GEOL 120 1st Edition Lecture 7Outline of Last Lecture I. FreezeII. MagmaIII. LavaIV. MeltV. Viscosity (noun)VI. Igneous processesVII. Intrusive igneous rocksVIII. Extrusive igneous rocksIX. Melting RocksX. Misconception about MeltingOutline of Current Lecture I. VolcanoesII. Eruptions produce three main thingsIII. Secondary effects of eruptions includeIV. ViscosityV. Lava CompositionsVI. Basaltic Lava FlowsVII. Characteristics of mafic Lava FlowsCurrent LectureI. Volcanoesa. Vents in the lithospherei. Magma can rise to the surfaceb. Activei. Erupted recently ii. Dormant1. Not erupted for 10,000 yrs, but amy erupts againiii. Extinct 1. Volcanoes that will never erupt againc. Caused by tectonic activityi. RiftingThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. Subductioniii. Hot spotsII. Eruptions produce three main thingsa. Lava flowi. Can be thin and runny or thick and stickyii. Flow style depends on viscosity1. Composition, primarily silica content2. Temperature3. Gas content4. Crystal contentb. Pyroclastic debrisc. GasIII. Secondary effects of eruptions includea. Volcanic mud flows: laharsb. Weather/climate change IV. Viscositya. Describes resistance flowb. Primarily controlled by compositionc. Felsic (light)i. High viscosityd. Mafic (dark)i. Low viscositye. Temperature/Crystal contenti. Cooler lava1. More crystalsii. Warmer ala1. Less crystalsV. Lava Compositionsa. Lavas with high silica & low Fe and Mg are called:i. Silicic, felsic, or rhyoliticb. Lavas with lower silica & higher Fe/Mg are called:i. Mafic or basalticc. Lavas with moderate silica, Fe, and Mg are called:i. Intermediate or andesiticVI. Basaltic Lava Flowsa. A’a’ (ah-ah) i. Word describing solidifies with a jagged, sharp, angular textureb. Forms when hot flowing basalt cools and thickensc. With flow, lava crumbles into shards and fragmentsd. Lava Tubesi. Lava often travels in lava tubes1. Provides and insulated pathway that allows long-distance flowVII. Characteristics of mafic Lava Flowsa. Cant ravel long distanceb. Have unique properties for groundwater
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