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Date Created: 11/01/15
GLG111 Final 12102009 30700 PM CH l7 The hydrologic system and groundwater Reservoir 0 A place in which water is stored o Earth s main natural reservoirs 39 Oceans 39 Glacierspolar ice 39 Ground water 39 Lakesrivers 39 The atmosphere I The biosphere 0 Distribution of water among reservoirs 0 Salt water 9596 39 Mostly found in oceans and seas 0 Fresh water 404 39 Mostly found in D glacierspolar ice 297 D ground water l05 The hydrologic cycle 0 The cyclical movement of water from the ocean to the atmosphere by evaporation to the surface through ran to the streams through runoff and ground water and back to the ocean o Runoff o The sum of all rain water that flows over the surface including the fraction that may temporarily infiltrate near surface formations and then flow back to the surface 0 Infiltration o The process by which water enters rock or soil through joints or small pore spaces between particles 39 Water that does not infiltrate the ground runs off the surface gradually collecting into streams Saturated zone phreatic zone 0 The level in the groundwater table in which the pores of the soil or rock are completely filled with water Unsaturated zone vadose zone 0 The level in the groundwater table in which the pores of the soil or rock are not completely filled with water 0 the saturated and unsaturated zones can be either unconsolidated material or bedrock Water table 0 the boundary between the saturated and unsaturated zones Porosity vs Permeability 0 Pores can occur as three types 0 Intergranular porosity the space between grains 39 Depends on the size and shape of the grains that make up the soils and how they are packed together The more loosely packed the grains the greater the pore space between them The smaller the particles and the more they vary in shape the more tightly they fit together 0 Fracture porosity the space in fractures o VHggy porosity the space created by dissolution Permeability o The capacity of a solid to allow fluids to pass through it o Depends on sizes of pores how well they are connected and how tortuous a path the water must travel to pass through the material I The smaller the pore spaces and the more tortuous the path the slower the water travels 0 generally permeability increases as porosity increases 0 a good groundwater reservoir is a body of rock sediment or soil with 0 high porosity so that it can hold large amounts of water 0 high permeability so that the water can be pumped from it easily 0 Rocks and sediments that make good aquifers o Gravel 39 Very high porosity pore space that may hold fluid and permeability ability to allow fluids to pass through 0 Course to medium grained sand 39 high porosity and permeability 0 fine grained sand and silt 39 moderate porosity moderate to low permeability o unfractured shale 39 very low porosity and permeability Confined vs Unconfined Aquifers 0 Aquifer a bed that stores and transmits groundwater in sufficient quantity to supply wells Groundwater may flow in confined or unconfined aquifers Confined aquifers 0 When aguiludes lie bother over and under an aquifer o Aguilude a relatively impermeable bed that bounds an aquifer above or below and acts as a barrier to the flow of groundwater 39 The impermeable beds above a confined aquifer prevent rainwater from infiltrating directly into the aquifer D A confined aquifer is recharged by precipitation over the recharge recharge the infiltration of water into any subsurface formation area Rainwater can enter here bc there is no aguilude 0 Water moving through a confined aquifer Artesian flow 0 This water is under pressure 0 Unconfined aquifers o The water travels through the beds of more or less uniform permeability that extend to the surface in both discharge and recharge areas 0 The level of the reservoir in an unconfined aquifer is the same as the height of the water table 0 When recharge and discharge are balanced the reservoir of groundwater and the water table remain constant 0 For recharge to balance discharge rainfall must be freguent enough to compensate for the runoff from rivers and the outflow from springs and wells 0 not always egual bc rainfall varies 0 water table drops during dry seasons and rises during wet periods 0 a decrease in recharge ie prolonged drought leads to a longer term imbalance and a lowering of the water table 0 an increase in discharge ie well pumping can produce the same imbalance 39 water is pumped out faster than recharge can replenish it then the water level in the aquifer is lowered in a cone shaped area around