Geology Exam 3 Review
What is a cirque?
A bowl-shaped depression that develops on the side of a mountain at the head of a glacier.
What is the difference between a glacial and interglacial period? What is the relationship between climate change, glacial activity, and changes in global sea level?
A glacial period is the period where global advancement occurs, while an interglacial period is warmer, glaciers retreat, and sea levels rise. So glaciers are retreating and causing sea levels to rise both because of the interglacial period and because of fossil fuel combustion. This is causing an even greater rate of sea level rise.
What is a glacier? What conditions are needed for one to form?
A glacier is a mass of ice that moves under its own weight, under the force of gravity. Conditions- - cold enough climate for snow and ice year-round - appropriate combo of altitude and latitude - gentle slope
What is an arête?
A knife-edge ridge of rock that separates two adjacent cirques.
What is shale gas, and how is it typically mined? What are some of its environmental impacts?
A large resource is shale gas. The fine sediments that are later lithified to become shale are often rich in organic matter. Over time, heat and pressure may break this down into natural gas. Most shales are low in permeability, so extracting the gas was once not possible. However, technology to increase permeability, called hydraulic fracturing, or fracking, which can drill horizontally along shale beds to facilitate fracking and gas extraction, has improved to the point that the gas in many shapes can be counted in our reserves. Fracking activity has raise concerns about induced seismicity and possible groundwater pollution.
What is a horn?
A pointed mountain peak surrounded by at least three cirques.
What is the difference between a mineral reserve and a mineral resource?
A resource is any useful economic commodity, one that changes with time or context. A reserve is a portion of a resource that has been discovered and currently available to be extracted.
What is the difference between an alpine and continental glacier? Which are more numerous today? Where are continental glaciers found today?
Alpine glacier- numerous today, also called mountain or valley glaciers - occupy valleys in mountainous terrain at high altitudes Continental glacier- larger and rarer, also called ice caps or ice sheets. can span entire continents and reach thicknesses greater than one kilometer. Greenland and Antarctic ice sheets.
What is the difference between how a U-shaped vs a V-shaped valley formed?
An alpine glacier carves its own U-shaped valley. The valley carved out by a stream is typically V-shaped. Glacial erosion modifies valleys from V shaped to U shaped.
What is an ore? What is a concentration factor used for and how is it determined?
An ore is a rock or metallic mineral that can be mined for a profit. A concentration factor is the concentration necessary for profitable mining, determined as a ration: the concentration of the metal in the ore deposit/the average concentration of the metal in the crust = concentration factor
How does rising CO2 in the atmosphere affect ocean acidity levels? What implications does this have for limestone reefs and photosynthetic marine microorganisms?
As Co2 levels build up in the oceans, the oceans become more acidic. Co2 + water leads to carbonic acid, which leads to hydrogen ions and bicarbonate. Carbonic acid and hydrogen ions both lower pH levels, making solutions (like ocean water) more acidic. Increased acidity levels weaken or dissolves outright the limestone shells of marine invertebrates such as coral and phytoplankton, species that essentially form the base of entire ecosystems.
How does wind influence upwelling along a coast, and what is its effect on local ecosystems? How does El Nino disrupt this system along the western shore of South America?
As winds blow offshore, the warm surface water is pushed away from the coast, and the deeper, cooler water upwells toward the ocean surface. This water is nutrient rich, and in many regions of the world where upwelling occurs diverse, aquatic, ecosystems grow and thrive. El Niño refers to a periodic halt in this upwelling, where the fertile cold waters no longer rise up along the western South American coasts. The reason as to why this occurs is not well understood, though it seems to be part of the El Niño Southern Oscillation Cycle (ENSO). The result of the El Niño event causes large scale changes in the path, frequency, and intensity of Pacific storms and the timing of the monsoon season. There is concern that a rise in global temps will cause El Niño events to occur with greater frequency.
Why are biofuels called unfossil fuels? What is the difference between waste-derived and alcohol-derived fuels? What crop is used to create ethanol? What are some benefits and drawbacks to relying on ethanol as an alternative fuel source?
Biofuels are called "unfossil fuels" because they are created from recently dead organisms, as opposed to long-fossilized ones. Waste derived fuels- burning waste plant materials, either crop waste or urban refuse to provide heat for electric generating plants. Some waste-derived fuels are liquids. Research is ongoing to derive liquid fuels from animal waste, such as manure, which is rich in organic matter. Fuels can be derived from vegetable oil or animal fats to run diesel-powered engines. Another waste-derived biomass fuel growing in use is "gas from garbage," or biogas. Landfills and manure piles can contain large amounts of trapped methane gas that develop when organic waste breaks down. This methane can then be used to supplement the natural gas supply. Alcohol fuels- most gas contains about 10% ethanol, an alcohol produced from domestically-grown corn. The reason for the mix is that the more alcohol that can be used, the further the gas supply can be stretched, lessening our reliance on imported fuels. While vehicles can be designed to run entirely on 100% alcohol, more commonly the practice is 85% alcohol, 15% gasoline. The concern about ethanol as a fuel source is that it can take more energy to grow and harvest the corn than is released from burning the ethanol. A further concern is that food is being grown for use other than to feed those who might need it, and has led to pressure to grow crops on land that might be normally unsuitable or unsustainable for short or long-term use. These reasons are why researchers are trying to produce ethanol from waste organic matter instead of from living crops.
What is coal and how does it form? How does the chemical composition of coal differ from that of oil and gas; and how does the origin of coal differ from that of oil and gas?
