Rocks

A rock is a group of minerals bound together in some way  Rocks are divided into three groups based on how the rocks formed  Igneous Rock,Sedimentart Rocks  Metamorphic Rocks

 Igneous rocks  Igneous rocks are formed by the cooling and hardening of molten rocks  Istrusive (Plutonic) form below the earths surface  Extrusive (Volcanic) from above the earths surface

 Physical properties  There are two physicla properties of igneous rocks ised in the identification od the roack name  Texture: referes to the size of the crystals in an igneous rock  **The larger the crystal size the deeper within the earth the rock formed  Color: Refers to the mineral composition of the rock  It is identified by using the general shade of the rock  If there are more light minerals than it is light of Felsic  If there are mroe dark minerals than it is dark or mafic <span style="font-family: Verdana,Geneva,sans-serif;"> If there is the same amount of dark minerals as light than it is medium <span style="font-family: Verdana,Geneva,sans-serif;"> Intrisive (Plutonic) Igneous Rocks <span style="font-family: Verdana,Geneva,sans-serif;"> Magma is molten rock underneath the earths surface <span style="font-family: Verdana,Geneva,sans-serif;"> Intrusive igneous rocks cool slowly deep within the earth and produces large crystals <span style="font-family: Verdana,Geneva,sans-serif;"> Intrusive igneous rocks will result in a very coarse,Pegmatite texture (EX. pegmatite) or coarse, (ex. Granite) <span style="font-family: Verdana,Geneva,sans-serif;"> Lava is molten rock that pours out onto the earths surface <span style="font-family: Verdana,Geneva,sans-serif;"> Extrusive rocks lack distinct mineral grains due to rapid cooling of lava at or near the earth's surface <span style="font-family: Verdana,Geneva,sans-serif;"> Extrusive igneous rocks will result in fine grain Aphanitic texture (EX Basalt) <span style="font-family: Verdana,Geneva,sans-serif;"> If the cooling is instantaneous a glassy texture may from (EX obsidian) <span style="font-family: Verdana,Geneva,sans-serif;"> If gas bubbles are rapped as the lava rapidly cools a vesicular texture may occur (pumice) <span style="font-family: Verdana,Geneva,sans-serif;"> Porphyritic Rocks <span style="font-family: Verdana,Geneva,sans-serif;"> Contains two stafes of cooling <span style="font-family: Verdana,Geneva,sans-serif;"> Cools first at great depth forming large crystals still surrounded by magma <span style="font-family: Verdana,Geneva,sans-serif;"> It is then rushed to the surface and the remaining liquid around it cools quickly forming Form grained crystals <span style="font-family: Verdana,Geneva,sans-serif;"> Granite-Quartz orthoclase feldsspar and at least one other mineral; light colored; coarse grained; makes up continetts;felsic <span style="font-family: Verdana,Geneva,sans-serif;"> Ryolite-fine grained granite felsic <span style="font-family: Verdana,Geneva,sans-serif;"> obsidian- volcanic glass; rapid cooling pyroclastic conchoidal fracture felsic to medium <span style="font-family: Verdana,Geneva,sans-serif;"> Pumice- sponge like because of escaping air bubbles during cooling; often floats; felsic <span style="font-family: Verdana,Geneva,sans-serif;"> Basalt- Fine grained; dark colored; makes up the ocena floor mafic <span style="font-family: Verdana,Geneva,sans-serif;"> Gabbro- coarse grained baslat mafic <span style="font-family: Verdana,Geneva,sans-serif;"> Diabase-Grain sixe inbetween baslat and grabbro; Mafic <span style="font-family: Verdana,Geneva,sans-serif;"> Basalt Glass-Mafic obsidian <span style="font-family: Verdana,Geneva,sans-serif;"> Scoria-Mafic Pumice

