GEOL 101 Exam
Compare and contrast Big Bang Theory & Nebular Theory. Details are important— include the evidence for each theory in your comparison.
Big Bang Theory: Universe, rapid expansion Similarities: Both involve fusion — creating elements thru nucleosynthesis Nebular Theory: Accretion-based, planets and solar systems, stars and heavy elements
Physical vs. compositional layers of the Earth.
Compositional: -Elementally different; different compositions -Different densities Crust, mantle, core Physical/Mechanical: -Changes in behavior, not composition -Changes in state ---> Plastic = lower rigidity than solid Lithosphere, Asthenosphere, Upper mantle, Lower mantle, Outer Core, Inner Core
Describe the dominant processes involved in the Hydrologic Cycle.
Condensation Transpiration Precipitation Infiltration/Percolation Surface Runoff Accumulation Evaporation
Identify & explain how (what type of medium is needed) heat is transferred via radiation, conduction, advection, & convection. How does heat flow?
Conduction -Heat is transferred through solids, without the flow of material. Convection -Heat is transferred through liquids and gases via the movement of mass. Advection -Heat is transferred via the movement of a liquid through cracks or pore spaces in a solid.
Compare and contrast continental drift and sea-floor spreading.
Continental Drift: Wegener's lines of evidence Similarities: Both hypothesis to describe tectonics plates were moving Sea-Floor Spreading: Marine Magnetic anomalies
How are rigidity and compressibility related to density?
As rigidity increases, density increases As compressibility increases, density decreases As compressibility increases, rigidity decreases
Compare & contrast asthenosphere and lithosphere (density, thickness, composition, function, state of matter):
Asthenosphere: plastic -Uppermost mantle -Base of lithosphere to ~350 km -Higher temperatures -Moderate pressure -Weak & plastic (flows slowly) ---> The lithosphere "floats" on the asthenosphere Similarities: -Mechanical layers -Both contain upper mantle -Both facilitate plate movement Lithosphere: -rigid (solid) -Consists of crust & uppermost mantle -Earth's surface to ~100-250 km -Low temperature & pressure -Strong and rigid
What are the sub-systems, "spheres" or storage reservoirs of the Earth system?
B.L.A.H. Biosphere, Lithosphere, Atmosphere, Hydrosphere
*Compare and contrast a Big Bang Nucleosynthesis and Stellar Nucleosynthesis.
BBG Nucleosynthesis: Similarities: Stellar Nucleosynthesis:
Explain how the thickness of the sediment layer on the bottom of the ocean floor varies? (Where is thickest? Thinnest?)
Better Understanding of Oceanic Crust -Layer of sediment (clay & shell) progressively thickens away from the Mid-Ocean ridge axis. -Thickest near continents. -Thinnest (or absent) at the mid-ocean ridge. -Dredged rock samples revealed the presence of only basalt & gabbro. (Uniform composition!)
What are greenhouse gases? What do they do (i.e.- how do they make our planet habitable)?
Greenhouse gases include methane, carbon dioxide, and water vapor. They trap the heat and maintain Earth's temperature. (Maintain a habitable temperature).
Why do the inner planets consist mostly of refractory materials, but the outer planets mostly of gas?
(The sun stellar winds blew away the gases on the inner planets but did not reach the outer ones).
What are feedback mechanisms? What is the relationship between sources and sinks and positive and negative feedback mechanisms?
-In a system, all parts are linked, so changes in one part can affect the processes in another. -A feedback mechanism is a part of the output of a system that is returned to its input in order to regulate further output. -Feedback mechanisms act to either enhance or resist a change within a system. ---> Positive Feedback Mechanism = Enhance the change (Sources) ---> Negative Feedback Mechanism = Resist the change (Sinks)
What is the criteria of a planet? Why isn't Pluto a planet?
-It is in orbit around the Sun. -It has sufficient mass to assume hydrostatic equilibrium (a nearly round shape). -It has "cleared the neighborhood" around its orbit. Pluto is not a planet because it has not cleared its orbit of other objects.
Explain why the Earth is not a perfect sphere?
-Outward "push" from rotation -Rotation about the axis causes: Equatorial Bulge Polar Flattening ^ Happens because we're spinning Molten state spinning: material pushed to center region; low internal strength). -WHY does this happen? Centrifugal Forces (This deformation results from a low internal strength).
Be able to identify & explain how technology advancements led to Henry Hess's Sea-Floor Spreading Hypothesis. - Be able to explain the importance of the discovery of paleomagnetism. - Be able to explain the importance of apparent polar wonder. - Be able to explain the importance of unequal heat distribution in the ocean. -Be able to explain the importance of the sediment distribution [thinnest at MORs and thickest at the edges ( continental coastlines)]
-Paleomagnetism: Could calculate spreading of sea-floor with marine magnetic anomalies -Apparent polar wander: Continents, not poles, are moving -More heat at MORs --New crust moves away from ridges, gathering sediment.