Coal is a combustible rock used as fuel. Coal forms from the remains of land plants that died in swampy environments, often hundreds of millions of years ago, under anaerobic conditions. Coal is a complex mixture of many different long-chain hydrocarbons. Oil is also a mixture, but of somewhat shorter hydrocarbon molecules that can be separated into products like gasoline, kerosene, and diesel fuels. Coal is formed from land-based plants in bogs and coastal swamps, while oil and gas are derived from tiny marine organisms, such as algae and phytoplankton.
What are the main grades of coal, and how are they defined? What is the estimated reserve supply of coal in the US?
Coal is classified based on carbon content, sulfur content, and combustion values (calories). From low grades to high grade they are: 0. Peat- formed at the earth's surface, combustible. With burial and more heat, pressure, and time, peat gradually dehydrates and forms... 1. Lignite- soft, low carbon content, high moisture content, low heat content- i.e. does not release so much heat when burned relative to higher grades of coal 2. Subbituminous 3. Bituminous 4. Anthracite- hard, high carbon content, low moisture content, high heat content Estimated US coal reserves are over 250 billion tons; total resources ~ 4 trillion tons
What is cap rock and how does it influence oil production?
Commercially, the most valuable oil deposits are those in which a large quantity of oil/gas has been trapped by and concentrated in a layer of impermeable rocks that cap it from above: the impermeable layer is called cap rock. The Saudi Arabian oil fields are an example of such a deposit.
What was the intention behind creating the Strategic Petroleum Reserve?
Concerns about dependence on imported oil led to the establishment of the Strategic Petroleum Reserve in 1977. It was established to provide a cushion in the event of disruption of imports of oil.
What are some risks associated with fission nuclear reactors?
Core meltdown- this occurs when the flow of cooling water to the reactor core is interrupted. The core overheats and turns into a molten mass that melts its way out of the containment building and into the environment, releasing high levels of radiation.
What defines a desert? What are some ways in which deserts form naturally? What is desertification and why is it a cause of environmental concern?
Desert- any area in which few forms of life can exist because of lack of water, permanent frost, or absence of soil. Deserts are found at all latitudes- the largest are subtropical but they can also be found at the poles. Causes of natural deserts: High surface temperatures- the air at the equator results in desert environments due to cooler air warming as it reaches the surface, taking with it much of the moisture, causing rapid evaporation. Topography- mountain ranges that lie in the path of air currents may push the air in higher altitudes as the air rises over the range, causing the air to cool and for it to lose its moisture (which precipitates out as rain). As a result, one side of the mountain range is wet, but the opposite side is dry, forming a rain shadow. Desertification- the rapid development of deserts caused by the impact of human activities, usually as a consequence of land-use practices. Removing native vegetation and replacing them with crops leaves the land vulnerable to degradation during drier conditions; similar results with training livestock. Desertification reduces the overall amount of arable land on which the world depends for food.
What is kimberlite? For what mineral is it known?
Diamonds are mined from an igneous rock called kimberlite, which forms large pipe-like intrusions that rise up from the mantle.
What is a dune? How do they move?
Dune- low mound or ridge made up of sand. Wind deposition- this creates dunes, usually made of sand, but snow dunes are possible. The orientation of dunes reflects the prevailing wind direction, with the shallower slope side facing upwind. Dune migration- if there is a strong enough prevailing wind direction, a dune can migrate: its particles get blown up the side of one shallower surface and slide down the steep slip face.
What are some of the environmental impacts of coal mining? What is done with the waste product, ash?
Environmental impacts of coal mining include- natural gas explosions, underground fires in coal seams that can run for decades, sulfur left behind in waste rocks in spoil banks (forms sulfuric acid when mixed with water), and acid runoff. Coal leaves behind a solid waste, called ash, which needs to be disposed of safely, since it can contain trace amounts of toxic materials, such as arsenic, lead, selenium, and uranium. Presently, it goes into landfills or containment ponds.
What are evaporite deposits? In general, how do they form, and what type of ore deposits do they leave behind?
Evaporite deposits are salt deposits that form when a body of shallow seawater gets "trapped" (cannot connect back to the ocean) and dries up: the water evaporates and a layer of salt is left behind. Halite and gypsum are two minerals that are mined from evaporite.
What were the circumstances behind the Exxon Valdez and Deepwater Horizon incidents? What were some of the options used in the clean-up of the spills?
Exxon Valdez- tanker loaded with 1.2 million barrels of crude oil from Alaska's North Slope, ran aground on Bligh Island. Response to this spill was delayed for ten to twelve hours after the accident. In order to try and clean this up, they tried chemical dispersants and burning the spill, but neither worked and the oil emulsified with the water. It became clear that only slow degradation would work. However, as an experiment, scientists sprayed the beaches in the area with fertilizer, and those beaches were cleaner than untreated ones later. Deepwater Horizon- drilling rig exploded and burned for two days. The remains of the structure sank to the bottom of the Gulf of Mexico and oil spread all over the water. Some of the above methods were applied, as well as Skimmer ships that tried to collect the oil, and dispersant applied to the surface slick.
What is fission? What isotope of what element is used in the production of nuclear energy?
Fission involves the splitting of an atom's nucleus into smaller ones. This releases energy. Fission is the only commercially feasible process. In fission, the nucleus of interest in modern nuclear reactors is the isotope uranium-235, with 92 protons and 143 neutrons.
How does a glacier form? What is the difference between the zone of ablation and the zone of accumulation?
