6th grade Science

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Due: Tuesday November 4

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19 thoughts on “6th grade Science

  1. http://pubs.usgs.gov/gip/volc/cover2.html

    If you look at the bottom, it will have links to learn about each subject part. It has a lot of info. It also has something about the volcanoes on Mars and geysers. Did you know that 2/3 of all the geysers in the world are at Yellowstone National Park? I learned that when I went there.

  2. Volcano WorldBrings modern and near real-time volcano information.
    volcano.oregonstate.edu

    -that was the website i read for the volcanoes.

  3. Lava composition
    Pāhoehoe Lava flow at Hawaii (island). The picture shows few overflows of a main lava channel.
    The Stromboli volcano off the coast of Sicily has erupted continuously for thousands of years, giving rise to the term strombolian eruption ejecting lava bombs

    Another way of classifying volcanoes is by the composition of material erupted (lava), since this affects the shape of the volcano. Lava can be broadly classified into 4 different compositions (Cas & Wright, 1987):

    * If the erupted magma contains a high percentage (>63%) of silica, the lava is called felsic.
    o Felsic lavas (or rhyolites) tend to be highly viscous (not very fluid) and are erupted as domes or short, stubby flows. Viscous lavas tend to form stratovolcanoes or lava domes. Lassen Peak in California is an example of a volcano formed from felsic lava and is actually a large lava dome.
    o Because siliceous magmas are so viscous, they tend to trap volatiles (gases) that are present, which cause the magma to erupt catastrophically, eventually forming stratovolcanoes. Pyroclastic flows (ignimbrites) are highly hazardous products of such volcanoes, since they are composed of molten volcanic ash too heavy to go up into the atmosphere, so they hug the volcano’s slopes and travel far from their vents during large eruptions. Temperatures as high as 1,200 °C are known to occur in pyroclastic flows, which will incinerate everything flammable in their path and thick layers of hot pyroclastic flow deposits can be laid down, often up to many meters thick. Alaska’s Valley of Ten Thousand Smokes, formed by the eruption of Novarupta near Katmai in 1912, is an example of a thick pyroclastic flow or ignimbrite deposit. Volcanic ash that is light enough to be erupted high into the Earth’s atmosphere may travel many kilometres before it falls back to ground as a tuff.
    * If the erupted magma contains 52–63% silica, the lava is of intermediate composition.
    o These “andesitic” volcanoes generally only occur above subduction zones (e.g. Mount Merapi in Indonesia).
    * If the erupted magma contains 45% silica, the lava is called mafic (because it contains higher percentages of magnesium (Mg) and iron (Fe)) or basaltic. These lavas are usually much less viscous than rhyolitic lavas, depending on their eruption temperature; they also tend to be hotter than felsic lavas. Mafic lavas occur in a wide range of settings:
    o At mid-ocean ridges, where two oceanic plates are pulling apart, basaltic lava erupts as pillows to fill the gap;
    o Shield volcanoes (e.g. the Hawaiian Islands, including Mauna Loa and Kilauea), on both oceanic and continental crust;
    o As continental flood basalts.
    * Some erupted magmas contain <=45% silica and produce ultramafic lava. Ultramafic flows, also known as komatiites, are very rare; indeed, very few have been erupted at the Earth’s surface since the Proterozoic, when the planet’s heat flow was higher. They are (or were) the hottest lavas, and probably more fluid than common mafic lavas.

    Lava texture

    Two types of lava are named according to the surface texture: ʻAʻa (pronounced [ʔaʔa]) and pāhoehoe (pronounced IPA: [[Wikipedia:IPA|paːhoehoe]]), both words having Hawaiian origins. ʻAʻa is characterized by a rough, clinkery surface and is what most viscous and hot lava flows look like. However, even basaltic or mafic flows can be erupted as ʻaʻa flows, particularly if the eruption rate is high and the slope is steep. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Usually, only mafic flows will erupt as pāhoehoe, since they often erupt at higher temperatures or have the proper chemical make-up to allow them to flow at a higher fluidity.

    Volcanic activity

  4. Parts Of A Volcano

    Volcanic Cones and Craters
    Shapes of volcanoes include composite cones or stratovolcanoes, with steep concave sides such as Mt. St. Helens in the west United States; shield cones have gentle slopes and can be relatively large such as the Hawaiian Islands; and cinder cones as Paricutin in Mexico, with steep slopes made of cinder like materials. Explosive eruptions build up steep-sided cones, while the nonexplosive ones usually form broad, low lava cones. Cones range in height from a few feet to nearly 30,000 feet above their base. Usually the cone has as its apex a cavity, or crater, which contains the mouth of the vent. Such craters are typically less than 1 mile across, but larger craters, called calderas, ranging in diameter from 3 mi to–in a few instances–50 miles, are formed by particularly large eruptions.

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