INTRO TO THE EARTH
INTRO TO THE EARTH GEOL 101
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This 11 page Class Notes was uploaded by Brandon Dickinson on Monday October 26, 2015. The Class Notes belongs to GEOL 101 at University of South Carolina - Columbia taught by Ad Cohen in Fall. Since its upload, it has received 13 views. For similar materials see /class/229615/geol-101-university-of-south-carolina-columbia in Geology at University of South Carolina - Columbia.
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Date Created: 10/26/15
3 E0 101 August 18m lDayl Notes and interior of Earth Battle otAntietam Lots of people died because the battle was fought over Limestone Limestone creates flat low lying areas I II I a ughtover igneous intrusionslhigh points Geology Geo Earth Logisstudy study ofthe earth 1 Physical Geology study of Earth s materials and processes 2 Historical Geology History and evolution of Earth Structure ofthe Earth 1 Core 2 LowerMantle 3 UpperMantle 4 Crust Other portions of Earth 1 Asthenosphere most of upper mantle except most near surface portion Capable of ow and moves by heat through convection currents Below litoshphere Lithosphere Crust and Upper Part of Upper Mantle Contains Continental Crust and OceanicCrust Rigid Solid v Plate Tectonics capable of movement by plates The Rock Cycle 3993 f new volcanic mpllun mum All rocks become other rocks Igneous rocks come from molten rock and then weather and become sedimentary rocks Sedimentary Rocks become metamorphic which melt with magma and harden again to form igneous rocks August 23rd Notes Matter and Minerals Minerals Definition of Mineral A naturally occurring inorganic crystalline solid with a narrowly defined chemical composition and characteristic physical properties you can not make a mineral because it is naturally occurring It has to be a solidwater isn t a mineral Definition of Rock An aggregate of minerals but it can be one or more minerals Can be an aggregate of maceralsorganic equivalent of minerals and minerals Building Blocks of Minerals a Matter anything that has mass and occupies spaceliquid gas solid All matter is made up of elements each of which is composed of an atom ElementsAtoms Smallest unit of matterlook up a picture of a carbon atom Nucleus in the center and contains protons and neutrons Electrons orbit the nucleus The name ofthe atom is determined by number of protons and neutrons in the nucleusCarbon 12 atom has six protons and six neutrons in the nucleus Compounds When two or more elements are bonded together Most minerals are compounds Chemical Formulas How to show which way the elements are in the compound Ex Calcite would be written CaC03 b v n v 9 v IV Characteristics of Minerals CrystalsCrystallline Solids Internally it is crystalline but is very hard to tell from the outside Internally there is a various connection between elements Cleavage look up Chemical Compositions Different chemical compositions will make a different mineral name V Physical Properties of Minerals a Color some minerals will have one color and some minerals will have multiple colors Take a mineral and streak it against a porcelain plate and see what color it is Called the streak test or scratch test The other way is to just hold it in your hand and see what color it isquotn Hand or Streak testquot Luster what does the mineral look like in the naked eye in terms of light reflection and how it is reflecting The way light interacts offthe mineral Some have a metallic luster Some have a greasy or waxy luster Some have a brilliant luster Some have an earthy luster Glassy or vitreous lusterquartz has this kind of luster c Crystal form Whole bunch of different crystal forms Cubic Garnet Diamond d Cleavage take the rock and hit it with a hammer and see how it breaks Micah mineral has cleavage in one direction because it is like a flat sheet Graphite also has perfect cleavage in one direction You can also look at the angles ofthe cleavage Cleaveage in two directions at right angles includes potassium Cleavage in three directions at right angles includes Halite Diamond has cleavage in four directions Calcite has cleavage in three directions not at right angles though Sphalerite has cleavage in six directions Three qualities of cleavage Perfect cleavage good cleavage poor cleavage e Hardness Moh s Scale of Hardness It is based on a series of minerals that have different hardness Diamond is the hardest mineral Talc is the softest mineral The following are still physical properties of minerals fSpecific Gravity Ratio of the weight of the mineral to the weight of an equal volume of water G Other Properties quotsoapy greasy or waxyquot tac quotwrites on paperquot graphite salty tastequot halite magneticquot magnetite doube refraction and reacts with HCI calcite Calcite will bubble if you add hydrochloric acid and it produces carbon dioxide Calcite produces double refraction Outcrop An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth View V Classification of Minerals 0 8 major Groups based on crystal structure and chemical compostion 1 Native Elements gold silver diamond graphite copper etcsimpest element They have one element and are not compounds 2 Sulfides xsome other element sulfur has 2 to 3 elements Halides x fluorine chlorine bromine or iodine 2 to 3 elements Salt is a Halide 9 