For glaciers to form, the following conditions must be met- Precipitation- glaciers are reservoirs of frozen water A higher rate of snowfall than melt each year, allowing the glacier to grow over time Mountains- most glaciers begin in the mountains as snow patches that survive the summer. This is favored on north-facing slopes Gentle slope- if the slope is > 30 degrees, avalanches may form, clearing the glaciers away Zone of accumulation- snowfall adds ice to the glacier Zone of ablation- removal of ice, involves sublimation, melting, and calving.
What are some examples of fossil fuels? Why are they called fossil fuels? What two elements are fossil fuels predominantly composed of? What percentage (%) of our nation's energy supply comes from fossil fuels versus, say, hydropower / nuclear power? Are fossil fuels renewable?
Fossil fuels are nonrenewable energy sources that form from the remains of once-living organisms (they are formed from fossils). Fossil fuels include oil, natural gas, and coal. The US relies on fossil fuels for about 79% of its total energy consumption. Fossil fuels are mainly made from Hydrogen and Carbon.
What is geothermal energy? How do we make use of it? For large-scale use, where do we find an appropriate heat source? What are some drawbacks to geothermal energy?
Geothermal heat pumps take advantage of the fact that rocks are a poor conductor of heat, and the pumps are suitable for individual homes or for single building office dwellings. Pipes are drilled deep into the soil and circulate water down into the earth and then back up: on a cool day, the cold water is warmed by the Earth, and that can be used to heat a home. On a warm day, the warm water is cooled by Earth, and that cooled water can be used to heat a home. No CO2 emissions are generated. Geothermal power plant locations are near sites of active volcanism because natural heat production is not evenly distributed around the earth. Drawbacks to geothermal energy: Installation cost- 3x as much as a heating/AC unit The warmed geothermal waters may contain contaminants that can damage ground or surface waters The heat source cools off with time, limiting the life of the facility to a few decades The power plants are not efficient for transmitting the power elsewhere; it is best used for nearby sites Some regions have protected status, like Yellowstone. This region has the highest concentration of thermal features of any geothermal area in the world, but plants cannot be built there
What are glacial striations?
Glacial activity often leaves grooves/scratches in rocks called glacial striations that form parallel to the flow direction of the glacier.
By what process do glaciers move/slide?
Glaciers move by internal deformation of the ice, and by sliding over the rocks and sediments at the base. Internal deformation occurs when the weight and mass of a glacier causes it to spread out due to gravity. Sliding occurs when the glacier slides on a thin layer of water at the bottom of the glacier.
What is albedo? What substances have high albedo and why? How does albedo influence climate change? What are some examples of positive feedback and negative feedback regarding climate change?
Glaciers, being white in color, typically help reduce global warming levels by reflecting sunlight back into outer space. This reflectivity is called albedo. Light colored surfaces have high albedo and dark colored surfaces have low albedo. Glacial ice has a high albedo. The more glaciers retreat, the lower the albedo, and the more quickly the Earth warms up. This is called a positive feedback cycle- the warming trend reinforces itself. It is possible that as global temperatures rise, large-scale storms will become more frequent, and the increased cloud-coverage would potentially slow the rate of global warming. This is an example of negative feedback- the warming induces changes that encourage the opposite.
What are the major greenhouse gasses? Of these, which are the most abundant greenhouse gasses?
Greenhouse gasses trap infrared rays and promote the warming of the atmosphere. The current greenhouse effect is caused by many atmospheric gasses, including: water vapor, carbon dioxide, methane, nitrogen oxides, and CFCs. The most abundant are water vapor and carbon dioxide.
How might energy be harnessed from the oceans?
Harness energy from the tides- at least a 5-meter difference needed between high and low tide to be effective for generating electricity, in addition to a bay/inlet with a narrow opening that could be dammed to regulate the water flow in and out. Ocean thermal energy conversion (OTEC)- still in development stages, this approach takes advantage of temperature differences between warmer surface waters and cooler deeper waters. Harness energy from the waves- even the bobbing of water in a wave can be harnessed to generate electricity- the bobbing can push water through a turbine.
Igneous rocks and magmatic deposits can produce large ore repositories under certain tectonic conditions. What might some of these conditions be?
Igneous rocks and magmatic deposits are commonly found along plate boundaries, or areas with extensive magmatic activity.
What is the relationship between snow, firn, and ice?
Initially, loose snow is 90% air. As more snow is deposited on top of it, the snow becomes denser and more compacted as air is driven out, and turns into firn (25% air); and eventually recrystallizes to form glacial ice (20% air). Glacial ice consists of interlocking ice crystals. Eventually, if there is a slope, gravity pulls a mass of ice downslope, creating a glacier. Firn is granular snow that has not yet been compressed into ice.
What are banded iron deposits and why are they a valuable economic resource?
Iron ore deposits come primarily from some of the world's oldest known sedimentary rocks: banded iron formations. These ancient deposits consist of alternating layers of sedimentary rock and iron oxides. They initially formed in the sea, but are now found and mined above ground. In the US, these deposits are found around Michigan and the Great Lakes, and they were responsible for fueling the rise of the iron industry in many cities.
What is a lateritic soil? In what regions are such soils found? Why are such soils not advantageous for long-term farming?
Lateritic soil- heavily leached, very oxidized (hence red in color), an extreme pedalfer. Common in rainforests- laterite soils develop in tropical climates with high temperatures and heavy rainfall. These soils are not advantageous for long-term farming because the soil is highly leached, so there are few nutrients left in it. Also, when laterite soil is exposed to sunlight, the soil clumps up like a brick, resulting in poor irrigation.
What are some of the benefits/drawbacks to using coal? How does the Co2 emission output of coal compare to that of oil and gas?