the well called a cone of depression 0 The balance between recharge and discharge in the freshwater aguifer maintains the freshwater seawater boundary 0 as long as recharge by rainwater is at least equal to discharge by pumping the well will provide fresh water 0 if water is withdrawn faster than it is recharged a cone of depression develops at the top of the aquifer o Gaining amp loosing streams o Karst topography 39 An irregular hilly terrain characterized by sinkholes caverns and lack of surface streams 39 Scarce streams often end in sinkholes detouring underground and sometimes reappearing miles away will disappear and go underground then reappear from underground miles from where it disappeared D Found in regions with 3 characteristics 0 A high rainfall climate with abundant vegetation providing carbon rich waters 0 Extensively jointed limestone formations 0 Appreciable hydraulic gradients 0 The speed at which water moves in the ground strongly affects the balance between discharge and recharge 0 Most groundwaters move slowly o Henri Darcy 39 for a given aquifer and distance of travel the rate at which water flows from one point to another is directly proportional to the drop in elevation of the eater table between the two points As the difference in elevation increases the rate of flow increases 39 basically ground water flows faster down a steeper slope than a more gradual one 0 Ground water may travel as much as l5 cm per day in very permeable gravel beds near the surface Main use of groundwaterGroundwater mining 0 Groundwater is used for all water needs 0 lrrigation industrial public supply rural 0 Domestic water use 0 Minimum reguirements 39 Drinking 39 Sanitation 39 Bathing 0 Groundwater mining O US O 0 when you mine a lot of ground water surface drops water resources Under stress Ogalla aquifier 39 Water table dropped significantly 30 50 years left Chapter l8 12102009 30700 PM Streams Drainage Patterns Dendritic drainage 0 Characterized by branches similar to a tree 0 Most rivers follow this irregular branching pattern 0 Typical in terrains where bedrock is uniform Rectangular o Developed on a strongly jointed rocky terrain o Tends to follow the joint pattern Trellis drainage 0 Develops in valley and ridge terrain where rocks of varying resistance to erosion are folded into anticlines and synclines Radial drainage 0 Patterns develop on a single large peak such as a large dormant volcano Antecedent stream 0 A stream that existed before the present topography was created and so maintained its original course despite changes in the structure of the underlying rocks and in topography Superposed stream 0 A stream that erodes a gorge in resistant formations because its course was established at a higher level on uniform rocks before down cutting began A superposed stream tends to continue the pattern it developed earlier rather than adjusting to its new conditions I In this case a dendriditic pattern is forced onto a surface that would otherwise be rectangular Drainage basin 0 An area of land bounded by divides that funnels all its water into the network of streams draining the area Channel Types o Meanders o Curves and bends that channels follow 0 Usually found in streams flowing on low slopes in plains or lowlands where channels typically cut through unconsolidated sediments fine sand silt or mud or easily eroded bedrock Less pronounced but still common where channels flow 0 on higher slopes and harder bedrock Found not only in streams can be found in lava O flows and the gulf stream in the north atlantic ocean O Migrate over many years eroding the outside banks of bends 39 as the outside banks are eroded curved sandbars called point bars are deposited along the inside of the banks where the current is slower O Meanders migrate 39 Sometimes unevenly which leads to the bends being closer and closer together D Eventually the river bypasses the next loop the river then takes a shorter path and in its abandoned path leaves behind a crescent shaped water filled loop called an oxbow lake 0 Braided streams o Stream whose channel divides into an interlacing network of channels which then rejoin resembling braids of hair 0 Found in many settings I From broad lowland valleys to wide sediment filled valleys adjacent to mountain ranges 39 Tend to form in rivers with large variations in volume of flow combined with high sediment load and easily erodible banks Fluvial Landforms o Floodplains o A flat area about level with the top of the channel 0 Lies on either side of the channel o It is the part of the valley that is flooded when the river spills