What is a seismic discontinuity and why are they important to distinguishing the layers of the Earth?
-Seismic discontinuities (when density decreases and waves slow down) result from regions that have different compositions, temperatures, or fluid contents. Allows us to learn about the dimensions and properties about deep Earth.
Describe the hypothesis of sea-floor spreading. How does crust form along a mid- ocean ridge?
-The asthenosphere beneath diverging plates rises and melts. -A magma chamber forms beneath the ridge axis. -Magma rises to the surface and erupts via submarine volcanoes. -Newly-formed crust is moved laterally away from the ridge. Instantly provided a mechanism for continental drift. -Continents move apart as sea-floor spreading occurs. -Continents move together as sea-floor sinks into mantle.
Define magnetic declination. What causes it?
-The difference between geographic N and magnetic N is called declination. It depends on: -Absolute position of the two poles: ---> Geographic north ---> Magnetic north -Longitude
Why is this information helpful to understanding the internal structure of the Earth?
-The difference in the wave properties and the time it takes the wave to travel through a material can tell us a great deal about the type of material that is present. -Anomalies (when density decreases and waves slow down) result from regions that have different compositions, temperatures, or fluid contents. Allows us to learn about the dimensions and properties about deep Earth. For example: -P-wave shadow zone -S-waves unable to move through liquid (Can't move through mantle)
What is paleomagnetism? What causes the Earth's magnetic field? What does it mean when we say that Earth's magnetic field behaves like a dipole?
-The study of fossil magnetism is called paleomagnetism. -Iron (Fe) minerals in rock preserve information about the magnetic field at the time the rocks formed. -Layered basalts record magnetic changes over time. -Inclination and declination indicated change in position.
What is a geologic agent?
Anything that changes the geological makeup & topography of Earth.
Chronologically rank the following steps in the formation of our solar system according to the Nebular Theory.
1) A nebula forms from hydrogen and helium left over from the Big Bang, as well as from heavier elements that were produced by fusion reactions in star or during explosions of stars 2) Gravity pulls dust and gas inward to form an accretionary disk. Eventually, a glowing ball, the proto-Sun, forms at the center of the disk. 3) "Dust" and refractory materials concentrate in the inner rings, while "ice" and volatile materials concentrate in the outer rings. Eventually, the dense ball of gas at the center of the disc becomes hot enough for fusion reactions to begin. When it ignites, it becomes the Sun. 4) Dust and ice particles collide and stick together, forming planetesimals. 5) Planetesimals grow by continuous collisions. Gradually, an irregularly-shaped proto-Earth develops. The interior heats up and becomes soft. 6) Gravity reshapes the proto-Earth into a sphere. The interior of the Earth differentiates into a core and mantle. EARTH/MOON FORMATION: 7) Soon after Earth forms, a protoplanet collides with it, blasting debris that forms a ring around Earth. 8) The Moon forms from the ring of debris. 9) The atmosphere develops from volcanic gases. When the Earth becomes cool enough, moisture condenses and rains to produce oceans. Some gases may be added by passing comets.
Greenhouse Effect:
1) Solar radiation passes thru the atmosphere 2) Some radiation is reflected by the atmosphere and Earth's surface 3) Solar energy is absorbed by the Earth's surface and warms it --> converted into heat, causing the emission of infrared radiation back to the atmosphere 5) Some of the infrared radiation is absorbed and re-emitted by the greenhouse gas molecules. The direct effect is the warming of Earth's surface and the troposphere. Surface gains more heat and infrared radiation is emitted again. 6) Some of the infrared radiation passes through the atmosphere and is lost in space.
The Montreal Protocol is celebrating its 25th anniversary this year. While many view it as a huge success others say that it is failure, because of the trade-offs that were made. What was the Montreal Protocol? Why is it important? Identify the dominant technological "trade-offs" that was made as a result of the MP?
1st international, environmental treaty that brought "politics and science came together." 43 nations met in Montreal to discuss rapidly growing hole in ozone layer. First international environment treaty. Called for a phasing out of the end of the production and use of CFCs. It's considered to be a failure because, since it emphasized a SLOW phasing out of CFCs to reach compromise, not much progress has been made in 27 years.
What is the Geothermal Gradient? Describe how it changes with depth?
Although temperature increases with depth, the RATE at which temperature increases DECREASES. Temperature increase is faster at crust/just above mantle.
What is anthropogenic climate change? What the effects of it? How do humans generate excess greenhouse gases?
