rocks: materials of solid earth

• igneous
• sedimentary
• metamorphic

allows us to see many interactions amoung the components and processes of the earth system

• 1. starts with magma melting to become molten rock
• 2. magma cools and solidifies becoming igneous rock
• 3. weathering process disintegrates & decomposes into sediments
• 4. sediments move and comes to rest in places like oceans, flood plains, deseart basins, swamps and sand dunes
• 5. goes through process to convert into rock
• 6. rock becomes buried or involved in mountain building
• 7. if melts completely becomes magma and restarts cycle but doesn't necessarily go in this order

a body of molten rock found at depth, including any dissolved gases and crystals

formation and growth of a crystalline solid from a liquid or gas

formed as magma cools and crystalizes

molten rock that reaches the surface

formed when molten rock solidifies at the surface

formed when molten rock solidifies at depth

formed when slow cooling of the rock like below the surface

formed from instant cooling producing tiny shards of glass

size shape and distribution of the particles that collectively constitute a rock

formed rapidly at surface or as small masses within upper crust having vesicles (voids) left by gas bubbles

those that have voids or small cavities that are created by escaping gases

formed far below the surface having appearance of mass of inter grown crystal that are roughly equal in size large enough to identify the individual minerals

formed to start slowly then move to different environments having large crystals incased in matrix of small crystals

from volcanic eruptions when molten rock is rapidly cooled from unordered atoms that are frozen in place and from magmas having large amounts of silica; contain no crystals

iron and/or magnesium rick silicates relatively low in silica

most abundant minlar group feldspars as well as quartz, muscovite, mica; conain greater amounts of silica as well as potassium, sodium and calcuim in large amounts

entirely light colored having granitic composition of quartz and potassium felspar; major part of continental crust

has substantial dark silicate mineral as well as rich in calcium, no quartz; basaltic composition, darker and denser than grantic

compositional group containing 25%+ dark silicate minerals; other dominate is plagioclase feldspar

compositional group contains mostly olivine and pyroxene; entirely dark silicate minerals

illustates relationship between magma and minerals crystallizeing from it during formation of igneous rocks

• composition types - ultramafic, basaltic (mafic), andesitic (intermediate), granitic (felsic)
• minerals - olivine, pyroxene, amphibote, biotite mica, potassium feldspar, muscovite mica, quartz
• calcium rich before sodium rich

earlier formed minerals are denser than the liquid & sink toward the bottom

formation of one or more secondary magmas from a single parent magma

the natural response of Earth's materials to a new environment transforming rock

physcial breaking up of rock

altering what the rock is and changing it into a new substance

frost wedging, sheeting & biological activity

water works into cracks in rocks, freezes, expands & enlarges openings after many of these cycles it has browken the rock into pieces that tumble into talus slopes at the base of steep outcrop

large masses of intrusive igneous rock exposed by erosian, entire slabs break loose like onion layers; repeated creates separation & exfoliation domes

from activies of organisms creating fractures & wedging rock apart

alters internal structure of minerals by removing and/or adding elements altering into stable substances for surface environment; water most important part of this

in water forms carbonic acid, the acid reacts with franites quartz and potassium feldspar destroying the crystalline structure

detritus forming detrital sedimentary rocks

when back to solid called chemical sediment forming chemical sedimatry rocks

gravel sized particles if they are rounded

gravel sized particles if angular

when sand sized grains prevail made of very fine grained sediment

also fine grained difficult to differentiate from shale

even smaller clay sized sediment very fine

form from solid products; derived from material carried to lakes and seas

indirectly formed thru life processes of water dwelling organisms

most abundant of these composed of calcite, 90% biochemical

biochemical limestone; coarse rock made of cemented shells and shell fragments

soft, porous rock mostly of microscopic organisms

one example of inorganic limestone from chemical changes or high water temps increasing calcium carbonate

remaining deposits of salt deposition & seas gone

process that sediments transorm into solid sedimentary rocks

most common process of lithification; sediments accumulate over time the weight compress the deeper sediment reducing the pore space and creating rock

another imporant means of lithification; sediment is joined by water and cementing materials that go into the sediment; over the cement fills the open spaces joining the particles producing rock

single most characteristic feature of sedimentary rock

separate strata; flat surfaces along which rocks marking end of one episode & begining of another

ice remains of prehistoric life most important inclusions found in sedimentary rock

produced from pre-existing igneous, sedimentary or other metamorphic rocks; everyone has a parent rock

to change forms; leads to change in mineralogy, texture and sometimes chemical composition

• 1. contact (thermal) change caused by rise in temperature with the host rock
• 2. regional change during mountain building; large amount of rocks under direct pressure & high temps with large scale deformation

heat, pressure (stress) & chemically active fluids

any planer (nearly flat) arrangement of mineral grains or structural features within a rock layered or banded appearance

does not have uneven pressure the deformation is minimal & exhibits equidimensional crystals