Chapter 1-5 Exam Flashcards
(98 cards)
1
Q
Known Ages: Universe, Earth
A
Universe: 13.7 billion
Earth: 4.6 billion
2
Q
What are the steps describing the scientific method?
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Curiosity, observations, hypothesis, experiments, theory, law
3
Q
Big Bang Theory - two major sources of evidence
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Main Pieces of Evidence for BB Theory
1912: Vesto Slipher reported a “red shift” in the “light” energy coming from distant galaxies showing that galaxies were mooving away from Earth
1923: Edwin Hubble and colleagues combined their measurements of galaxy distances with the red shift
Conclusion: the universe is not only in motion but expanding !!!
1964: Arno Penzias and Robert Wilson (ATT Bell Labs) trying to improve microwave communication by reducing antenna noise. Discovered unremovable noise to be background radiation from the Initial Big Bang explosion
4
Q
Hubble’s Law
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Hubble’s Law: Law of Expanding Universe
One of the greatest discoveries in science!
If we know the rate of expansion, we can backtrack to the source and estimate when (and where) the Big Bang occurred!
5
Q
What is a light year?
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6
Q
What are 3 major processes that formed the solar system and planets?
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7
Q
What is the definition of density?
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8
Q
How was the moon formed?
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9
Q
Two major sources of water for formation of the ocean
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10
Q
What were 3 steps in formation of atmosphere and ocean on earth?
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11
Q
So far, the oldest Earth Rocks found have been dated using radioisotopes at 4.28 BY.
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12
Q
Ocean formed about 4 BYA. Life is thought to have evolved soon (100 million years) after the ocean became stable.
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13
Q
How old are fossils of possible first life in ocean (3.5-3.7 BY) and what type of fossil photosynthetic organism was dated at that age?
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14
Q
How are cyanobacteria and stromatolite related and and why are they important?
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15
Q
What do we mean by the oxygen revolution in the atmosphere, when did it start, what organism is thought to have caused it, why is it important to the evolution of animal life?
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16
Q
What is chemosynthesis?
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17
Q
What is a hydrothermal vent, where are they found, what is the energy source for bacteria (the base of that ‘food chain’), and what are the challenges that life faces in that environment?
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18
Q
Percent of Earth’s fresh water that is in the ocean?
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19
Q
Characteristics of World Ocean; average depth, temperature, salt content.
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20
Q
Who were earliest known ocean explorers, and what were their “aids to navigation”?
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21
Q
What was the Library of Alexandria and what is it known for? Who was the first librarian? What happened to it?
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22
Q
What did the following men do that was of major consequence to ocean exploring and/or oceanography? Alexander the Great, Eratosthenes, Columbus, Cook, Franklin, Darwin, Harrison, Nansen, Thomson, and Murray
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23
Q
What were Columbus and other Spanish/Dutch/Portuguese/British sailors in search of in late 1400’s and early 1500s?
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24
Q
Why did Columbus think Asia was so close to Europe? (did it have to do with Ptolemy’s miscalculation of the circumference of the Earth?)
A
25
Whose voyage set out to prove that circumnavigation of the globe was possible
26
What cultural group discovered North America and about when (hint: 985-995 CE)?
27
What was the most famous Chinese invention for navigation? (hint: still in use)
28
Which voyages occurred within the Age of Discovery? What were they in search of?
29
1st Oceanographic Expedition (1872-1876), aboard the HMS Challenger, what was the hypothesis that was tested? Who were the chief scientists? Did they only study biology?
30
What did Captain Cook use that John Harrison built and perfected??
31
What major activities did Captain Cook accomplish and why was Harrison’s invention so important to him?
32
How did early Northern Hemisphere navigators determine latitude in the northern hemisphere?
33
Who sailed on a ship named the HMS Beagle and what theory do we attribute to him?
34
How does longitude relate to time on earth? How many degrees does Earth rotate in one hour? How does Central Standard Time (this is Baton Rouge time) relate to UTC (Universal Time Coordinated at Greenwich, England)?
35
When we change to daylight saving time (in spring), do we add or subtract an hour from our clocks?
(Hint: we spring ahead and fall back)
36
Can you figure out your longitude while crossing the Atlantic Ocean basin if you depart England with a clock set with Greenwich time? Be ready for a question!
37
In what decade, were the first satellites launched to measure ocean properties?
38
What is the “ALVIN” and be able to list a few of its most famous discoveries.