P 9quot 59quot 9 39 Oxides x oxygen 2t 0 3 elementsCorundum is an oxide second on the moh s hardness scale Ruby and Saphire are oxides that come from the Corundum element Sulfates x sulfuroxygen 3 to 4 elements or moreCacium Sulfate Gypsum is a sulfate Ca 504 2 H20 Produced and dried up like rock salt Carbonates x carbonoxygen 3 to 4 elements or moreLimestone Phosphates xphosphorousoxygen 3 to 4 elements or moreFertilizers have phosphate in them as well as things like detergents Silicates x silicone oxygenquartz feldspar clays micah 3 to 4 or more elements Silicate Tetradedron structural basis of all silicate structures Silicate Structures can be a single tetrahedronOlivine single chains double chains sheets or 3D networks Things like quartz has poor cleavage because they have 3D tetrahedron networks and they are all bound together tightly X stands for some other element Silicon and OXLqen make up the most minerals in the Earth s Continental Crust Oxygen makes uE the most with 45 and Silicon has around 27 Diamond is a native element that starts out as coal Canada is becoming one of the newest spots to get diamonds Feldspar is the most common element in the Earth39s crust Clay can mean size or actual mineral formula 830 Lecture Weathering Introduction A Definitions WeatheringDecompostion and disintegration The physical breakdown and or chemicalphysical alteration of rocks and minerals at the earth s surface Physical alteration is the same thing as decomposition Erosion The removal of weathered material by water wind etc Also called transportation Weathering and Erosion often get confused and are not the same thing Don t mix the two up A 03 0 Importance of Weathering 3 things 1Weathering forms sedimentary rocks All rocks on the East near the coast are in layers and lay flat and are all sedimentary rocks 2t also forms soils If it weren t for soils there would be no living things 3 It is the origin of certain mineral resources Aluminum is the product of weathering Weathering is not uniform It is differential That means it doesn t weather everything the same Weathering effects natural and manmade structures Effected brownstone in the Baltimore and Philadelphia region D Two types Mechanical and Chemical Mechanical Weathering Mechanical Weathering The breakdown of rocks into smaller pieces by physical forces 1 Types of Physical Processes 1 Frost Action Repeated freezing and thawing of water in rocks Frost Wedging water seeps into cracks and crevices of rocks then freezes and thaws Upon freezing Water expands by 9 and starts to crack the rocks quotTalusquotlook up Talus will be on exam at the base of a mountain has frost action and frost wedging Can happen in desert areas Frost wedging happens in places where water freezes and thaws every night Talus is like a slope formed by rock fragments formed at the bottom of a mountain or clff Frost Heaving Water goes underneath some structure like concrete or underneath the soil then freezes and whole mass is lifted upexpands upward because water expands so quickly9 2 Pressure Release Processes that results from the release of energy by rocks that formed at great depth that are later exposed at the surface Example is igneous rocks Sheet joints Exfoliation Material that is coming off rocks or exfolitating Stone Mountain is a good example of a sheet joint and an exfoliation domeexam question 3 Thermal Expansion and Contraction Thermal expansion causes the hot portion of the rock to expand but the inner part can be cool so the outside will break off In the desert rock can be heated very much on the outside and this thermal expansion and contraction happens in the desert 4 Activities of organisms Plant Roots Plants can grow in rocks if there is a little soil there and break up the rock Burrowing Animals can dig down into rock and form little burrows breaking up the rock Chemical Weathering Process where by rock materials are decomposed by chemical alterations and chemical agents 1 Three things may result 0 Formation of new minerals Nearly all Clay minerals come from the chemical weathering of other rocks 0 Complete decomposition of certain minerals o Liberation of more resistant minerals from the parent rock 2 Effect of organisms Some organisms can start eating the rock and create a little chemical environment Mainly microorganisms Can change the PH of the rock B Dissolution dissolving One of the impacts of this chemical weathering is the formation of caves Caves are hollowed out by the dissolving Halites and limestone dissolve under water forming caverns Stalagtites and stalagmites are formed through this process 0 acid rain natural acidity All rain has some acid in it which is usually Carbonic Acid Sulfuric Acid and Nitric Acid can also get in the air and get in rain sulfuric acid and nitric acid are man made that are omitted from chemical plants and such The more acid you get in rain the more it will decompose things like Limestone and Marble Natural Acidity Erupting volcanoes can produce a lot of sulfur dioxide Bacteria can create acid conditions Decomposing leaves can also produce acid Sphagnum moss can also create acid and is acidic Will be a test question which of the following C Oxidation combining with oxygen Hematite is formed by this Usually occurs in dark rocks Causes materials to rust Most common in minerals that have Iron