Limitations of coal use: not as versatile as oil/gas (can't fill up a car or plane with coal). It's polluting- coal was once used to power steamboats and steam train engines but Diesel engines became more popular in part due to being a cleaner fuel. Also, coal is not the most convenient fuel for home heating. The burning of coal produces Co2- far more Co2 than either oil or natural gas.
What is loam?
Loam- refers to a soil that has a roughly equal mix of sand and slit, and 10-30% clay.
How are hydrothermal deposits formed? What type of metals do they produce? What are black smokers?
Magmas contain water and other fluids that can seep into the cracks of surrounding rocks because of the pressure they are under. These fluids, often super-heated, can leach out minerals and ions from the rocks through which they pass. As the fluids cool, they deposit their minerals, forming a hydrothermal deposit. Because sulfur is a common component of these fluids, the ore minerals found in hydrothermal deposits are called sulfides, e.g. copper is mined from copper sulfide, lead is mined from lead sulfide, etc. These minerals all come from hydrothermal deposits. Hydrothermal deposits are also a common feature of "black smoker" vents- undersea hydrothermal vents that spew metal rich sulfides onto the sea floor.
What is coal-bed methane?
Methane gas occurs naturally in coal seams and previously was released during mining as a waste-product (it is both toxic and explosive). It was later deemed desirable for extraction, adding to the US gas reserves.
Are minerals renewable resources?
Minerals are nonrenewable resources
What are some environmental/health issues associated with underground mining operations?
Mining is a dangerous activity. Both underground and surface mines can be sources of water pollution. Near-surface underground mines occasionally have collapses years after abandonment, when supporting timbers have rotted away or groundwater has enlarged the underground cavities. Sometimes active mines collapse as well.
Who was Charles Keeling and what was his contribution to the study of climate change? Why are there fluctuations in the curve over the course of a single year?
Modern CO2 levels were first measured in 1958 by Charles Keeling. There are fluctuations in the curve because there are differing levels of photosynthesis based on the season.
How do the future prospects look for oil and gas?
Most places that are not yet explored for oil are very unpromising. The costs of exploration have gone up as well. Nearly half of exploratory wells come up dry. US reserves continue to decline. Essentially, future prospects are not looking good.
What are oil sands (also called "tar sands")? What is the name of the petroleum product that they produce? What country possesses most of the world's oil sand reserves and where is it located?
Oil sands, also known as tar sands, are sedimentary rocks containing a very thick, semisolid, tar-like petroleum called bitumen. The heavy petroleum in oil sands is believed to be formed in the same way and from the same materials as lighter oils. In Canada, the extensive Athabasca oil sand in the province of Alberta is estimated to contain over 170 billion barrels of recoverable bitumen reserves (about 70% of the world's known oil-sand reserves).
What are oil shales? Where is the major US resource located and what type of petroleum deposit is formed there?
Oil shale- poorly names because it is sedimentary rock, isn't necessarily shale, and the hydrocarbon in it is not oil. The potential fuel in an oil shale is a sometimes-waxy solid called kerogen, which is formed from the remains of plants, algae, and bacteria. The US possesses about 75% of the world's known oil shale resources and most of it (70%) lies in the Eocene Green River Formation, a 40-million year old rock layer that runs through Colorado, Wyoming, and Utah. The formation represents an ancient lake deposit.
What are the two categories of surface mining? What are some of their environmental hazards?
Open-pit mining (and quarries): extracts rock either intact (building) or crushed (making cement, roads, etc) Practical when the ore is located near the surface End product leaves a large hole, which may fill with water, which may carry pollutants elsewhere Sulfide minerals in the open pit mine react with oxygen and water to form sulfuric acid as a weathering product, creating acid runoff water Strip mining: Commonly used to extract coal, but also limestone and other minerals Practical when ore is near the surface and runs in layered seams When mining operations are completed, the land is reclaimed and restored to habitable levels (in the past, the waste rock and soil were simply dumped back on top as soil banks, which then led to chemical and sediment pollution)
What is the difference between passive and active solar heating?
Passive solar heating- requires no mechanical assistance: making use of an architectural design that enhances solar energy absorption. Active solar heating- involves pumps that circulate solar-heated water. The water is then stored in a tank to serve both as a space heater and a hot water supply.
What does peak oil production refer to? Do we run out of oil at that point? What is expected to happen to the price of oil after this occurs? Globally, around what year is peak production predicted to occur? When did it occur in the US? Who was M. King Hubbert?
Peak oil production is the moment at which extraction of petroleum reaches a greater rate than that at any time in the past and permanently starts to decrease. The decrease is predicted to be due to a transition towards renewable resources and a shrinking supply of fossil fuels. M. King Hubbert accurately predicted the peak of US oil production back in the 1950s- he developed equations referred to as Hubbert curves, or peak oil curves, that showed how production of resources changed over time. The peak of oil production in the US happened in 1970, as predicted by Hubbert. Oil production globally is predicted to peak between 2010 and 2030.
What is the difference between a pedalfer soil and a pedocal soil?
Pedalfer soils (more leached)- reflect soils developed in more humid (wetter) regions. These soils are more leached, leaving the B horizon more enriched in aluminum and iron minerals. These soils are usually more acidic. In North America, these soils are found in higher-rainfall areas- eastern US and most of Canada. Pedal soils (less leached)- reflect soils developed in drier regions (less rainfall). These soils are less leached, so soluble minerals like calcium carbonate remain in the B horizon. These soils are usually more alkaline (less acidic) due to the presence of calcium carbonate. In North America, these soils are found in the southwestern US.
What is permafrost and why is it of concern with regard to global warming?