over its banks carrying with it silt and sand from the main channels 0 Levees 0 natural levees ridges of coarse material that confine the stream within its banks between floods even when the water levels are high 0 successive floods build up natural levees o Deltas o a depositional platform built of sediments deposited in an ocean or lake at the mouth of a stream 0 as a river approaches a delta where the slope profile is almost level with the sea it reverses its upstream branching drainage pattern Instead of collecting more water from tributaries it discharges water into distributaries smaller streams that receive water and sediment from the main channel branch off downstream and thus distribute the water and sediment into many channels 0 Alluvial Fans 0 A cone or fan shaped accumulation of sediment deposited where a stream widens abruptly as it leaves a mountain front for an open valley 0 Results from the sudden decrease in velocity that occurs as the channel widens abruptly o Oxbow Lakes 0 A crescent shaped water filled loop created in the former path of a stream when it abandons a meander and takes a new course Stream flow Laminar vs Turbulent o Laminar Flow 0 The simplest kind of movement Straight or gently curved streamlines run parallel to one another without mixing or crossing between layers Kind of like the slow movement of syrup with the movement of unmixed butter next to it over pancakes o Turbulent Flow 0 O 0 Has a more complex pattern of movement Streamlines mix cross and form swirls and eddies Fast moving river waters typically show turbulent flow 0 Whether a flow is laminar or turbulent depends on O O O Erosion lts velocity rate of movement lts geometry primarily its depth lts viscosity flow measure of a fluid s resistance to l The more vicious the thicker the more it resists to flow a fluid is D the higher the viscosity the greater the tendency for laminar flow 0 Abrasion 0 One of the major ways a river breaks apart and erodes rock The erosive action that occurs when suspended and saltating sediment particles move along the bottom and sides of a stream channel The sand and pebbles the river carries create a sandblasting action that wears away even the hardest rock 0 Chemical weathering O The weathering that occurs when the minerals in a rock are chemically altered or dissolved Alters a rock s minerals and weakens it along joints and cracks helps destroy rocks in streambeds just as it does on the land surface 0 Physical weathering o Weathering in which solid rock is fragmented by mechanical processes that do not change its chemical composition 0 Can be violent o o Undercutting o Tremendous impact of huge volumes of plunging water and tumbling boulders quickly erodes rock beds below waterfalls o Waterfalls also erode the underlying rock of the cliff that forms the falls 0 As erosion undercuts these cliffs the upper beds collapse and the falls recede upstream Sediment Transport Suspended vs Bed load 0 Suspended Load 0 Includes all the material temporarily or permanently suspended in the flow 0 Bed load 0 The material the stream carries along the bed by sliding and rolling Sediment Erosion and Transport 0 Laminar flows can life and carry only the smallest lightest clay sized particles 0 Turbulent flows depending on speed can move particles ranging from clay sized to pebbles and cobbles o The faster the current the larger the particles carried as suspended and bed load I A flows ability to carry material of any given size is its competence 39 The larger the volume of flow the more suspended load and bed load can carry D Total sediment load carried by a flow is its capacity 0 The velocity and the volume of a flow affect both the competence and capacity of a stream 0 small floods are more frequent every 2 3 years 0 large floods are less frequent every lo 20 30 years 0 rivers flood regularly 0 some in infrequent intervals others every year 0 impossible to predict how high a flood will be only probabilities 0 the average time interval between the occurrence of 2 geological events of a given magnitude is called reoccurrence interval 0 o Graded stream 0 A stream in which the slope velocity and discharge combine to transport its sediment load with neither sedimentation or erosion o If the conditions that produce a particular graded stream profile change the stream s profile will change to reach a new equilibrium 0 Equilibrium o a stream is in dynamic equilibrium between erosion of the streambed and sedimentation in the channel and floodplain over its entire length 0 controlled by five factors 39 topography including slope 39 climate 39 