GLG 112 1st Edition Lecture 26Outline of Last Lecture III. Composite ConesA. AppearanceB. FormationC. LocationsD. ExamplesOutline of Current Lecture IV. Volcanic DomesA. AppearanceB. FormationC. LocationsD. ExamplesV. CalderasA. AppearanceB. FormationCurrent LectureVolcanic DomesAppearance- No obvious crater/peak- Rough surfaceo Made out of lumpy, high viscosity magma- Fairly small (smaller to larger than a cinder cone)- Grey color (lighter than shield volcanoes or cinder cones)o Has a higher silica content- Dome-shapedo Fairly steep, uneven slopesFormation- Magma=Dacite (between intermediate and felsic)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.- Effusive- Has the consistency of toothpaste (not gel)- Low volatile contento Pressure builds and eventually explodes (at any moment)o It traps the gas- Age (timing)o Small = hourso Big = 1000s of yearsLocations- On continents (where the continental lithosphere is thicker)o Continental hot spotso Subduction zones (oceanic/continental)- Commonly associated with composite cones and calderas- Can also be isolatedExamples- Dome in the crater of Mt. St. Helens- Mt. EldenCalderasAppearance- Big hole in the ground- Size is anywhere from large to hugeFormation- Magma=felsic (rhyolite)- High volatile content- Super explosive- “super volcano” is the term coined by the media- Ultra-Plinian
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