Test III Review Questions

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Hillsborough Community College *

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2010

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Geology

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Apr 3, 2024

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1. What are the products of volcanic eruptions? Ash, falls, pyroclastics flows, lava flow, and gas emission. 2. How do columnar joints form? By cooling lava flows, ash-flow tuffs, and other bodies of magma or lava. 3. Describe a pyroclastic flow. a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases . What type of rock is formed by lithification of pyroclastic flows? Lithified ash is called “tuff.” 4. Name and describe the different type of pyroclcastics. Pyroclasts are classified by size and shape as follows: Ash: A pyroclast grain with a diameter less than 2 mm (0.08 inches). Lapilli: A pyroclast with a mean diameter between 2 and 64 mm (0.08 and 2.5 inches). Block: A pyroclast with a diameter greater than 64 mm (2.5 inches) and that has an angular shape. 5. Name the gases commonly given off by a volcano. water vapor (H 2 O), followed by carbon dioxide (CO 2 ), and sulfur dioxide (SO 2 ). 6. Where are pillow lavas found ? wherever lava is extruded underwater, such as along marine hotspot volcano chains and the constructive plate boundaries of mid-ocean ridges. 7. Contrast the difference in felsic and mafic lavas. Mafic lava produces basalt and is low in silica content and high in dark and iron-rich mafic minerals like pyroxene. On the other hand, felsic magma is higher in silica and produces rhyolite rock. Felsic magma contains light-colored minerals like orthoclase. Felsic rocks are lighter in color as compared to mafic rocks. 8. Be able to name and define the features of volcanoes including magma chambers, fissures, vents, and craters. magma chamber - this is where the molten rock is stored beneath the ground. main vent - this is the channel through which magma travels to reach the Earth’s surface. secondary vent - some magma may escape through the side of the volcano, particularly if the main vent becomes blocked. Crater - is an approximately circular depression in the ground caused by volcanic activity. Fissure - also known as a volcanic fissure , eruption fissure, or simply a fissure, is a linear volcanic vent through which lava erupts. 9. What is a caldera? a large volcanic crater, especially one formed by a major eruption leading to the collapse of the mouth of the volcano. 10. What is a flank eruption? is a volcanic eruption that occurs on the flanks of a volcano, instead of at its summit . 11. Describe how volcanoes differ in size and shape. Volcanoes come in different sizes and shapes. The overall size of a volcano is determined by the total volume of lava that has erupted. The shape of a volcano is largely determined by the type of lava that has erupted, and importantly, its viscosity. Olga Vega
12. Explain the different eruptive styles of volcanoes. eruptions can be explosive , sending ash, gas, and lava high up into the atmosphere, or the magma can form lava flows, known as effusive eruptions. 13. Describe the type of eruption found in Hawaii. What are some of the unique features? Hawaiian-style eruptions are non-explosive eruptions of gusher-like lava fountains that generate red-hot lava rivers of very fluid basaltic lavas . Hawaiian eruptions are typical for shield volcanoes, where eruptions occur at the summit and at fissure vents. 14. Contrast the three types of subaerial volcanoes. There are three main types: shield volcanoes, stratovolcanoes, and cinder cones. 15. Describe the eruption of Mt. St. Helen’s . Its eruption types were Phreatic, Plinian, and Pelean. The landslide depressurized the volcano's magma system and triggered powerful explosions . Rocks, ash, volcanic gas, and steam were blasted upward and outward. 16. Where is Olympus Mons located? What type of volcano is it? Olympus Mons sits on the equatorial region of the planet Mars. It’s a shield volcano. 17. Why did Iceland form? Iceland formed by the coincidence of the spreading boundary of the North American and Eurasian plates and a hotspot or mantle plume – an upsurge of abnormally hot rock in the Earth´s mantle. As the plates moved apart, excessive eruptions of lava constructed volcanoes and filled rift valleys. 