stream flow I the resistance of rock to weathering and erosion 39 sediment load 12102009 30700 PM Chapter 21 Glaciers Glaciers 0 large masses of ice on land that show evidence of being in motion or of once having moved under the force of gravity 0 valley glaciers alpine glaciers 39 a river of ice that forms in the cold heights of mountain ranges where snow accumulates usually in preexisting valleys and flows down the bedrock valleys 39 usually occupies the complete width of the valley 0 continental glaciers ice sheet I an extremely slow moving thick sheet of ice that covers a large part of a continent largest ones today over Greenland and Antarctica 39 upper surface of the ice sheet resembles an extremely wide convex lens How do glaciers move amp how quickly Movement by Plastic Flow 0 Movement occurs as deformation within the glacier 0 The total of all the small movements of the ice crystals that make up a glacier resulting in a large movement of the whole mass of ice 0 Most important in very cold regions were the ice throughout the glacier including its base is well below the freezing point 0 The basal ice is frozen to the ground and most of the movement of these cold dry glaciers takes place above the base by plastic deformation 0 Movements near the frozen base detach and transport pieces of bedrock and soil Movement by Basal Slip 0 Glacier slides down slope as a single unit along its base like a block of ice sliding down a ramp 0 The sliding of a glacier along the boundary between the ice and ground 0 The melting point of ice decreases as pressure increases so the ice at the base of a glacier where the weight of the overlying ice is greatest melts at a lower temperature 0 The melted ice lubricates the base of the glacier causing it to slip down slope How fast do glaciers move 0 3 300 m per year 0 what controls the rate of movement 0 Creep deformation of ice 39 lndividual ice crystals slip over microscopic distances over short periods of time plastic 0 Glacier crevasse a large vertical crack in the surface of a glacier caused by the movement of brittle surface ice as it dragged along by the plastic flow of the ice below Glacial landforms O 0 Flow in valley glaciers 0 Observed that the fastest motions about 75 m per year were found along the centerline of the glacier valley walls moved more slowly O A sudden period of fast movement of a valley glacier surge 39 Sometimes occurs after a long period of little movement I May last several years lce may speed along at more than 6kmyear lOOO times the normal velocity of a glacier 0 The motion of glaciers is responsible for the immense among of geologic work done by iceaierosion transportation and sedimentation 0 Ice is a far more efficient agent of erosion than water or wind Main processes 0 Abrasion o Pluckingavarrying o Other 0 Erosional Landforms A valley glacier carves a series of erosional forms as it flows from it origin to its lower edge 0 Cirque 0 an amphitheater like hollow usually shaped like half of an inverted cone formed at the head of a glacial valley by the plucking and tearing action of ice 0 with continued erosion cirgues at the heads of adjacent valleys gradually meet at the mountaintops producing sharp jagged crests called aretes along the divide o as a valley glacier moves down from its cirgue it makes a new valley or deepens an existing one creating a m o U Shaped valley 0 a deep valley with steep upper walls that grade into a flat floor the typical shape of a valley eroded by a glacier 0 Hanging valley 0 A valley left by a melted tributary glacier that enters a larger glacial valley above its base high up on the valley wall 0 Fjords o A former glacial valley with steep walls and a u shaped profile now occupied by the sea u shaped valley occupied by an arm of the sea Glacial Deposits amp Landforms o Drift 0 Term used for all material of glacial origin found anywhere on land or at sea 0 Till 0 An unstratified and poorly sorted sediment containing all sizes of fragments from clay to boulders and deposited by glacial action 0 Esker o A long narrow winding ridge of sand and gravel found in the middle of a ground moraine 0 Water laid deposit 0 Drumlins o a large streamlined hill of till and bedrock that parallels the direction of ice movement in a continental glacial terrain 0 usually found in clusters 0 look like inverted spoons with gentle slopes 0 ice laid deposit 0 Moraine 0 An accumulation of rocky sandy and clayey material carried by glacial ice and deposited as till 0 Ice laid deposit End moraine large formed at the ice front D After ice meltserseen as ridge parallel to former ice