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Southern Miss GLY 101 - Volcanoes and Materials that Extrude during Eruptions

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GLY 101 1st Edition Lecture 7Outline of Last Lecture I. Matter and MaterialsOutline of Current Lecture II. A. VolcanoesB. Quiescent vs. Explosive EruptionsIII. A. Materials extruded during an eruptionB. Pyroclastic MaterialsCurrent LectureII. Volcanoes-magma is molten rock that usually contains some crystals and varying amounts of dissolved gas. Erupted magma is called lava- temperature, composition, and dissolved gasses are primary factors that affect the behavior of magma.-viscosity or magma’s mobility is determined by these three factorsB. Quiescent vs. Explosive Eruptions- Quiescent Hawaiian type eruptions involve very fluid basaltic lavas that are triggered by the arrival of a new batch of molten rock into a near-surface magma chamber.- These can usually be detected because the summit of the volcano inflates and rise before the eruption. The rise can take months or even years before it eruptsExplosive eruptions These 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.- when magmas expel particles of fragmented lava and gases at supersonic speeds that evolve into buoyant plumes this is called eruption columns III. Materials extruded during an eruption-lava is one of the materials that extrude during an eruption-basaltic (mafic) is the majority of lava on earth at 90% -andesitic lava accounts for less than 10%-rhyolitic(felsic) lava make up as little as 1% of the total - the flow of basaltic lava is very fluid, the rhyolitic moves slow and andesitic shares characteristics between these two. - basaltic magma generates 2 types of lava flows(known by Hawaiian names):1.aa (ah-ah)- have surfaces of rough jagged blocks with dangerously sharp edges and spiny projections2.pahoehoe (pah-hoy-hoy)-mean one who can walk; exhibit smooth surfaces that resemble twisted ropes-pahoehoe lava is hotter and more fluid than aa flows. pahoehoe flows can change into aa flows but aa flows can not change into pahoehoe flows.-pahoehoe flows often develop cave like tunnels called lava tubes. -andesitic and rhyolitic magmas tent to generate short thick flows, the upper surface consists of massive, detached blocks. This is referred to as block lava.B. Pyroclastic Materials-pyroclastic materials are pulverized rock and lava fragments form the vent; this happens when volcanoes erupt energetically.- also known as tephra-volcanic ash is produced when gas-rich viscous magma erupts explosively -larger pyroclasts that range in size from 2-64 millimeters are known as lapilli(little stones)- lapilli is also referred to as cinders- particles larger than 64 millimeters are called blocks. when they are ejected as incandescent lava they are called


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