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Geology

Ashley Atanasoff. Geology. How are rocks formed and distributed and what is their composition and texture like?. Igneous Rock Formation. formed when hot molten rock solidifies 2 types: intrusive and extrusive

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Geology

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  1. Ashley Atanasoff Geology How are rocks formed and distributed and what is their composition and texture like?

  2. Igneous Rock Formation • formed when hot molten rock solidifies • 2 types: intrusive and extrusive • intrusive- formed when magma is trapped deep inside the earth, cools slowly over thousand or millions of years until it solidifies • extrusive- formed when magma exits and cools outside the earth’s surface, it cools and solidifies almost instantly from the exposure to the cool temperature of the atmosphere

  3. Metamorphic Rock Formation • formed when rocks are heated and put under great pressure • not made from melted rock (rocks that melt will form igneous rock) • 2 types: contact and regional • contact- hot magma intrudes into cooler rock • regional- pressure and temperature change over distance

  4. Sedimentary Rock Formation • rivers carry pieces of broken rock as it flows • when a lake or sea is reached, the rock pieces settle to the bottom • the deposited pieces build up in layers (this is called sedimentation) • the weight of the sediments on top squish the sediments on the bottom (this is called compaction)

  5. Rock Distribution • the distribution of rocks is mostly due to plate tectonics • i.e. divergent plate boundaries, subduction zones, etc. • can be carried by wind, water, or glaciers

  6. Igneous Rock Composition • felsic- have a lot of feldspars and silica • intermediate- between felsic and mafic • mafic- have a lot of magnesium and iron with less silica • ultra mafic- even more magnesium and iron with even less silica

  7. Metamorphic Rock Composition • of foliated- composed of more than one mineral • of non-foliated- composed of only one mineral

  8. Sedimentary Rock Composition • clastic- made of rock/mineral pieces or fragments • chemical- made of crystals interlocked with each other • biological- made of an accumulation of organic material

  9. Igneous Rock Textures • phaneritic- made up entirely of crystals that are visible to the eye • aphanitic- made up entirely of small crystals that are not visible to the eye • porphyritic- both aphanitic and phaneritic • pegmatitic- made up entirely of large crystals • glassy- non-crystalline structure of the rock • vesicular- porous structure • breccia- broken, angular fragments of mixed compositions

  10. Metamorphic Rock Textures • slatey texture- fine-grained • phyllitic texture- contain mica-crystals • schistose texture- coarse grains • gneissic texture- coarsest grains

  11. Sedimentary Rock Textures • of clastic- grains are barely or not at all visible • of chemical- made up of crystals • of biologic- remains of organisms, shells, etc.

  12. Bibliography • http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/mincomp.html • http://faculty.chemeketa.edu/afrank1/rocks/metamorphic/mtexture.htm • http://facweb.bhc.edu/academics/science/harwoodr/geol101/Labs/Sediment/index.htm • http://www.bbc.co.uk/bitesize/ks3/science/environment_earth_universe/rock_cycle/revision/5/ • http://www.nationalatlas.gov/articles/geology/types/sedimentary.html • http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousCompositions.html • http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry14.html • http://geology.com/rocks/igneous-rocks.shtml • http://www.tulane.edu/~sanelson/eens212/metatexture.htm

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