Permafrost is permanently frozen ground, seen in northern latitudes above 60 degrees, underlying about 20% of the land area in the world. Changes in permafrost affects the distribution of surface water and groundwater.
What is the difference between petroleum, oil, and natural gas? What is the chemical make-up of natural gas?
Petroleum is a hydrocarbon, an organic compound of hydrogen and carbon. Oil is a liquid petroleum, made up of a variety of liquid hydrocarbons. Natural gas is petroleum in the gaseous phase, including the compound methane.
In general, how do photovoltaic cells work?
Photovoltaic cells are a way to produce electricity using sunlight. The cells consist of two layers of semiconductor material oriented to produce an electric current when struck by the sun's rays. Like solar heating, they do not emit pollutants, and they have no moving parts.
What is the difference between physical and chemical weathering? How do these differ from erosion?
Physical/mechanical weathering- anything that breaks up rock without altering its composition- i.e. ice, wind, water. This type of weathering breaks larger chunks of rock into smaller ones, increasing the exposed surface area. Chemical weathering- breakdown of minerals either by chemical reaction with water, with other chemicals dissolved in the water, or with gasses in the air. Weathering and erosion are different because weathering is the breakdown of rocks or minerals in place, while erosion is the physical removal of material from one place to another.
What are placer deposits? What type of ore deposits are they known for, and in what kind of depositional environment do they form?
Placer deposits are formed by flowing water, so streams or along coasts. As water velocity slows down, e.g. at a point bar in a stream, minerals may, over time, settle out and accumulate in these regions. They are known for placer deposits of gold, from the Sierra Nevadas in the gold rush of 1849.
How does mining contribute to pollution? What is the environmental concern regarding smelting?
Processing generally involves crushing/grinding the ore. The fine waste materials, or tailings, that are left over may end up heaped around the processing plant to weather and wash away. Depending on the nature of the ore, rapid weathering of the tailings may produce acid drainage and leach out harmful elements, which contaminates surface water or groundwater. The chemicals used in processing are often hazardous also. Smelting to extract metals from ores may, depending on the ores involved and on emission controls, release arsenic, lead, mercury, and other potentially toxic elements along with exhaust gasses and ash.
What are some of the pros and cons of nuclear energy?
Pros- nuclear plants have lower fueling and operating costs than coal-fired plants, fuel can be easily stockpiled for these plants. Cons- nuclear plants are costly to build and take a long time, there is public opposition to nuclear plants, there is danger of reactor accidents.
What are some of the pros and cons of relying on solar cells as an alternative energy source?
Pros- sunlight is a free, inexhaustible resource. It produces no hazardous waste or air pollution, Cons- Cost- though the prices have dropped considerably to have solar cells in one's home, the cost is still high, and solar cell companies are still working on producing viable business models to stay in business. Efficiency- current solar cells are designed to only make use of a small fraction of the sun's rays, preventing some industrial operations from using solar for energy-intensive applications. Scale- using solar cells at a larger scale would take a large commitment of both land and mineral resources. Storage- the ability to store solar electricity is not practical beyond the homeowner stage.
What are some risks associated with spent fuel and nuclear waste handling?
Radioactive material remains radioactive- it cannot be broken down into non-radioactive components Lack of permanent long-term storage- all of the world's radioactive waste is in temporary storage. Decisions have not been made as to how to store radioactive waste long-term. In the US, much of the high-grade nuclear waste is stored at the reactor site. Decommissioning- nuclear power plants built in the US in the 1970s have been in operation for 40 + years. Reactors are aging and the cost to take one out of operation, break it down, and deliver the most radioactive elements of the plant to radioactive waste disposal sites takes years of work and can tally nearly $1 billion per plant.
What is the difference between primary, secondary, and enhanced recovery of oil and gas?
Recovery using no techniques beyond pumping is primary recovery. When the flow falls off, water may be pumped into the reservoir, filling empty pores and buoying up more oil to the well (secondary recovery). Primary and secondary recovery together extract an average of 1/3 of the oil in a given trap. Then, 2/3 of the oil is left in the ground, making enhanced recovery methods gain interest. Enhanced recovery comprises a variety of methods beyond secondary recovery. Permeability of rocks can be increased by fracturing, using explosives, or even under high water pressure. Carbon dioxide gas under pressure can be used to force out more oil. Hot water or steam may be pumped underground to warm thick, viscous, oils so that they flow more easily and can be extracted more completely.
What is the difference between the rigid zone and the plastic zone of a glacier? At what depth is the boundary between the two zones?
Rigid zone- less than 60 m away from the surface (top), where the ice breaks into blocks. Plastic zone- depths greater than 60 m away from the surface, ice doesn't crack at this zone. Plastic deformation-occurs at depths of 60 m in a glacier, ice grains change shape very slowly as the glacier moves, and/or new grains grow while old ones disappear. Above this, ice is too brittle to flow, and instead moves by cracking; the cracks are called crevasses. The ice doesn't crack below depths of 60 m: the 60 m boundary is the brittle-plastic transition.
Where are some geographic areas within North America whose landscapes have been influenced by glacial activity?
Rocky Mountains- many of its peaks and valleys were glacial carved. Great Lakes- the lakes occupy basins carved and deepened by glaciers and filled with glacial meltwater. Canada's Hudson Bay- depression formed by the weight of the ice sheets and flooded with seawater after the ice melted away. Drainage of the Mississippi River- in part was formed by meltwater from retreating ice sheets. The sediments carried with that meltwater are responsible for the fertility of the Midwestern farmland, and supply the groundwater tapped today for irrigation.