Anthropogenic climate change is climate change influenced by human activity. -Carbon dioxide: Burning of fossil fuels such as coal, oil and gas; deforestation -Methane: agriculture (livestock), fossil fuel extraction, and the decay of organic waste in landfill sites.
Make sure you understand convection cells—what is the role of density?
Convection cells: -Most of the mantle is solid rock -Convection is DENSITY-driven and INFLUENCED by heat -As temperature increases, surface area expands -As surface area increases, density decreases -With less density, it rises -Magma cools, and surface area decreases -Density then increases; then rocks go back down (Temperature drives changes in density; density causes the churning)
Explain how and why the velocity of seismic waves changes inside the Earth?
Density increases with depth; seismic wave velocity increases with density.
Describe how each of the following change as you move deeper into the Earth. Density: Temperature: Pressure:
Density: Increases Temperature: Increases Pressure: Increases
What is the red shift? How is it related to the Doppler Effect?
Doppler Effect: Describes the change in frequency of a wave for an observer moving relative to the source of the waves. Sound waves compress or relax with relative motion. Compressed: shorter wavelength; higher frequency. Relaxed: longer wavelength; lower frequency. (^^Red shift!) (ex. A stopped train sounds different than a moving train. As the train approaches, a person hears a higher pitch. As the train passes, the pitch drops (higher to lower). As the train recedes, a person hears a lower pitch). Moving light waves reveal the Doppler effect; Light moving away from an observer expands (red). • Edwin P. Hubble observed that all nearby galaxies displayed a red shift, which he interpreted to mean that the universe was expanding!
What is the significance of the moon's synchronized rotation and revolution?
Earth only sees one side of the moon.
Identify three natural geologic agents.
Earthquakes Tsunamis Volcanic eruptions
Identify if the following events are GEOGENIC or ANTHROPOGENIC?
Fossil fuel combustion: Anthropogenic Tsunami: Geogenic Earthquakes: Geogenic
Compare and contrast a geocentric and heliocentric model of the Universe.
Geocentric: Earth is at the center Similarities: Heliocentric: Sun is at the center
Humans are geologic agents, impacting the Earth's land, water (oceans), and atmosphere. Identify at least two specific examples of how humans have negatively impacted the following: (B) Oceans
Global Commercial Fishing -Overfishing: loss of a food resource -Loss of biodiversity; destroys seafloor habitat; impacts balance of marine communities -Today's fisheries are not sustainable -Bycatch & bottom trawling Pollution -Loss of ecosystems -Loss of biodiversity -Loss of resources -Direct pollution: ex. "dirty water" -Indirect pollution: Rise in ocean water surface temperature
Geoscientists quantify change in the Earth system according to Rate, Agency, Frequency, and Time scale (RAFT). Identify examples of both GRADUAL and CATASTROPHIC change.
Gradual: Movement of tectonic plates, formation of supercontinents Catastrophic: Mass extinctions (brought on by voluminous volcanic eruptions, impact of a comet or asteroid with Earth — eject debris into atmosphere to block sunlight)
Be able to define and explain the importance of the Sea-Floor Spreading Hypothesis proposed by Hess and identify the lines of evidence that he provided. - Use a paleomagnetic record and determine the location of the oldest & youngest crust. - Identify what scientists learned from paleomagnetic reversal chronology. - Explain the importance of the correlation between marine anomalies and magnetic reversals
Hess proposes Sea Floor Spreading -In 1960, Harry Hess published his "Essay in Geopoetry." -Sediment thickens away from ridges -Earthquakes at mid-ocean ridges indicate cracking. ---> Cracked crusts splits apart. ---> High heat flow from molten rock rises into the cracked crust. -New ocean floor forming at mid-ocean ridges. ---> Rising magma is less dense; becomes buoyant and rises up. ---> Cools and becomes crust; becomes more dense. Hess called his theory "sea floor spreading." -Upwelling magma erupts at mid-ocean ridges -New crust moves away from ridges, gathering sediment. -At trenches, the sea-floor sinks back into the mantle. Instantly provided a mechanism for continental drift. -Continents move apart as sea-floor spreading occurs. -Continents move together as sea-floor sinks into mantle. ---> Subduction = goes back into the mantle and is re-melted. Evidence of Sea-Floor Spreading -Marine Magnetic Anomalies ---> Magnetic Anomaly = Refers to the difference between the expected strength of the Earth's main field at a specific location and the actual measured strength of the magnetic field at the location. -Magnetism in sea-floor rocks varies farther from MOR (mid-ocean ridge). ---> Stripes of positive (stronger) and negative (Weaker) magnetic intensity ---> Recorded in sea-floor basalts. -Earth's current magnetic field (strength and direction) + Remanent magnetic field strength and direction = Anomalously high magnetic field measurement -Earth's current magnetic field + Remanent magnetic field strength (reversed polarity) = Anomalously low magnetic field -Paleomagnetic Reversals ---> Layered lava flows reveal reversals in magnetic polarity. ---> The magnetic field sometimes "flips;" we don't know why. ---> A reversed N magnetic pole is near the S geographic pole. ---> Reversals are geologically rapid, expressed worldwide ---> Can be used as time markers ---> Paleomagnetic Reversals + Marine Magnetic Anomalies Polarity reversals explain magnetic anomaly stripes Positive anomaly - sea floor rock normal polarity Negative anomaly - sea-floor rock reversed polarity Magnetic anomalies are symmetric across the MOR (mid-ocean ridge). Paleomagnetic-Reversal Chronology -The development of radiometric dating techniques allowed geologists to determine WHEN the magnetic field of the Earth reversed. ---> Limited to dating reversals that occurred in the past 4.5 million years. ---> What causes reversals? Are reversals instantaneous? (unknown) ---> Correlation between marine anomalies and magnetic reversals. -Relationship between anomaly-stripe width and polarity-chron duration allowed geologists to determine the velocity (Rate) of sea-floor spreading. ---> Velocity = Distance/Time ---> V = 45km / 4,500,000 years = 4,500,000 cm / 4,500,000 years = 1cm/yr
How is seismic wave velocity impacted by changes in density?
