast viscousIntermediateMost viscous Type of EruptionRarely explosiveSometimes explosiveUsually explosive Melting Temp.HighestIntermediateLowest LocationRifts, oceanic hot spots Subduction Boundaries Continental hot spots Example

Basaltic Magma Andesitic Magma Rhyolitic Magma Silica ContentLeast (~50%)Intermediate (~60%)Most (~70%) Gas ContentLeastIntermediateMost ViscosityLeast viscousIntermediateMost viscous Type of EruptionRarely explosiveSometimes explosiveUsually explosive Melting Temp.HighestIntermediateLowest LocationRifts, oceanic hot spotsSubduction BoundariesContinental hot spots ExampleKilauea, Hawaii Mount St. Helens, Washington Yellowstone caldera, Wyoming

Goofy but informational! Mt. Etna Goofy but informational! Mt. Etna