front Terminal moraine at ice front marking farthest advance of ice an end moraine Lateral moraine along the edge of a glacier where it scrapes the side walls of valley D Heavy sediment load eroded from valley walls D When ice melts seen as ridge parallel to valley walls Medial moraine formed as two joined glaciers merge their lateral moraines below junction D Sediment load inherited from lateral moraines D Forms ridge parallel to lateral wall Ground moraine beneath the ice as a layer of glacial debris D Ranges from thick and patchy to thick layer of till 0 Erratics 0 Large boulders often contained in till bc they seem so random compared to the other rocks 12102009 30700 PM Chapter 23 Global Change o Anthropogenic human generated 0 According to Paul Crutzen 0 one of the scientists who discovered the link between chlorofluorocarbons and the ozone o Anthropocene The present human dominated geological human epoch supplementing the Holocene9 the warm period of the past l0 l2 millennia 39 said to have started in the late l8m century when analyses of air trapped in polar ice showed the beginning of growing global concentrations of carbon dioxide and methane D coincided with the invention of the steam engine 0 0 According to Ruddinman o The Ozone Hole Ozone 0 Unstable molecule of 3 oxygen atoms 03 0 Major constitute of smog 39 Undermines health damages crops corrodes materials 0 Six times more abundant in the stratosphere 30km above surface l0ppm than at sea level l7ppm o If all ozone were at sea level it would only from a layer 110quotI inch thick 0 Very thin but ozone layer stratosphere blocks 95 of uv radiation from reaching earth s surface 0 l measurements of Ozone began in l957 Ozone reduction 0 reduced to l3 natural level over antartica 0 7 reduction in tropics 0 l998 largest hole on record 0 US gov official9 people need to wear hats sunscreen and dark glasses 0 Didn t take any responsibility or try to fix it Why was the Ozone hole an important wake up call 0 Stratospheric ozone depletion global phenomenon 0 The protective ozone layer can be depleted by reactions involving human made compounds CFCS o CFCs 39 Chlorofluorocarbons 39 Spray can propellants cleaning solvents etc 39 Sunlight breaks down the CFCs releasing their chlorine D l chlorine molecule can destroy lO0000 atoms of ozone o The hypothesis of the depletion was confirmed in l985 when the hole in the Ozone was discovered 0 Elevated surface levels of UV radiation have been observed to correspond to low stratospheric ozone levels since the early l990s 0 Montreal Protocol 1989 0 Agreement to phase out CFC production 0 Not all countries joined especially developing ones 0 Set up fund to help nations switch to ozone safe chemicals Acid Rain Acidic precipitation caused by the pollution of air with sulfur gases emitted by the smokestacks of power plants that burn coal containing large amounts of the mineral pyrite by smelters of sulfide ores and by some factories and with nitrogen oxide gases emitted by smokestacks and automobile exhausts These gases react with water to form sulfuric acid and nitric acid 0 Causes 0 Burning of coal 39 Most of the sulfurous emissions in North America come from coal fired electric utility plants 0 Pollution of air with sulfur gases emitted from coal burning 39 more than 90 of the sulfur emissions in eastern North America are of anthropogenic descent man made 0 0 lmpacts o Damage to fabrics paints metals and rocks rapidly destroys stone monuments sculptures and buildings 0 Kills sea creatures o Damages forests 0 Acid moisture in air reduces visibility Main Sources of Energy 0 Fossil fuels non renewable energy sources 0 Taken together coal oil and natural gas account for 86 of the energy consumed by the US and the world at large I Coal 31 trillion metric tons left D 200 years worth of coal left D fueled by the industrial revolution D lignite very soft brownish black coal I bituminous soft coal mainly what we use today I anthracite hard coal gt 90 carbon D environmental impacts 0 soot and atmospheric particles 0 sulfur and nitrous oxide 0 C02 0 Acid main drainage 0 Sediment D Disadvantages 39 Oil 1 n 0 Releases 25 more carbon dioxide per unit than oil and 75 more per unit than gas 0 Contains lots of sulfur 0 Causes acid rain 12 trillion barrels worldwide reserves Comes from organic debris of former life plants amp microorganisms Crude oil only forms in a limited range of pressures and temperatures 2 5 km Worldwide reserves of oil are estimated to be l2 trillion barrels 0 Saudi Arabia 7 o US 25 Hubbert s peak 22 0 Hubbert predicted we would reach peak oil production