Higher density, atoms tightly packed together- velocity increases Lower density, atoms more spread out- velocity decreases (Wave has to trudge through)
*What is the importance of the expanding Universe Theory?
Hubble's Discovery: -Edwin Hubble's observations of remote galaxies, and the redshift of their spectral lines (1924). -Hubble noticed that the further away the galaxy, the greater the redshift of its spectral lines. -This relationship is called Hubble's Law.
Why are humans the dominate geologic agent shaping our planet today?
Humans are the dominate geological agent because we impact and influence geology through (the large amount of our) human activity, and we operate in large numbers.
How are rigidity and compressibility influenced by changes in pressure and temperature conditions inside of the Earth?
Increase in temperature = decrease in rigidity, increase in compressibility -Less resistance to flow [means it will flow] Increase in pressure = increase in rigidity, decrease in compressibility -More resistant to flow [means it will not flow]
How is the initial mass of a star related to its life cycle (and the elements that it will go on to create via fusion during its lifetime?)
Initial mass is how much material is accreted when it ignites (determine whether it supernovas or will just be a red giant). -Initial mass determines its life cycle. High mass star that's going to supergiant and then supernova- it's going to burn faster. The more atoms present, the higher the mass, the faster the reactions are going to happen- it's not going to last as long. First generation star- not a lot of heavier elements During stars' life cycle, they are creating elements Next generation- going to have more heavy elements (Think of wealth that we pass on to generations).
What criteria are used to classify a system as closed, isolated, or open?
Isolated - no matter nor energy exchanged Closed - no matter, only energy exchanged Open - both matter and energy exchanged Earth is an open system; however, closed is a good approximation for most purposes because we're not frequently exchanging matter with space.
Be able to distinguish among isolated, closed, & open systems. - Which type of system is Earth?
Isolated - no matter nor energy exchanged Closed - no matter, only energy exchanged Open - both matter and energy exchanged Earth is an open system; however, closed is a good approximation for most purposes. WHY? Despite its name, a closed system permits the exchange of energy with the environment but does not allow matter to pass back and forth between the external environment and the system. Thus, Earth absorbs electromagnetic energy, radiated from the Sun, yet very little matter enters or departs Earth's system. Note that Earth is an approximation of a closed system: actually, some matter does pass from space into the atmosphere and vice versa. The planet loses traces of hydrogen in the extremities of its upper atmosphere, while meteorites and other forms of matter from space may reach Earth's surface.
What is prospect theory? How does it relate to/help explain why we haven't solved or mitigated the anthropogenic climate change problem yet?
Kahneman & Tversky - Prospect theory -Describes decisions between alternatives that involve risk, where the probabilities are known -Models real-life choice, rather than optimal decisions. -Early 19th Century MUD Problem Why haven't we fixed climate change? It's not killing us yet, so we're not throwing money at it. Risk- only a CHANCE (ex. flood insurance - only a CHANCE of a flood).
Be able to identify the location and the importance of the Kuiper Belt and Oort Cloud.
Kuiper Belt- towards the end of our solar system, where we find a lot of dwarf planets Oort Cloud- 3-dimensional area circling our solar system; birthplace of comets
Compare and contrast the growth rates of developed and less developed countries.