18. What are the hazards to humans from volcanoes? lava flows, pyroclastic flows, and landslides or debris avalanches . Volcanic activity also produces hazards that can affect areas far from the volcano, such as tephra or ash falls, releases of gas, and tsunamis. 19. What tools are used to monitor volcanoes? Researchers use seismic monitors to track the many small tremors that occur around a volcano and tiltmeters and strainmeters measure subtle changes in ground slope and shape at volcanoes. 20. What is the geologic setting for volcanic activity? constructive plate boundaries , destructive plate boundaries, and hot spots. 21. Be able to name and describe the motion of different types of faults. There are four types of faulting -- normal, reverse, strike-slip, and oblique . A normal fault is one in which the rocks above the fault plane, or hanging wall, move down relative to the rocks below the fault plane, or footwall. A reverse fault is one in which the hanging wall moves up relative to the footwall. 22. How does a fault exhibit stick-slip behavior? when a fault exhibits velocity-weakening behavior, meaning friction decreases with increasing velocity. 23. What is the elastic strain on a fault? When two sides of a moving fault get stuck, the movement "stretches" the earth's crust around the stuck area. This stretching is called strain. 24. What are foreshocks? Aftershocks? Foreshocks are the energy release and ground shaking before an earthquake and aftershocks are the energy release and ground shaking after an earthquake . 25. What instrument measures earthquakes? A seismograph or seismometer
26. Give the difference between epicenter and focus. The epicenter is the location on the surface of the Earth directly above where the earthquake starts. Focus (aka Hypocenter) is the location on the Earth where the earthquake starts . 27. Describe the scales used to measure earthquakes. How are they different? the moment magnitude scale, which measures magnitude (M), or size, and the Modified Mercalli scale, which measures intensity . 28. Describe the different types of seismic waves, how they move, and how they are used to interpret the earth’s interior. P waves can travel through liquid and solids and gases, while S waves only travel through solids . Scientists use this information to help them determine the structure of Earth . 29. What is fault creep? Also known as aseismic creep, is measurable surface displacement along a fault in the absence of notable earthquakes. Aseismic creep may also occur as an "after-slip" days to years after an earthquake. 30. Geographically (on a map) where do most earthquakes occur? at the circum- Pacific seismic belt found along the rim of the Pacific Ocean . 31. Geologically (plate tectonics) where do earthquakes occur? Earthquakes occur along fault lines, cracks in Earth's crust where tectonic plates meet . They occur where plates are subducting , spreading, slipping, or colliding. As the plates grind together, they get stuck, and pressure builds up. 32. What are intraplate earthquakes? Give examples. are earthquakes that occur in the interiors of the lithospheric plates. Examples of intraplate earthquakes include those in Mineral, Virginia, in 2011 (estimated magnitude 5.8), Newcastle, New South Wales in 1989, New Madrid in 1811 and 1812 (estimated magnitude as high as 8.6), the Boston (Cape Ann) earthquake of 1755 (estimated magnitude 6.0 to 6.3) 33. What are some effects of earthquakes? What are the hazards? ground shaking, soil liquefaction, landslides, fissures, avalanches, fires and tsunamis . 34. What is liquefaction? turning loosely packed, water-saturated soil to liquid How does it affect structures? Liquefied soil loses its density and ultimately the ability to support roads, buried pipes, and, of course, houses . 35. What is a tsunami? Describe the effects. Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea . Most tsunami damage and destruction are caused by flooding, wave impacts, erosion, strong currents, and floating debris 36. Contrast the differences between short-term and long-term earthquake prediction. Short- term predictions focus on immediate warnings, while long-term predictions estimate the likelihood of earthquakes occurring within several years or decades. 37. Why is geologic time important? Because portrays the history of the Earth a standard timeline is used to describe the age of rocks and fossils and the events that formed them. 38. What is deep time? geological time or cosmic time, in other words: billions of years.