in them Ferromagnesian minerals are very dark when they come into contact with oxygen and then weather they produce red or orange colors When you have red color in the rock or soil it had iron in it On Exam Hematite is a reddish color and Limonite has a yellowish color Extra Credit where does the origin ofthe name Limonite come from D Hydrolysis Chemical reaction between the ions in water with the ion in the mineral that is being weathered Potassium Feldspar water forms clay minerals Also produces Silicamakes up quartz which is the source that cements rocks Silica is basically a cement that silicify rocks Silica can cement your water pipes Hydrolysis of feldspar yields clay minerals E Factors effecting rate of chemical weathering 1 Particle Size The smaller the pieces the more surface area that can be weathered The smaller the size the easier it is to weather Physical weathering breaks things into smaller pieces 2 Climate Warm and wet conditions there can be more chemical weathering Not a lot of weathering in desert areas but in tropical areas there can be many feet of weathering 3 Composition of rock 4 Slo Steep slope weathers quickly The reason is that there is more erosion 5 Deforestation Accelerates weathering and erosion F Spheroidal weathering Process by which the edges and corners are removed by chemical weathering that produces spheres Especially in Granite Soils A Definition Unconsolidated weathered rocks and mineral fragments with air water and organic matter B Importance of soil There would be no life on Earth without soil 0 There are layers of soil and it is less and less weathered as you get lower into the soil C Horizons There are four horizons layers in soil 1 OUpper thin layer of organic matter 2 A Zone of leaching Leaches minerals out of the soil 3 B Zone of accumulation Aluminum Oxide accumulates in this zone on exam 4 C Partially altered to unaltered parent material Some soil diagrams include a E horizon that has light colored mineral particles included in the zone of eluviation and leaching D Factors controlling soil formation 5 factors 0 Climate n tropical areas there is usually a thick soil No soil in the desert because it is warm but no precipitation The area we live in temperate environment we have an intermediate soil because it is warm with some precipitation Places like the Artic where it isn t warm and little rain has little soil Tropical soils are called Lateriteson exam Laterites have a huge zone of leaching and accumulation which has Boxites Parent rock the rock from which the soil is formed Organic activity Burrowing of roots into the soil Centipides and millipedes and worms will eat it up Breakdown of organic activity Organic acids can break down soil 0 Relief and Slope Two different things Steeper slope decreases the amount of soil Slope is the angle Relief is the difference between the highest and lowest points 0 Time amount of time rock has been exposed or soil F Soil Erosion two types water flowing over the surface 1 Sheet Erosion When the water falls down or rain comes down the water just slides off in flat sheets 2 Rill Erosion Water holds together and moves like a river Moves like Little tiny channels Rills are tiny rivers Larger rills are reffered to gullies Sedimentary Rocks Definition Products of chemical or mechanical weathering of other rocks or Accumulations of plant or animal derived substances A Occurrence and Distribution Usually sedimentary rocks are in layers and are layered Only 5 of the Earths crust contains sedimentary rocks About 90 of crust contains are igneous rocks 75 of Outcrops are sedimentary rocks on the continents sedimentary rocks come from fossils Only rock that can come from plant or animal fossils B Importance of sedimentary rocks three things 0 Past environments and life Sedimentary rocks can come from fossils Only rock that can come from plant or animal fossils A sedimentary environmentdepositional environment Sedimentary rocks could be in a shoreline environment a nearshore high energy environment off shore low energy environments 0 Past Processes 0 Economic materials Many economic materials come from sedimentary rocks Coal is a type of sedimentary rock Oil comes from sedimentary rocksoi is derived from organic material Oil drillers know where to drill because they look for the Source Rock Another economic material that comes from sedimentary rocks is construction materials Iron and aluminum come from SM as well On Exam Types of Sedimentary Rocks Detrital and Chemical A DetritalClastic Sedimentary rocks An accumulation of solid particles or fragments weathered mechanically physically from other rocks 0 1 Most common minerals composing these kinds of rocks Clay minerals and quartz The important thing about clay is that it has two meanings Clay can be clay minerals or Clay Size particle size Micah and Feldspar are also detrital sedimentary rocks but are very easily weathered so if in a rock then it hasn t traveled very far 0 look up compaction and cementation this is how quotsedimentquot becomes quotrock 0 2 Particle Size Classificationfrom clay to boulder if the size is greater than 2mm it is probably Gravel 116 2mm it is sand 1256 116 it is silt ltless than 1256 it is clay Mixtures of silt and clay are generally referred to as mud On Exam 0 3 Generally larger sizes mean swifter currents for