Less developed: High population growth (some are still farming, want to have larger farms + issue of access to contraceptives) Low GDP Low life expectancy (Less) education -see increase in life expectancy and fall in child mortality rates as country moves closer to being developed Increased quality in medicine, sanitation, and food supply; Birth rates start to remain constant, leading to a population boom Developed: Low population growth High GDP High life expectancy Education
What is a light year? What is an AU? Which one is a larger unit of length measurement?
Light year: The distance light travels in one Earth year AU: Astronomical Unit. 1 AU = average distance between the Earth and the Sun Light year is the larger unit of length measurement.
Carbon is an important biogeochemical cycle that connects all the Earth's subsystems. Identify a PROCESS that moves Carbon through the reservoirs specified below. Please be as specific as possible and use scientific terms. *If we are interested in the ATMOSPHERE, which of the processes identified would be considered SOURCES?
Lithosphere to Atmosphere: Volcanic eruption, cement manufacturing, Fossil Fuel Combustion Atmosphere to Biosphere: Photosynthesis Lithosphere to Hydrosphere: sea-floor spreading, magma eruptions Biosphere to Atmosphere: Respiration, Deforestation (biomass burning), decay of organic matter Atmosphere to Lithosphere: Chemical Weathering of Rocks Hydrosphere to Atmosphere: Diffusion (Loss of CO2 from surface water) Atmosphere to Hydrosphere: Carbon Dioxide dissolves into surface water SOURCES in regards to ATMOSPHERE: Volcanic eruption (lithosphere to atmosphere); Decay or organic mater (biosphere to atmosphere)
Describe the pattern of marine magnetic anomalies across a mid- ocean ridge. How is this pattern explained?
Magnetism in sea-floor rocks varies farther from MOR (mid-ocean ridge). -Stripes of positive (stronger) and negative (Weaker) magnetic intensity -Recorded in sea-floor basalts. Polarity reversals explain magnetic anomaly stripes -Positive anomaly - sea floor rock normal polarity -Negative anomaly - sea-floor rock reversed polarity -Magnetic anomalies are symmetric across the MOR (mid-ocean ridge). Layered lava flows reveal reversals in magnetic polarity. -The magnetic field sometimes "flips;" we don't know why.
Be able to identify the major steps in the Nebular Theory (formation of our solar system). -What characteristics of our solar system led scientists to propose the Nebular Theory? -What caused the accretion of the planets? (Hint: What controls gravitational attraction?)
Mass in nebulae not equally distributed. -An initially more massive region began to pull in gas. • This region gained mass and density. • Mass compacted into a smaller region and began to rotate. • Rotation rate increased, developing a disk shape. -The protostar continued to grow. • Pulling in more mass and creating a denser core. • Temperatures soared to 10 million degrees. • At these temps, hydrogen nuclei fused to create helium. • With the start of nuclear fusion, the protostar "ignites." Accretionary Disk to Proto-Sun -Eventually, the dense ball of gas at the center (Proto-Sun), becomes hot enough for fusion reactions to begin. It ignited, forming the sun. Accretionary Disk to Planetesimals -Dust and ice particles collide and stick together, forming larger particles, called planetesimals. -What held the planetesimals together? Chemical bonds: Electromagnetic , The Strong Force, The Weak Force, Gravitational forces From Planetesimals to Protoplanets -Gravitational attraction between the planetesimals caused them to collide and coalesce into larger objects called protoplanets. -The materials from which the terrestrial (inner planets) formed was rich in substances with high condensation temperatures.
What is the difference between a meteor and a meteorite? Why are meteorites important to establishing the age of the Earth?
Meteoroid - A small particle from an asteroid or comet orbiting the Sun. Meteor - A meteoroid that is observed as it burns up in the Earth's atmosphere - a "shooting star." Meteorite - A meteoroid that survives its passage through the Earth's atmosphere and impacts the Earth's surface. Meteorites are important to establishing the age of Earth because they were formed around the same time as Earth and thus iron meteorites are similar in composition to Earth's core. The average composition of all meteorites reflects the average composition of Earth.
What did scientists learn from the paleomagnetic reversal chronology? (How old is the oldest oceanic crust?)
Mid-ocean ridges are symmetrical Paleomagnetic reversals- starts with marine magnetic anomaly Took a boat with magnetometer, towed from ridge axis, determined positive and negative anomalies based off of what magnetic strength was; calculate magnetic strength of Earth based off its mass. Magnetometer picking up anything that's not normal. We learned, after getting marine magnetic anomaly data, On land, geologists noticed volcanoes were layered as well. (Pattern of normal-reverse-normal). By this time we knew Earth had paleomagnetism and we knew how to radiometrically date. Dated the rocks, came up with paleomagnetic reversal chronology. Last 4.5 million years (relatively recent). Used the rocks from the terrestrial volcano. (Rocks show magnetic alignment of magnetic minerals. Still don't know mechanism that's causing it or how fast it reverses- whether it's instant or gradual). Mid-ocean ridge: newest crust at mid-ocean ridge. Can now age-date the entire ocean floor based off age-date chronology. Create map of ocean floor that was age-dated. Can now get a distance- For example, 100km in 700,000. Distance divided by time - gives us spreading rate. Allows us to calculate sea-floor spreading rates.