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39. What were the discoveries of Steno? the Earth's crust contains a chronological history of geologic events, and that the history may be deciphered by careful study of the strata and fossils . Hutton? how soils were formed by the weathering of rocks and how layers of sediment accumulated on Earth's surface. 40. Contrast relative and numerical time. Relative Time: sequence of events without consideration of amount of time . Numerical Time: (sometimes called "absolute time"), dates or durations of events in terms of seconds, years, millions of years, etc. 41. What is uniformitarianism? the theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes. 42. What is original horizonality? Lateral continuity? Baked contacts? Inclusions? Cross-cutting relationships? How is each used in age dating? Be able to determine relative age using each. original horizonality - refers to the original rock layers that lie horizontally to each other. As scientists know that the oldest rocks formed will be on the bottom, relative dating can determine the surrounding rock ages . lateral continuity - tells us that sediment initially extends laterally in all directions and is laterally continuous when they are first laid down. Rocks that are otherwise similar but that are separated by a valley or other erosional feature can be assumed to be of the same origin and the same age. baked contact - refers to the phenomenon of magma heating the rocks it touches as it cools into igneous rock. Any rock surrounding an igneous rock that contains these heat markings must be older than igneous rock as it had to be present as the magma was cooling. inclusions - states that any rock fragments that are included in the rock must be older than the rock in which they are included. For example, a xenolith in an igneous rock or a clast in sedimentary rock must be older than the rock that includes it. Cross-cutting relationships - state that any geological feature that cuts across or disrupts another feature must be younger than the feature that is disrupted. 43. What is fossil succession? How is it used in age dating? Evolution has produced a succession of unique fossils that correlate to the units of the geologic time scale . Assemblages of fossils contained in strata are unique to the time they lived and can be used to correlate rocks of the same age across a wide geographic distribution. 44. What are the different types of unconformities? Explain how each is used in age dating. Be able to determine relative age using unconformities. Nonconformity: develops where sediments are deposited on top of an eroded surface of igneous or metamorphic rocks. Paraconformity: strata on either side of the unconformity are parallel, there is little apparent erosion. Angular unconformity: strata is deposited on tilted and eroded layers (such as at Siccar Point) 45. What is stratigraphic correlation? How is it used in age dating? Be able to determine relative age using stratigraphic correlation. is a tool for identifying strata units and
subsequent flow units and it determines the equivalence of age or stratigraphic position (position in a vertical sequence of rock layers) of strata in different areas. 46. What are geologic maps? Why are the colors important? special-purpose maps made to show various geological features and their colors are important because they delineate the distribution of various rocks (stratigraphy, lithology) and other features. 47. What is the geologic time scale? Know the major divisions. it is what divides up the history of the earth based on life forms that have existed during specific times since the creation of the planet. Its major divisions are from longest to shortest: eons, eras, periods, epochs, and ages. 48. How is radioactive decay used in age dating? By measuring the number of unstable atoms left in a rock and comparing it to the number of stable daughter atoms in the rock, scientists can estimate the amount of time that has passed since that rock formed. 49. What is a half-life? How does it determine age? is the length of time after which there is a 50% chance that an atom will have undergone nuclear decay. It determines age by multiplying the number of half-lives that have passed by the half-life decay constant of the parent atom. 50. What is dendrochronology? How is it used to determine age? the science that assigns accurate calendar dates to the yearly growth rings produced by trees and determines age by comparing the tree-ring pattern of samples with unknown dates to known samples from the same geographical area . 51. What is magnetostratigraphy? How is it used to determine age? a technique that uses the record of the polarity reversals of the Earth's magnetic field registered in sedimentary and/or volcanic rocks as a correlation and dating tool and determines age by identification in the stratigraphic record of magnetozones, which can be correlated to age equivalent. 52. What is energy? the ability to do work or produce change . What is fuel? any substance that can provide heat and produce energy when it is burned . 53. What are the five fundamental sources of energy on Earth? Solar energy from the sun, Geothermal energy from heat inside the earth, Wind energy, Biomass from plants, and Hydropower from flowing water. 54. Describe fossil fuels and give their importance to society. How do they form? What is the oil window? fossil fuels are all Hydrocarbons, they are compounds formed from only two elements, Carbon and Hydrogen. They are important because We depend on those fuels to heat our homes, run our vehicles, power industry and manufacturing, and provide us with electricity . They formed over millions of years as heat and pressure from layers of sediment changed the decayed organic remains. The oil window refers to the depth or maturity range within which a source rock generates and expels liquid petroleum . 55. What are the different types of hydrocarbons? aliphatic and aromatic.