What is glacial till?
Sediment transported by ice and deposited beneath, at the side, or at the toe of a glacier.
How much have Co2 levels risen since the industrial revolution? How much has global surface temperature risen since the industrial revolution?
Since the onset of the Industrial revolution in the late-1700s, Co2 levels have steadily been rising in our atmosphere, upwards of 40% and its levels continue to rise. Since the mid-1800s, the Earth's surface temperature has risen about .85 degrees Celsius. This may not sound like much, but it is having a dramatic impact around the world.
What are some ways that future mineral-resource shortages might be averted... or ways in which the projected lifetime of reserves could be extended?
Some relief in the overall supply picture can be anticipated from the economic component of the definition of resources. For example as reserves are depleted, the law of supply and demand will drive up minerals' prices. This, in turn, will make what are presently sub economic resources profitable to mine; some of those deposits will effectively be reclassified as reserves. Continued exploration can be expected to location additional resources as well. One way to extend nonrenewable resources would be to reduce consumption rates. Another way is by making substitutions, like replacing a very rare metal with a more abundant one. The most effective way to extend mineral reserves, for some metals, is through recycling.
What are spoil banks? What are tailings? What is heap-leaching? How do these potentially lead to a source of pollution?
Spoil banks- bank composed of excavated earth (waste rock and soil). These could lead to pollution because chemical and sediment pollution can runoff from them. Tailings- mineral processing to extract a specific metal from an ore involves crushing the ore. The waste materials from this process are called tailings. Weathering of the tailing may produce acid drainage, similar to spoil banks of strip mines, and leach out harmful elements such as uranium, mercury, etc that contaminate ground waters. Heap-leaching- an industrial mining process used to extract metals and other compounds from ore using a series of chemical reactions. Cyanide solutions are used to percolate through tailing piles to dissolve out metals like gold. Spills and contaminations can result from this process.
Why is sulfur content significant with regard to coal? What are scrubbers?
Sulfur content is significant with regard to coal because it is an additional pollutant. When sulfur is burned along with coal, a poisonous sulfur gas is produced called sulfur dioxide. This gas reacts with water to form sulfuric acid, and mixes with rainwater to form acid rain. Removing sulfur from the coal is desirable, but adds an additional expense, involving the use of scrubbers. Scrubbers are put in exhaust stacks to spray down the gaseous emissions before they are released into the atmosphere, essentially filtering the gas of pollutants.
What are some of the challenges involved in land reclamation once the mining operation is completed?
Surface coal mines are refilled with soil when they are reclaimed, but the issue of water availability to support plant re-growth becomes an issue with drier areas out west. Another issue with land reclamation hinges on the wording of the 1977 Surface Mining Control and Reclamation Act that states the mine be restored to its "approximate original contour". Surface mining operations in the Appalachians, and elsewhere, sometimes require the removal of an entire mountaintop, a procedure done with explosives and earth-moving equipment. The valleys are then filled with the removed, unused product. To what extent is the original mountaintop able to be restored...
What are the three primary soil horizons and how do they differ? What does it mean to say that a soil is leached?
The A horizon has three subdivisions- O, A, and E. O- organic layer- consists of organic matter, or humus. The O and A horizon together make up topsoil, the fertile portion of soil that farmers till for planting crops. Below the A horizon is the E horizon. The O, A, and E horizon form the zone of leaching because rainwater percolates through this initial layer, dissolves soluble minerals, and carries them away. The "E" in E horizon stands for eluvium. The B horizon lies in the zone of accumulation. The B horizon is called the subsoil, where ions, clay minerals, and iron oxides accumulate. Organic matter from the surface is largely absent from this layer. The C horizon consists of material from the underlying bedrock that has undergone some weathering. It consists mostly of broken-up bedrock. When soil loses essential water-soluble nutrients needed for crop growth due to excessive rain or irrigation, the process is referred to as leaching.
Where is the biggest oil field in the US? What is the significance of the NPRA and the ANWR (and what do the acronyms stand for?), and what are some of the issues regarding to drill or not to drill in these areas? About how long does it take to develop a new oil field? How is oil transported from the Alaskan North Slope to the southern part of the state?
The Prudhoe Bay field on the North Slope of Alaska is the largest US oil field ever found. NPRA- National Petroleum Reserve Alaska. ANWR- Arctic National Wildlife Refuge. These are significant because they are federal lands, but their geological similarities to Prudhoe Bay suggest that they have oil and gas reserves. There are probably about 7 billion barrels of oil in each area. Development of oil fields can take about 10 years. Those opposed to drilling note the environmental fragility of alpine ecosystems, the biological richness of the area, and the fact that the US consumes over 7 billion barrels of oil annually (so this is a relatively small amount of oil). Oil is transported from the Alaskan North Slope to the southern part of the state through the Trans-Alaska Pipeline 1. the National Petroleum Reserve-Alaska (NPRA), established in 1923 (Harding administration). The NPRA is west of Prudhoe Bay and exploratory drilling has confirmed the presence of oil and gas. 2. the Arctic National Wildlife Refuge (ANWR), established in 1980 (Carter administration). The ANWR lies east of Prudhoe Bay, making up the northeast corner of Alaska, and is thought to hold billions of gallons of oil. Both the ANWR and the NPRA are run by the Bureau of Land Management (BLM), part of the US Department of the Interior, run by David Bernhardt, Secretary.
How many billions of barrels of oil does the US consume per year, and how much overall energy does it supply to our total needs? About how much oil (%) do we import, and what are the primary countries from whom we import oil?