How is the angle of refraction influenced by the density of the layer it is entering?
More dense, atoms tightly packed together, velocity increases Bends TOWARD boundary; smaller angle of refraction Less dense- velocity decreases; takes longer to get to a seismic station (will bend and get there eventually) Bends AWAY from boundary; larger angle of refraction
Be able to identify the importance of stellar nucleosynthesis in the Nebular Theory. - What controls the life cycle of star? - How does the ratio of light to heavy elements change from a 1st generation star to a 3rd generation star?
Nucleosynthesis -Big Bang nucleosynthesis formed the lightest elements; Atomic #s 1, 2, 3, 4, and 5 (H, He, Li, Be, B). -Heavier elements are from stellar nucleosynthesis; Atomic #s 6-26 (C to Fe). -Elements with atomic #s > 26 form during supernovae (large first and second gen stars). -First generation stars left a legacy of heavier elements. -Second generation stars repeated heavy element genesis. -Succeeding generations contain more heavy elements. MASS controls the life cycle of a star! Younger stars have heavier elements because the heavy elements were made in previous generations of stars.
Compare & contrast oceanic crust and continental crust (density, thickness, composition, function, state of matter):
Oceanic Crust: -Underlies ocean -7-10km thick -Denser than continental (Avg. Density = 3.0 g/cm_ -Subducts under continental crust -Basalt & Gabbro (Mafic rocks; Uniform/homogenous composition) -Oldest is about 200 million years; eventually subducts under continental) Similarities: -Influenced by tectonic plates -Less dense than mantle -Both contain mafic, intrusive igneous rock -Compositional layer of Earth -Provides minerals essential for life Continental Crust: -Underlies continents -30-60km thick (much thicker than oceanic) -Widely varied in composition -Less dense than oceanic crust - "floats" above it (Avg. Density = 2.7 g/cm) -Sediment & Granite( Felsic to Intermediate rocks; A widely varied composition! -Crustal stretching can thin the crust. -Mountain building can thicken the crust. -Older than oceanic -Soil - contains nutrients to support life
Compare & contrast outer core and inner core (density, thickness, composition, function, state of matter):
Outer Core: -Liquid - (temperate wins, then lean toward liquid or plastic from solid; increase in temp = decrease in rigidity, increase in compressibility) o Base of lower mantle to ~5155km o High temperatures & high pressure o Liquid o Function: influences Earth's magnetic field Similarities: -Both contain the core - iron and nickel alloys -Compositionally, they are exactly the same -Mechanical layers Inner Core: -Solid - (pressure wins, then lean toward plastic/solid from liquid; increase in pressure = increase in rigidity, decrease in compressibility) o Base of Outer core to ~6371km o Highest temps and pressures o Solid o Function: helps maintain Earth's shape
Humans are geologic agents, impacting the Earth's land, water (oceans), and atmosphere. Identify at least two specific examples of how humans have negatively impacted the following: (C) Atmosphere
Ozone Depletion -Cause: Release of CFCs (aerosols, refrigerants, solvents), HCFCs, Halons -CFCs released; CFCS rise into ozone layer -UV released Cl from CFCs -Cl destroys Ozone -Depleted ozone --> more UV radiation --> skin cancer Anthropogenic Climate Change -Shift in the climatic belts on our planet -Stronger, more frequent storms -Global rise in sea level -Increased frequency of wildfires -Leads to acceleration of the Greenhouse Effect
What is ozone? What is the difference between "good" and "bad" ozone? What is the significance of polar stratospheric clouds? What causes the ozone layer to thin?
Ozone protects the Earth from exposure to harmful UV radiation. (UV radiation strikes an oxygen molecule; oxygen molecule splits into two oxygen atoms; oxygen atoms collide with oxygen molecules; ozone is formed). Polar Stratospheric Clouds: -They are implicated in the formation of ozone holes. The effects on ozone depletion arise because they support chemical reactions that produce active chlorine which catalyzes ozone destruction, and also because they remove gaseous nitric acid, perturbing nitrogen and chlorine cycles in a way which increases ozone destruction. -(Type I clouds are now known as sites of harmful destruction of stratospheric ozone over the Antarctic and Arctic. Their surfaces act as catalysts which convert more benign forms of man-made chlorine into active free radicals (for example ClO, chlorine monoxide). During the return of Spring sunlight these radicals destroy many ozone molecules in a series of chain reactions. Cloud formation is doubly harmful because it also removes gaseous nitric acid from the stratosphere which would otherwise combine with ClO to form less reactive forms of chlorine).
