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

Geology

Ashley Atanasoff

formed when hot molten rock solidifies2 types: intrusive and extrusiveintrusive- 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

Igneous 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 regionalcontact- hot magma intrudes into cooler rockregional- pressure and temperature change

over distance

Metamorphic Rock Formation

rivers carry pieces of broken rock as it flowswhen a lake or sea is reached, the rock pieces

settle to the bottomthe 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)

Sedimentary Rock Formation

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

Rock Distribution

felsic- have a lot of feldspars and silicaintermediate- between felsic and maficmafic- have a lot of magnesium and iron with

less silicaultra mafic- even more magnesium and iron

with even less silica

Igneous Rock Composition

of foliated- composed of more than one mineral

of non-foliated- composed of only one mineral

Metamorphic 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

Sedimentary Rock Composition

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 phaneriticpegmatitic- made up entirely of large

crystals glassy- non-crystalline structure of the rockvesicular- porous structurebreccia- broken, angular fragments of mixed

compositions

Igneous Rock Textures

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

Metamorphic Rock Textures

of clastic- grains are barely or not at all visible

of chemical- made up of crystalsof biologic- remains of organisms, shells,

etc.

Sedimentary Rock Textures

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

Bibliography