<span style="font-family: Verdana,Geneva,sans-serif;"> Sedimentary Rocks <span style="font-family: Verdana,Geneva,sans-serif;"> Rocks that form from an accumulation of sediments derived from preexisting rocks and organic materials <span style="font-family: Verdana,Geneva,sans-serif;"> sediments that harden into rocks <span style="font-family: Verdana,Geneva,sans-serif;"> Three kinds of sedimentary rocks <span style="font-family: Verdana,Geneva,sans-serif;"> Clastic Chemical (Crystalline <span style="font-family: Verdana,Geneva,sans-serif;"> Organic (bioclastic) <span style="font-family: Verdana,Geneva,sans-serif;"> Clastic Sedimentary Rocks <span style="font-family: Verdana,Geneva,sans-serif;"> Form from solid fragments (sediments) of other rocks examples: Shale sandstone conglomerate <span style="font-family: Verdana,Geneva,sans-serif;"> Sediments come from the weathering of existing rocks <span style="font-family: Verdana,Geneva,sans-serif;"> larger smalles <span style="font-family: Verdana,Geneva,sans-serif;"> Boulders pebbles sand silk and clay <span style="font-family: Verdana,Geneva,sans-serif;">Transportation of Sorting of Sediments <span style="font-family: Verdana,Geneva,sans-serif;">Fragments are moved mostly by running water <span style="font-family: Verdana,Geneva,sans-serif;">Winds waves and glaciers also move particles <span style="font-family: Verdana,Geneva,sans-serif;">The farther a particle travels the rounder it becomes <span style="font-family: Verdana,Geneva,sans-serif;">Rocks fragments separate through horizontal and vertical sorting <span style="font-family: Verdana,Geneva,sans-serif;">Lithifacation <span style="font-family: Verdana,Geneva,sans-serif;">is the compaction and cementation of rock fragments that form sedimentary rocks <span style="font-family: Verdana,Geneva,sans-serif;">In coarse sediments (gravel and sand) sediments do not stick together unless cemented. Dissolved minerals settle unto spaces between grains and bind them togetherThe larger the sediments in the rock the more permeable (ability to let water pass through) the rock <span style="font-family: Verdana,Geneva,sans-serif;">Conglomerate is a mixture of large rounded pebbles cemented together by smaller sediments <span style="font-family: Verdana,Geneva,sans-serif;">(breccia has angulas fragments <span style="font-family: Verdana,Geneva,sans-serif;">Sandstones are made largely of quartz grains (Permeable) <span style="font-family: Verdana,Geneva,sans-serif;">Shale forms the compaction of tiny flakes of clay (impermeable) <span style="font-family: Verdana,Geneva,sans-serif;">Chemical (crystalline) sedimentary rocks <span style="font-family: Verdana,Geneva,sans-serif;">form from the precipation of minerals of solution <span style="font-family: Verdana,Geneva,sans-serif;">the main cause for dissolved minerals to precipitate or drop out of the water is evaporation. (shallow sea environment) <span style="font-family: Verdana,Geneva,sans-serif;">This results in a crystalline mass of intergrown mineral crystals <span style="font-family: Verdana,Geneva,sans-serif;">Limestone composed primarily of calcite frizzles with HCL <span style="font-family: Verdana,Geneva,sans-serif;">Dolostone-Frozzes in HCL when powdered <span style="font-family: Verdana,Geneva,sans-serif;">Rock Salt- same properties of halite <span style="font-family: Verdana,Geneva,sans-serif;">Rock Gypsum- same properties of gypsum <span style="font-family: Verdana,Geneva,sans-serif;">Organic (bioclastic) sedimentary rocks <span style="font-family: Verdana,Geneva,sans-serif;">only sedimentary rocks can contain fossils <span style="font-family: Verdana,Geneva,sans-serif;">Form from the remains of living things or rocks containting fossils <span style="font-family: Verdana,Geneva,sans-serif;">Limestones-calcite and shells <span style="font-family: Verdana,Geneva,sans-serif;">Coal (sooty) burial of decayed plants; swamps <span style="font-family: Verdana,Geneva,sans-serif;">Fossiliferous shell- Shale containting fossiles <span style="font-family: Verdana,Geneva,sans-serif;">Stratification <span style="font-family: Verdana,Geneva,sans-serif;">Is the arrangement of different visible layers of rock. when the type of sediments found an area change new type of sedimentary rock forms ex: grand canyon <span style="font-family: Verdana,Geneva,sans-serif;">Fossils: are the remains impressions or any other evidence of plants and animals persevered in rock <span style="font-family: Verdana,Geneva,sans-serif;">Ripple Marks <span style="font-family: Verdana,Geneva,sans-serif;">Are formed by the action of winds streams waves and currents on sand and form on the surface of bedding planes <span style="font-family: Verdana,Geneva,sans-serif;">Mud cracks <span style="font-family: Verdana,Geneva,sans-serif;">develop when deposits of wet clay dry up and contract <span style="font-family: Verdana,Geneva,sans-serif;">Geodes <span style="font-family: Verdana,Geneva,sans-serif;">are hallow spheres in which groundwater has deposited minerals <span style="font-family: Verdana,Geneva,sans-serif;">Metamorphic rocks <span style="font-family: Verdana,Geneva,sans-serif;">rocks which are formed from existing rock (sedimentary igneous metamorphic) by the action of heat, pressure and chemicals <span style="font-family: Verdana,Geneva,sans-serif;">Parent rock- the rock which becomes metamorphosed <span style="font-family: Verdana,Geneva,sans-serif;">Metamorphism: the process of forming metamorphic rocks within the lithosphere making the rocks more dense and less possible <span style="font-family: Verdana,Geneva,sans-serif;">Properties of MEtamprphic Rocks <span style="font-family: Verdana,Geneva,sans-serif;">caused by intense heat and pressure on the rocks more dense and less porus then the parent rock form whic it formed <span style="font-family: Verdana,Geneva,sans-serif;">Recyrstallization is the process of increasing the size of the mineral crystals and or changing the mineral composition without melting <span style="font-family: Verdana,Geneva,sans-serif;">Foliation-parallel layers of minerals caused by pressure on the rocks <span style="font-family: Verdana,Geneva,sans-serif;">Regional Metamorphism: <span style="font-family: Verdana,Geneva,sans-serif;">When large area of rocks are under intence heat and pressure causing them to change form (results in foliation) <span style="font-family: Verdana,Geneva,sans-serif;">Example-the building of mountain ranges <span style="font-family: Verdana,Geneva,sans-serif;">The foliation increases as hear and pressure are added <span style="font-family: Verdana,Geneva,sans-serif;">(low-grade--high-grade) <span style="font-family: Verdana,Geneva,sans-serif;">Low grade slate phyllite schist <span style="font-family: Verdana,Geneva,sans-serif;">High Grade gneiss <span style="font-family: Verdana,Geneva,sans-serif;">Contact Metamorphism <span style="font-family: Verdana,Geneva,sans-serif;">occurs when hot magma intrudes into overlaying rocks and bakes the rocks in contact with it. <span style="font-family: Verdana,Geneva,sans-serif;">Less rock is affected then in regional <span style="font-family: Verdana,Geneva,sans-serif;">Change in the rock is less drastic no foliation <span style="font-family: Verdana,Geneva,sans-serif;">Non foliated rocks <span style="font-family: Verdana,Geneva,sans-serif;">Quartzite <span style="font-family: Verdana,Geneva,sans-serif;">Marble <span style="font-family: Verdana,Geneva,sans-serif;">Hornfels