Compare and contrast P-wave and S-waves.
P-waves: -Fast-moving body waves compress and expand -Longitudinal waves, so the displacement of the medium is parallel to the propagation of the wave -Travel through both solids and liquids. -The velocity of the P-wave depends on how easily the material can be compressed (the incompressibility), how rigid the material is (rigidity), and the density of the material. Similarities: Body waves S-waves: -S-waves travel through material by shearing it or changing its shape in the direction perpendicular to the direction of travel (transverse). -Travel slower than P-waves. -Only travel through solid rock; liquid cannot be sheared. -Shake the Earth's surface from side to side.
What was the name of the supercontinent that Wegener proposed?
Pangaea
Processes which remove Carbon Dioxide from the atmosphere:
Photosynthesis Carbon Acid Synthesis Carbonate Rock Weathering Silica Rock Weathering Diffusion into surface water
Compare and contrast Physical and Biogeochemical cycles. Provide at least two examples of each.
Physical: Rock Cycle, Sea-Floor Rising Similarities: Biogeochemical: Hydrologic Cycle, Carbon Cycle
What is the Impact Theory and the evidence that is used to support it?
Planet-sized body crashed into the Earth. Debris from the impact made the moon. Properties to be Explained: -Earth has an iron core; moon rocks do not have iron (did not come directly from Earth) -Earth's average density is 5.5 grams/cm; the moon's is 3.3. grams/cm -Earth has a specific isotope of oxygen; moon has the same unique isotope of oxygen
*How do apparent polar- wander paths show that the continents, rather than the poles, have moved?
Polar wandering paths were initially misinterpreted: -The signature of a wandering pole on a fixed continent. Each continent had a separate polar wandering path, which is now understood to represent that: -The location of the magnetic pole is fixed. -The continents themselves have moved.
What are the FIVE lines of evidence that Wegener used to support CDH?
Puzzle-like fit between eastern coast of South America and the western coast of Africa. Glacial Evidence -Evidence of Late Paleozoic glaciers found on five continents. -Some of this evidence is now far from the poles. -These glaciers could not be explained unless the continents had moved. Paleoclimatic Evidence -Placing Pangea over the Late Paleozoic South Pole: -Wegener predicted rocks defining Pangea climate belts. ---> Tropical coals ---> Tropical reefs ---> Subtropical deserts ---> Subtropical evaporites Fossil Evidence -Identical fossils found on widely separated land masses. -Mesosaurus - a freshwater reptile (Fossils found on both South America and Africa; an ocean currently separates the two continents). -Related to alligator, which lives in freshwater; could not swim across a saltwater ocean -The continents were once joined together. -Glossopteris - a subpolar plant with heavy seeds. (Found on all of the southern continents. "Wind" cannot carry seeds across India, Antarctica, and Australia). Matching Geologic Units -Distinctive rock assemblages and mountain belts match across the Atlantic.
Explain the difference between seismic wave reflection and refraction.
Refraction: wave bends upon entering boundary Reflection: wave bounces back
Explain the importance of the correlation between marine anomalies and magnetic reversals.
Relationship between anomaly-stripe width and polarity-chron duration allowed geologists to determine the velocity (Rate) of sea-floor spreading. -Velocity = Distance/Time -V = 45km / 4,500,000 years = 4,500,000 cm / 4,500,000 years = 1cm/yr
Processes which add Carbon Dioxide into the atmosphere:
Respiration / Combustion (Burning) / Oxidation; Decay of Organic Matter Carbonate Metamorphism Burning of fossil fuels Volcanic Eruptions - molten rock flowing to the surface
What is the difference between a rotation and a revolution of the Earth?
Rotation is when Earth turns all the way around or spins on its axis one time (1 day). The axis of rotation is an imaginary line going from the north pole to the south pole. When Earth travels once around the Sun, this is considered a revolution (1 year).
How did the seafloor- spreading hypothesis explain variations in ocean floor heat flow?
Scientists discovered that heat flow was not uniform in the ocean. -Increased Heat = close proximity to mid-ocean ridge -Decreased Heat = increasing distance from mid-ocean ridge
How was the advent of sonar important to the advancement ocean floor bathymetry mapping? Identify some of the key features that now needed to be explained.