in the US o 1956 0 oil production is decreasing every year negative impacts 0 Oil spills 0 Greenhouse gases 0 Opening of wilderness areas I Natural gas a n 1 Mostly methane CH4 Estimates of resources have risen recently Resources are less depleted than oil bc it is new to the energy scene Emits 30 less carbon dioxide per unit than oil and 40 less per unit than coal Premium fuel 0 Accounts for 24 of all fossil fuels consumed by the US each year O 0 Nuclear O O O O D Reservoirs global D Comes from organic debris of former life plants amp microorganisms D N lOO years left D byproducts of oil production burned off l barrel of oil l house full of natural gas D transportation was problem D wasn t feezable unless we had pipelines D more efficient energy source than coal or oil ltc02 produced D biggest problem LEAKS D Methane 40 times more powerful greenhouse gas than c02 oil and natural gas 39 cleaner energy less c02 particulates and sulfur and nitrous oxides 39 oil forms under window at ltl50 degrees C needs slow cooking I need a trap to collect gas or oil in order for it to be feezable to use 39 easier andor more difficult to transport 39 traps for oil and natural gas D typically trapped behind or underneath some sort of permeable barrier D faults or folds uranium Developed in the last half of the 20m century Slowed down be of safety concerns Supplies 2l of the US s electrical energy used Accounts for less than llOm of the total US energy budget Advantages 39 Low cost Thought it could supply the world with energy for years 0 Disadvantages Possibility of nuclear weapons Toxic waste Reactor safety 0 Alternative 0 Hydroelectric 0 Solar 0 Wind derived from water that falls by the force of gravity and is made to drive electric turbines water falls or artificial reservoirs are used renewable form of solar energy clean risk free cheap disadvantage the environmental costs would greatly exceed the economic gain D dont expect any new hydroelectric capacity to be added through 2020 risk free non depletable current technology to use the sun for energy is inefficient and expensive D BUT it is improving in 2004 accounted for 006 of US energy consumption use of a windmill to drive an electric generator also a form of solar energy growing source of energy good winds only blow across 6 of the lower part of the US D has the potential to supply l5 times the currently energy supply but it would require millions of huge windmills The US uses 22 of world energy in 2004 The US consumes about 45 times more energy per person than the global average 0 Sustainable Development development that meets the needs of the present without compromising the ability of future generations to meet their own needs 0 Key Concepts 0 Supplies of wind and solar energy on accessible land dwarf the energy consumed by people around the globe o the authors plan calls for 38 million large wind turbines 90000 solar plants and numerous geothermal tidal and rooftop photovoltaic installations worldwide 0 the cost of generating and transmitting power would be less than the projected cost per kilowatt hour for fossil fuel and nuclear power 0 shortages of a few specialty materials along with lack of political will loom as the greatest obstacles 12102009 30700 PM Age of the Earth 45 Billion years Oldest Evidence of Life Fossils of primitive bacteria have been found in rocks dated at 35 billion years 3 billion years ago 0 small single celled organisms Age of Complex Life on Earth Between l and 2 billion years ago complex life first formed The first living cells developed 3 billion years ago Humans only developed a few million years ago First animals appeared 6 million years ago Plate Tectonics movement of plates and the forces acting between them The theory proposing that the lithosphere is broken into about a dozen large plates that move over Earth s surface Each plate acts as a distinct rigid unit that rides on the asthenosphere which also is in motion The theory attempts to explain seismicity volcanism mountain building and evidence of paleomagnetism in terms of these plate motions 0 Importance Theory explains o The geologic distribution of earthquakes volcanoes and mountains o The distribution of ancient organisms and mineral deposits 0 Continental drift 0 idea that continents drifted to current positions I evidence jig saw puzzle fit look like some used to be connected before they drifted fossil evidence same fossils found on edges of two separate continents rocks found on edges of two similar continents biogeography paleoclimate Sea Floor spreading o the mechanism by which new seafloor is created