The US consumes about 7.1 billion barrels of oil each year, to supply about 37% of all energy used. Net imports are about 25% of consumption, and principal sources of imports are Canada, Saudi Arabia, Venezuela, Mexico, and Colombia.
What is the terminal moraine?
The debris deposited by the furthest extent of glacial ice is called the terminal moraine.
What are Milankovitch cycles and, in general, how are they thought to contribute to Ice Ages?
The earth's orbit around the sun is not perfectly circular, so the distance between sun and earth is not constant, and the shape of the orbit varies. Axial tilt also varies somewhat over time relative to the earth's orbital plane, as does the orientation of the axis in space. Such changes do not significantly change the total amount of sunlight reaching the earth, but they do affect its distribution, the amount of sunlight falling at different latitudes (and therefore the relative surface heating expected), and the time of year at which a region receives its maximum sunlight. Together, they result in long-term cyclic variations, over time scales of tens of thousands of years, in local isolation (incident sunlight) named Milankovitch cycles after the scientist who recognized them in the early 20th century. Milankovich cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. These are thought to be a potential cause for the Ice Ages.
Is it possible to simply rely on the geothermal gradient to draw heat?
The geothermal gradient is the rate of increase of temperature with increasing depth in the earth. It is unlikely that there would be commercial development with just relying on the geothermal gradient for heat. There would be substantial technical problems with developing this resource.
What are the US's predominant mineral resources (and are they metal-based?)? Of the metal-based minerals, which is our most abundant ore?
The greatest mineral resources consumed in the US are iron (used for steel products), aluminum (mined from bauxite and used for canning and construction), copper (electricity conductor), zinc (used as a coating on steel cans), and precious metals. The most abundant ore in the US is molybdenum.
What is the greenhouse effect?
The greenhouse effect is a process that occurs when gasses in earth's atmosphere trap the sun's heat (longwave radiation). This process makes earth much warmer than it would be without an atmosphere.
What is the difference between source rock and reservoir rock?
The majority of petroleum originates in fine-grained clastic sedimentary rocks called source rocks. From there, the oil gradually and naturally seeps out of its source rock and migrates elsewhere. Eventually, the oil may accumulate either by getting trapped in a permeable, porous rock called reservoir rock, or by moving up on its own to Earth's surface. (creating an oil seep)
How do the oceans play a role in climate change and global warming?
The oceans store and transport a tremendous amount of heat around the globe. Much of the heat currently absorbed by the earth is stored in its oceans. The increased heat supplies energy to spawn hurricanes of greater intensity.
How far back do glacial ice-core records date?
The oldest ice-core records come from the Antarctic and date back 800,000 years. Those from Greenland date back 160,000 years. The records from both, when compared, show similar results: warming trends, cooling trends, and correlation between historic CO2 and methane levels and global temperature.
How is hydroelectric power generated? What are some of its benefits and limitations?
The principal requirements for hydroelectric power are a large volume of water and its rapid movement: the power is generated from the energy of the flowing or falling water. Usually, this is generated by damming up a river and releasing the water slowly so that the energy generated is constant as opposed to seasonal. Benefits- hydropower is a clean energy source, and a further benefit is that water used is not consumed- it is just "passing through" and then returns to its source. Multiple plants can be created just for one stream; and the power is renewable as long as the streams continue to flow. Limitations of hydroelectric power: Loss of ecological habitats- both upstream (gets flooded by the dam) and downstream (loses its water source, sediment supply, and reduction in periodic floods) Silting up of reservoirs- because only water passes through the dam, the regions downstream lose their sediment supply, which leads to erosion of the downstream sedimentary structures; while the region above the dam accumulates an excess sediment supply, which can choke up the streambed. Dam failure- some dams fail to poor construction, age of the dam, or the underlying geology
What is the minimum estimated burial time needed to produce oil and for gas to form?
The process of how organic material is converted into oil is not well understood and thought to take at least 1-2 million years.
How are 18O / 16O levels used as a proxy for measuring ancient climates? Why are they found in ice cores, and how do their levels change with global warming and cooling trends?
The relative abundances of 18O / 16O found in sea water, fossil shells, and in bubbles in glacial ice are used to make predictions of past global temperatures. Briefly, because O16 is lighter than O18, O16 will evaporate from an equatorial sea more readily than O18. Conversely, O18 will precipitate out more readily than O16 when returning as rain or snow back to earth. As air moves from the Equator to the poles (warm to cold), O16 precipitates out as rain. That O16 is deposited as rain or snow over the poles, and depending on the climate, can get incorporated into glacial ice. Because O18 does not make it to the poles as much, glacial ice has more O16 than O18. Conversely, sea water will have more O18 than O16. During the ice ages, when cooler temperatures were found by the equator, we would expect to see glacial ice with a higher O16 content, and ocean water with a higher O18 concentration. During times of global warming, we would expect to see the reverse. To summarize, the 18O / 16O ratio would be larger during ice ages because ocean water would be enriched in O18 and O16 would be trapped in ice caps. Microorganisms making their shells during this cooler period would have higher concentrations of O18 in them.
What is the lateral moraine?
The side edge of the glacier.
Why are there deserts at 30 degrees north and south latitude? What is a rain shadow and where/how do they form?
The sinking cool air at 30 degree north and south latitude results in desert environments due to cooler air warming as it reaches the surface, taking with it much of the moisture, causing rapid evaporation. Mountain ranges that lie in the path of air currents may push the air in higher altitudes as the air rises over the range, causing the air to cool and for it to lose its moisture (which precipitates out as rain). As a result, one side of the mountain range is wet, but the opposite side is dry, forming a rain shadow. Rain shadows are formed by the Sierra Nevada mountains and the cascade range.