Sea-Floor Bathymetry -Before WWII, we knew little about the sea floor. -Echo-sounding (sonar) allowed rapid sea-floor mapping. -Sea-floor maps created by ships crossing the oceans. -Bathymetric maps are now produced using satellite data. Oceanographers were surprised to discover that: -A mid-ocean range runs through every ocean. -Deep-ocean trenches occur near volcanic island chains. -Submarine volcanoes poke up from the ocean floor. -Huge fracture zones segment the mid-ocean ridge. ^^ (These observations are all explained by plate tectonics.) Sonar mapping delineated bathymetric features. -Mid-ocean ridges -Deep-ocean trenches -Volcanic islands -Seamounts -Fracture zones
What is steady-state? Why is it important to cycles?
Steady-state= inputs balance outputs All cycles want to attain a steady-state condition. Steady-state condition- the proportions of a chemical in different reservoirs remain fairly constant, even though there is a constant flux (flow) of the chemical along reservoirs. —When we speak of global change in biogeochemical cycles, we mean we mean a change in the relative proportions of a chemical held in different reservoirs at a given time. In other words, a change in the steady-state condition.
Why is the Earth's core hot? (Where does the heat come from?)
Temperature increases with depth Potential energy turning into kinetic- impact, turning into thermal Core is still cooling- radioactive decay *Still cooling from accretion*
Compare and contrast Terrestrial and Jovian Planets
Terrestrial: More dense, Made up of refractory materials, Closer to the Sun, Thin atmospheres, Less massive, Heavier elements (can't hold lighter elements), Very few natural satellites, Rotate relatively slow Similarities: Spherical in shape, Dense cores Jovian: Gaseous, Less dense, Farther from the Sun, Thicker Atmospheres, Greater Mass, Lighter elements, More natural satellites, Rotate more rapidly
Define growth rate.
The rate at which the number of individuals in a population increases in a given time period, expressed as a fraction of the initial population.
Why wasn't CDH accepted by Wegener's peers?
The theory was rejected because he could not explain HOW the continents had moved. All of Wegener's evidence was based on OBSERVATION, not EXPLANATION. Could not provide mechanism for continents moving.
Explain the orbital path of the Earth and the reason for the different seasons in the temperate climatic zones.
Tilt of Earth's axis towards or away from the sun creates seasons. When the north pole tilts toward the sun, it gets more radiation = more warmth during the summer. When the north pole tilts toward the sun, the south pole tilts away. So when it's summer in the north, it's winter in the south. (And vice versa)
Identify two examples of UNIDRECTIONAL changes and two examples of CYCLIC changes.
Unidirectional: Evolution Differentiation of Earth's core and mantle Cyclical: Carbon recycling through Earth's reservoirs Water cycle Formation of supercontinents
Be able to organize the objects in the universe by size.
Universe ---> Galaxies ---> Star Clusters ---> Stars ---> Planets ---> Asteroids/Comets ---> Meteorites
Humans are geologic agents, impacting the Earth's land, water (oceans), and atmosphere. Identify at least two specific examples of how humans have negatively impacted the following: (A) Land
Urban sprawl The #1 cause of habitat loss, which leads to lower plant and animal diversity; increases in natural and synthetic pollution Resource mining -Loss of habitat -Depletion of natural resources -Pollution of drinking water Deforestation -Loss of ecosystems -Loss of resources -Increase in atmosphere CO2 #1 reason of deforestation: cows, red meat production, agriculture, farming Farming & Agriculture -Loss of ecosystems -Increase in soil erosion -Increase in natural & synthetic pollution due to fertilizer and pesticide use
What would Earth's climate be like if we had not greenhouse gases?
Very thin atmosphere with cold climate as no gases would be able to trap and absorb heat.
Consider that the deaths of stars eject quantities of heavier elements into space, and that these elements then become incorporated in nebulae from which the next generation of stars forms. Do you think that the ratio of heavier to lighter elements in, say, a sixth-generation star is larger or smaller than the ratio in a second-generation star? Why?
Yes, because the greater generation of the star, the more heavier elements it will have.
Based on the criteria you described in #1, Earth is an example of an open system. So, why is it acceptable for scientific studies to be designed on the assumption that the Earth is a closed system? What is the underlying reasons for scientists to make this assumption in the first place?
[Fourth slide] Allows scientists to eliminate variables; we'd have to deal with energy AND matter. Earth isn't exchanging a lot of matter with space; we focus mainly on energy, allowing us to study Earth as a closed system.
Which of the following was NOT a line of evidence used by Wegener to develop this theory that continents drift? Choose one: A. the distribution of fossil species B. the presence of earthquakes in seismic belts along trenches, ridges, and fracture zones C. matching mountain chains on continents currently separated by oceans D. the location of ancient till deposits and striations that indicated glacial movement toward the interior of continents
the presence of earthquakes in seismic belts along trenches, ridges, and fracture zones (It was not until after World War II that scientists produced maps of earthquake distribution, which indicated the presence of seismic zones along trenches, mid-ocean ridges, and fracture zones—long after Wegener's time.)