39
Wegener proposed continental drift based on 4 main pieces of evidence (what are they?)
40
What are Pangaea and Panthalassa
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Where did Wegener go wrong (i.e., why didn’t anyone believe him?)?
42
How did measuring seismic (earthquake) waves help scientists understand the structure of the Earth and ultimately continental drift?
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How did Harry Hess explain the mechanism of seafloor spreading?
44
How old is the oldest ocean seafloor? Are continents older than that? Remember how old the oldest rocks are on earth (> 4 BY) (from Chapter 1).
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Subduction zones have deep earthquakes and more violent activity than do the spreading centers which have shallow earthquakes.
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How do the terms convergence and divergence relate to subduction zones and spreading centers?
47
What was the geologic feature at the Mid-Atlantic Ridge that the submersible ALVIN first photographed?
48
What makes the interior of the earth so hot?
49
Understand radiometric dating using radioisotopes and concept of half -life.
50
How did discovering magnetic striping of seafloor lead to our knowledge of magnetic pole reversals? How often have they occurred on average acc to the documentary “’Magnetic Storm”? How long ago was the last magnetic pole reversal?
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Palaeomagnetic data has multiple uses: to measure spreading rates of plates, to calibrate the geological time scale, and to reconstruct continents.
52
Know about the nature of lithosphere and asthenosphere as they relate to plate tectonics. Which is rigid and which can move the lithospheric plates?
53
Can you recognize the three types of plate boundaries; convergent, divergent, transform?
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How did a hot spot form the Hawaiian island chain?
55
What is the Curie point?
56
What is isostatic equilibrium and why is it important in understanding vertical structure and motions beneath continents and glaciers?
57
Mapping bathymetry of the ocean floor- major advances over time
58
How does a multi-beam echo-sounder work? What is the simple equation to compute depth based on speed of sound and travel time of pulse from ship to bottom and back?
59
Structure of ocean basins – what are ridges, trenches, abyssal plains/hills, seamounts, guyots?
60
Features of a passive continental margin- know characteristics of continental shelf, slope, and rise, and the location of the shelf break.
61
What is an active margin? What is a passive margin? Why are Atlantic margins called “passive” and Pacific margin “active”?
62
How does the structure of a continental margin differ when the margin is active (Hint: Lots of canyons and continental shelf is typically narrow)
63
What is the feature that cuts into the shelf and slope on a passive margin and is a major conduit for the transport of sediments to the continental rise? (seaward of river mouth in northern Gulf of Mexico; associated with earthquake activity in other regions)
64
Are turbidity currents and deep-sea fans related?
65
When did the most recent phase of sea level rise start? (at the end of the last sea level low stand 18,000 yrs ago!)
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What is major cause for sea level changes over the last 250,000 years?
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How does the depth of the continental shelf break relate to sea level change??
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Where was the coastline 18,000 years ago?
69
What caused the massive amounts of salt to be deposited on the northern Gulf of Mexico continental slope? (Hint: what is evaporation?) and when did the salt deposition start? Which came first, the salt or the sediment? Where did the sediment come from?
70
What is the main source of energy for chemosynthetic communities on the continental slope in the Gulf? Is this the same energy source as the chemosynthetic communities at the hydrothermal vents at the East Pacific Rise?
71
Frozen methane (gas hydrates) is abundant on the Louisiana continental slope. When it thaws, gaseous methane is released into the ocean and makes its way to the atmosphere. Why should we be concerned about using methane as a source of energy?
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How would oceanic warming impact frozen methane that is found on continental slope of NW Gom?
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Ocean sediments are important because (1) they provide a record of ocean basin history, (2) They provide a record of global climate change, (3) they provide a record of bottom physical processes (bottom currents, etc.)
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Classifying sediment by decreasing particle size: Boulder, cobble, pebble, granule, sand, silt, and clay. Last three are what we typically see in Gulf of Mexico!
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For sand-size and coarser grain sediments, the larger the particle, the stronger the current must be to erode the material. Because clays are the smallest and lightest sediments, they are transported great distances and form pelagic clays in deep ocean basin.
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Forces for sediment transport include gravity, wind, waves, turbidity currents, oceanic currents, glaciers, and icebergs.
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How do we sample for sediments at sea? Box corer (gives only near surface sample) and piston corer (gives deeper, longer record, used more often in deep water).