56. How did most oil and gas form? They formed underground, over several to tens of millions of years, from prehistoric organisms decomposed by high subterranean heat and microorganisms . 57. Describe nuclear fission and its usage. In nuclear fission, atoms are split apart, which releases energy . All nuclear power plants use nuclear fission, and most nuclear power plants use uranium atoms. During nuclear fission, a neutron collides with a uranium atom and splits it, releasing a large amount of energy in the form of heat and radiation. 58. What are the different oil traps and seals? Why are those needed? 59. Which types of rock are good reservoir rocks? Jurassic limestones and sandstones Source rocks? shales or limestones (sedimentary rocks) . 60. What is permeability? a measure of the ability of a material (such as rocks) to transmit fluids . Porosity? is a measure of the void spaces in a material . 61. Do you find oil and gas in the same well? Yes, most oil wells produce at least a little gas, and vice versa. 62. Describe the techniques used in oil and gas exploration. The primary 3 are Geophysical, Remote Sensing, and Wildcatting. 63. Where are most of the world’s oil reserves? in the Middle East. Why in those areas? Because they are in the great Arabian Iranian basin. 64. Describe the use of tar sands, gas hydrates, and oil shale. Both materials can be converted into synthetic crude oil through different processes; tar sands can be refined directly into petroleum products in some cases. 65. What is coal? How did it form? coal is a fossil fuel, and it forms as the plants die, they sank to the bottom of the swamps. Over the years, thick layers of plants were covered by dirt and water. They were packed down by the weight. After a long time, the heat and pressure changed the plants into coal . 66. What gas is given off by the burning of coal? Carbon dioxide (CO 2 ) 67. Where are most of the world’s coal reserves? When and how was most deposited? Most of the world’s coal reserves are in the US and they were deposited there millions of years ago. Coal contains the energy stored by plants that lived hundreds of millions of years ago in swampy forests. Layers of dirt and rock covered the plants over millions of years. The resulting pressure and heat turned the plants into the substance we call coal . 68. How is coal extracted? In surface mining, large machines remove the topsoil and layers of rock known as overburden to expose coal seams . Mountaintop removal is a form of surface mining where the tops of mountains are removed to access coal seams. 69. What is uranium and how is it used in power generation? is the fuel most widely used by nuclear plants for nuclear fission. During nuclear fission, a neutron collides with a uranium atom and splits it, releasing a large amount of energy in the form of heat and radiation and this is how power is generated. 70. What are the challenges of a nuclear power plant? Improper storage and disposal of nuclear waste, radioactive sources like uranium, decompose into harmful
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elements, and any accidental leakage of radiation causes havoc and destruction to life and property in the vicinity of the plant. 71. What is the difference between renewable and nonrenewable energy? renewable resources can naturally replenish themselves while nonrenewable resources cannot. 72. What are biofuels? liquid fuels produced from renewable biological sources, including plants and algae . 73. Describe geothermal energy and its usage. is the heat produced deep in the Earth's core and can be harnessed for use as heat and electricity. 74. Describe hydroelectric energy and its usage. is a renewable source of energy that generates power by using a dam or diversion structure to alter the natural flow of a river or other body of water. It is used for electricity generation. 75. Describe solar energy and its usage. is a renewable, inexhaustible, and affordable form of energy . It can be used to cook food, heat water, and generate electricity. 76. What was the oil crunch? What could that mean for the future? the oil crunch was the embargo that ceased U.S. imports from participating OAPEC nations. That means a sudden rise in the price of oil that is often accompanied by decreased supply . 77. Describe some environmental issues associated with fossil fuels . Air pollution, water pollution, plastic pollution, and oil pollution.