What are two of the most heavily consumed metals used in the US? From where are they mined? Of the nonmetallic metals, which are economically (or environmentally) significant?
The two most heavily consumed metals are iron and aluminum. Iron is mined principally from ancient sedimentary deposits but also from laterites and from concentration of magnetite in some igneous bodies. Aluminum is mostly mined commercially from bauxite, in which the aluminum is found as a hydroxide. Of the nonmetallic metals, sulfur negatively affects the environment but can be used for industrial purposes. Halite can be used for road salt or for table salt. Gypsum is necessary for US agriculture (fertilizer). Sand and gravel are used for construction.
How many gallons are in a barrel of oil? Roughly, what is the number of global oil reserves? Roughly, what is the number of proven US reserves? About how long would they be expected to last if no new reserves were found?
There are about 42 gallons of crude oil in a barrel of oil. About 1.65 trillion barrels remain in the global oil reserves. In the US reserves, there are about 35.8 billion barrels. The US reserve is about a 5-year supply.
What is thermohaline circulation? What does the phrase "ocean conveyor" refer to and how does it influence regional temperatures?
Thermohaline circulation- the roles of temperature and salinity in the movement of ocean currents. Temperature and salinity change the density of the water, causing the water to move accordingly. Ocean conveyor belt- global circulation of ocean waters contributes to the change. The Gulf Stream is a part of this larger belt, whereby warm surface water is transported east and north to Greenland, where it cools from contact with cold Canadian air. As the water cools, it increases in density and sinks to the bottom, a process known as downwelling. Then it flows south and east to the Pacific, where it warms up again and upwelling occurs. The hear released into the atmosphere from the Gulf Stream helps keep Northern Europe at least 10 degrees Fahrenheit warmer than it would be if this was thermohaline.
How do greenhouse gasses contribute to global warming?
These gasses trap heat and warm the lower atmosphere, similar to the effect of the trapping of solar heat by a greenhouse.
What influences the temperature of the earth?
To balance the energy arriving in from the sun, the earth radiates, on average, the same amount of energy back out into space. The heat is emitted by the Earth as longwave infrared radiation. Given the size of the earth relative to that of the Sun, the earth emits enough heat to warm it up to -17 degrees Celsius.
What are some of the environmental conditions needed to create fossil fuels? Under what temperatures do fossils fuels ideally form?
To create a large deposit of fossil fuel, two requirements need to be met: A large supply of organic matter (rich in carbon and hydrogen) Rapid burial, to protect it from being broken down by oxygen in the atmosphere. By removing the material from the atmosphere, it is prevented from undergoing aerobic decomposition, which would destroy it. Instead, burial of the material allows it to undergo anaerobic decomposition, which preserves and concentrates it. A large supply of organic material gets deposited: In the ocean- when microscopic organisms like plankton die, they sink down to the ocean floor. Those deposits accumulate on the ocean floor over time. On land- swaps and lakes often serve as future sites for coal and oil deposits. Temperatures post-burial are thought to be relatively low, within the range of 50-100 degrees celsius. And sometimes higher to produce methane gas.
In what type of geological environments does oil get trapped? Which of these reflects the vast oil reserves found in Saudi Arabia?
Types of petroleum traps- simple fold trap, petroleum accumulated in a fossilized ancient coral reef, a fault trap, petroleum tapped against an impermeable salt dome, which has risen up from a buried evaporite deposit. An impermeable layer that oil can get trapped under is called cap rock. Saudi Arabian oil fields are an example of this.
How is plutonium-239 created? What is its role in a nuclear reaction?
U-238 can be induced to capture a free neutron, and turn into plutonium-239, which is fissionable and can be used to further power a nuclear reactor.
In general, what happens in a nuclear fission chain reaction?
Uranium-235 is induced to undergo fission by firing a free neutron into the nucleus of one U-235 atom. When the neutron strikes the U-235 nucleus, the uranium nucleus splits into two smaller nuclei and produced subatomic particles, free neutrons, and heat. Each released neutron then strikes another U-235 atom, releasing more neutrons, and so on beginning a nuclear chain reaction. Fission-powered nuclear reactors rely on controlled chain reactions for their energy supply. The energy released heats cooling water that circulates through the reactor's core. That heat is converted into steam, which runs turbines to produce electricity.
What is the middle moraine?
Where two valley glaciers merge, the debris in the two lateral moraines merge to become a medial moraine, which is often seen as a stripe running down the composite glacier.
How is wind energy generated? What are some of its benefits and limitations?
Wind turbines use blades to collect the wind's kinetic energy. Wind flows over the blades creating lift, which causes the blades to turn. The blades are connected to a drive shaft that turns an electric generator, which produces electricity. Benefits- wind power is renewable, but it is also variable. A benefit is that when wind speeds increase, power output increases. Wind-power capacity has been rising in the US. Limitations- the windiest spots in the US are far removed from the areas that could make the best use of wind-generated electricity. We are strongly limited by the inefficiencies of long-distance electrical transmission. Another limiting factor is that strong winds do not always blow. As with solar energy, no effective way exists to store wind energy for future use. So despite the prevalence of wind, there is no way to harness it effectively.
Can solar electricity be made without photovoltaic cells? How?
Yes it can- by using arrays of parabolic mirrors, which can focus sunlight from a broader area onto a small expanse of solar cells. Alternatively, the solar energy can simply be concentrated to heat water or another medium to run turbines to generate electricity, just as other fuels heat water to make steam for power generation.