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* Sediment types according to sources: terrigenous (derived from land- from rivers, glaciers, desert dust), biogenous (calcareous and siliceous), cosmogenous, hydrogenous. Most sediment deposits in the ocean are a mixture of terrigenous and biogenous particles.
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About 50% of the surface area of continental margins and ocean basins are covered by terrigenous sediments. By volume, continental margins are home to much more than 45%.
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What is the major source of terrigenous sediments globally? (Hint: what are rivers?)
81
What type of current carries sediment to the deep-sea fan?
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* Calcareous (calcium carbonate) sediments include cocolithophores (phytoplankton) and foraminifera (zooplankton). Siliceous (made of silica) sediments include diatoms (phytoplankton) and radiolarian (zooplankton). Many are microscopic! Zooplankton are marine animals and phytoplankton are marine plants, both are forms of plankton which live in sunlit areas of ocean. Study the slides of these planktonic organism and be able to recognize major forms: forams, simple diatoms, coccolithophores.
83
* A biogenous sediment that contains more than 30 percent of the hard parts (shells) of planktonic marine organisms is called an ooze. The silica-rich residues give rise to siliceous ooze, the calcium-containing material to calcareous ooze. The coastal feature called “the White Cliffs of Dover (England)” is an example of an uplifted oceanic calcareous ooze. Foram ooze material were used to build at least some of the pyramids of Egypt.
84
*Diatomaceous Earth (DE) is made from crushed diatoms (made of silica), the sharp edges can pierce the chitin of insects (fleas, cockroaches, ants) and kill them from the outside (when applied) or from the inside (if ingested).
85
* The fine-grained fallout of biogenic and terrigenous sediments that settle to the deep-sea floor through the water column is called pelagic sediment. Continental shelf sediments are called neritic sediments.
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* On a typical shelf, the coarsest-grain sediments (larger sands) are found closest to the coast. One exception is sediments carried by glaciers and icebergs that carry very coarse sediments (as large as boulders) long distances from land.
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*Rate of sedimentation is almost always higher on continental shelves than in the deep ocean. Shelves are closer to terrigenous sources and higher in biological productivity (source is biogenous sediments).
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* On the deep-sea floor, thickness of sediments varies from near zero near the mid-ocean ridges to thickest on the abyssal plain. This is because the abyssal plains are older and thus have had time to accumulate more sediment.
89
Sediments undergo EROSION, TRANSPORT and DEPOSITION in that order. What do those terms mean in terms of sediment motion?
90
Waves at the shoreline are a major source of erosion of sediments in shallow water at and near the coast. Hurricane waves can erode sediments in deeper water. We will learn more in the WAVES lecture!
91
Strong winds can erode, transport and deposit sediments associated with sand dunes, this is called Aeolian transport
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* Clays: About 38% of deep-sea sediments are clays. Clays come mainly from rivers and from deserts. The Saharan red dust travels in the upper atmosphere occasionally to the Gulf of Mexico. If you sit on outdoor furniture covered in very fine red particles it is highly likely that is Saharan red dust!
93
* The calcium carbonate compensation depth (CCD) is at about 4500 m in tropical waters. It is the depth below which CaCO3 is dissolved. Below the CCD, calcareous oozes cannot accumulate because in deep water pressure is high and temperature is low resulting in a higher concentration of CO2, which leads to formation of carbonic acid, which dissolves calcium carbonate. In contrast, siliceous materials are not affected. As a result, siliceous oozes predominate at greater ocean depths.
94
*Be able to name several tropical organism sources of calcium carbonate often yielding thick sequences, like the expansive carbonate continental shelves of the Bahama Banks. (sources of biogenous calcium carbonate are hard and soft corals, coralline algae, foraminifera)
95
* Ooids are small round hydrogenous sediments formed from the precipitation of calcium carbonate in shallow warm seas on a condensation nucleus. They require strong currents to form and they accumulate in underwater shoals that are a few feet from the water surface.
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The Bahama Banks are an excellent example of conditions where ooids form and create oolite sands and shoals. These shoals played a major role in the thick sequences of calcium carbonate comprising the Bahama banks.
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Calcareous sediments over time can form limestone rock (often found as beach rock in tropical environments).
98
Manganese nodules are very slow growing ancient hydrogenous sediments created from precipitation of minerals from the ocean, typically a few inches in diameter, first discovered on Challenger Expedition, mined from deep ocean floor!
