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

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

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

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)

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

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

of foliated- composed of more than one mineral of non-foliated- composed of only one mineral

clastic- made of rock/mineral pieces or fragments chemical- made of crystals interlocked with each other biological- made of an accumulation of organic material

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

slatey texture- fine-grained phyllitic texture- contain mica-crystals schistose texture- coarse grains gneissic texture- coarsest grains

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

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