example if you find something like clay it is probably in a lake which is a very slow moving body of water You can find gravel in fast moving rivers Find sand in a slower moving river or stream Maybe find silt in a creek 0 Clay compacted turns into Shale random fact Silt commpactdcemented turns into siltstone Sand turns into sandstone after compactcemented 0 Types of detrital sedimentary rocks 0 1 Shalesmudstones claysize and siltsize particles 50 of all sedimentary rocks are Shales They are tightly packed together More crumbly and pretty easily weathered and eroded Readily can be split into layers Pottery is made out of shale Bricks tiles china and cement as well Oil shales are shales with very fine organic material Places that don t have a lot ofshales don t have a lot of buildings and stuff cause no cement o Sandtones sandsize particles 20 of all sedimentary rocks on the continent 1 sorting The degree to which the particles that are making up the rock are the same size 2 shape The more it travels the more the corners and edges are cut off and it becomes well rounded 3 rounding Knocking off the corners and making it round like a smooth pebble 4 mineral composition color will tell you what type of mineral it is On Exam 0 Conglomerates v Breccias Conglomerates are a bunch of rounded pebbles that are stuck together to form one rock Breccias are angular particles that are made into a rock On Exam Breccia Chemical Sedimentary Rocks 1 Definition Rocks derived from chemicals dissolved in water and precipitated or of biochemical origin Salt Halite is an example of something that is precipitated 2 Types a Limestones CaCOS Makes up 10 of all sedimentary rocks 90 of Limestone is biochemically derived meaning coming from plants or animals 1 general biological v nonbiological sources 90 of Limestone is biochemically derived meaning coming from plants or animals 2 Coquina Bunch ofshell fragments Usually would from on a beach with a lot of shells It is a rock of a bunch shell fragments cemented together with calcium carbonate 3 Chalk Afine grained limestone If you go to a place where chalk is occurring naturally it is being made up of marine organisms Chalk can also be made up of Gypsum 4 algal stromatolites Formed entirely from algae It is layered and Looks like leaves of cabbage On exam Each ofthe layers represents what used to be a layer of algae 5 Travertine Cave limestone 6 Oolitic Limestone Oolite means eggs Egg like limestone The rock has little tiny looking eggs on it How do you get those little tiny eggs on the rock Only forms in places like Bahamas with very shallow water with gentle waves The rocks are made up of little fragments that are coated with calcium carbonate The shell fragments are in the center of the rock that are coated B Dolomite Ca Magnesium carbonates Dolomite is a rock and a mineral Dolostone is the chemical sedimentary rock we are talking about C Cherts SiOZ Micro crystalline silica rock made of marine organisms A hard dense rock Types of Cherts Agate made up of several different colored bands Jasper is red in color Used for beads and jewelry Flint more of a brownish or grayish color Jasper and Flint could easily be made into arrowheads On Exam D Evaporites Halite salt Gypsum The order of the precipitation ofthe evaporite Least soluble precipitates firstGypsum precipiates before salt More soluble precipitates latersalt Making Sediments into Rocks Lithification o Compaction The sediment has to be covered up or compress it o Cementation Three types of cement Calcite Silica Iron Oxide on exam VI Sedimentary Environments and Sedimentary Structures A Sedimentary Environments 1 Terrestrial On land 2 Marine Sea B Sedimentary Structures 1 Mud Cracks sometimes have rain drop structures on them 2 Ripple Marks Formed from wave action or wind Basically moving the sand into little rows Two types Current and Oscillation Oscillation ripple mark the wave motion goes back and forth near the shore and the ripples are pointed at the top Current ripple marks go with the current water or wind Rounded at the top 3 Strata beds Occur in layers The most distinctive thing about sedimentary rocks Most sedimentary rocks occur in layers stratas On exam 4 Graded Bedding The bottom of the layer is called a bedding plain Coarser at the bottom and much finer at the top 0n exam 5 Cross bedding Thin layers of sediment between the bedding that are formed cross ways to the main horizon Formed by sand dunes turbidity current landslide of water that is a little denser because of all kinds of sediment mixed into it As turbidity current slows largest particles settle at the bottom Extra Credit Due on class after the exam Next Thursday Worth three points From my last two lectures Weathering and Sedimentary Rocks tell me as much as you can about the composition of these rocks and rock formations and how they formed In reconstructing the history always describe the older things first and continue to the present This can be in the form of a list of numbered events or processes Start with the bottom ofthe rock first which is the older part Turn in your labeled sketch along with your written answers Your list should refer to numbers on your sketch item 1 in your list should refer to 1 on your sketch 2 to 2 sketch etc You have to label the sketch
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