along the rift at the crest of a mid ocean ridge as adjacent plates move apart The crust separates along the rift and new seafloor forms as hot new crust upwells into these cracks The new seafloor spreads laterally away from the rift and is replaced by even newer crust in a continuing process of plate creation Rate of plate movement 0 Types of plate boundariesWhat happens at these boundaries 0 Divergent boundaries 39 Plates move apart and new lithosphere is created new crust forms 39 Oceanic Plate Separation D On the seafloor the boundary between separating plates is marked by a mid ocean ridge that exhibits active volcanism earthquakes and rifting caused by tensional stretching forces that are pulling the plates apart 39 Continental Plate Separation D Characterized by rift valleys volcanic activity and earthquakes distributed over a wider zone than oceanic D Separate enough for new seafloor to form along the axis 39 lE mid ocean ridges o Convergent Boundaries 39 Plates come together and one is recycled back into the mantel 39 Crust is destroyed 39 Ocean Ocean Convergence D One subducts beneath the other forming trench on one side and volcanic island arc on the other 39 Ocean Continent Convergence D Oceanic plate subducts under continental plate bc continental crust is lighter and less dense D Great earthquakes and volcanoes 39 Continent Continent Convergence D Plates break up and collide forming mountains o Transform Fault Boundaries 39 Plates slide horizontally past each other plate area remains constant 39 Crust is neither created nor destroyed 39 Typically found along mid ocean ridges 39 lE San Andres fault 3 Main Types of Rocks amp How They are Used by Geologists o Metamorphic O O O 0 Rock formed by the transformation of preexisting solid rocks under the influence of high pressure and temperature Mineralogy texture and chemistry are altered Where does it occur Between surface and 30 km depth Geologists use them to record a history of pressure and temp changes 0 Sedimentary O O 0 Rock formed as the burial product of layers of sediments such as sand mud and calcium carbonate shells under the sea whether they were laid down on the land or form as rocks undergo weathering and erosion form by lithification of sediments after burial under additional layers of sediment O O I either by compaction grains are squeezed together by the weight of overlying sediment into a mass denser than original or cementation mineral precipitate around deposited particles and bung them together derived from the weathering and erosion of tocks exposed at earth s surface geologists use them for 39 historic record of earth I record of surface conditions 39 paleoenvironments 39 paleogeography o Igneous O O O O Volcanoes amp Earthquakes Climate Change Rock formed by the solidification of a magma before or after it reaches the surface When magma cools slowly in the interior more time to crystallize 399 course grained intrusive ie granite When magma erupts rapidly no time to develop so the crystals are very small 399 fine grainedglassy extrusive ie basalt geologists use crystal size to distinguish between the two major types of igneous How They Relate to Plate Tectonics amp How they Relate to Plate Tectonics tectonic Historic How We Reconstruct Past Climate Magnitude of Climate Change Causes of Climate Change 12102009 30700 PM oil and natural gas 0 cleaner energy less c02 particulates and sulfur and nitrous oxides 0 oil forms under window needs slow cooking at ltl50 degrees C 0 need a trap to collect gas or oil in order for it to be feezable to use 0 easier andor more difficult to transport traps for oil and natural gas 0 typically trapped behind or underneath some sort of permeable barrier 0 faults or folds Hubbert s peak 0 Hubbert predicted we would reach peak oil production in the US o 1956 0 oil production is decreasing every year Global Hubbert s peak 0 60 years of global resources for petroleum left The US consumes 25 of the worlds oil 0 We consume so much because our price per gallon is so much less than in Europe etc Oil environmental impacts 0 Oil spills 0 Greenhouse gases 0 Opening of wilderness areas Natural gas 0 Reservoirs global o N l00 years left 0 byproducts of oil production burned off 0 transportation was problem l barrel of oil l house full of natural gas 0 wasn t feezable unless we had pipelines 0 more efficient energy source than coal or oil ltc02 produced 0 biggest problem LEAKS o Methane 40 times more powerful greenhouse gas than c02 Sustainable energy 0 Read THE PATH TO SUSTAINABLE ENERGY BY 2030
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