GNM 2137 The World Ocean Spring 2022
Paper 1 Assignment
Due date: February 18, 2022
Total points: 100
PAPER TOPIC: Features of the Deep Seafloor
PAPER SCOPE: In your paper, you should talk about each of the items listed below.
– trenches in the ocean, examples, relation to tectonic plate movements
– island arcs and their associated trenches
– abyssal plains in the deep ocean
– mid-ocean ridges, their features, examples
– hydrothermal vents and their environment
– sediments as the ocean’s memory and recorders of past climate
– sources of sediment particles
– sampling of sediments: different techniques
– economic importance of deep sea sediments
RESOURCES: The primary resource for your paper should be the Endless Voyage video episodes. The information contained there should address many, although not necessarily all, of the items listed above. You do not need to include any tables, maps or charts in your paper. Instead, I want you to accumulate and interpret information from the video series, and then write about it in your paper. In general, you should think of your paper’s goal as explaining the items above to a non-technical audience.
For items with limited or no information in the videos, you should consult some other resources. Specifically, I want you to include at least three (3) other references in your paper. They may be print or internet-based, the important thing being that they are relevant to the topic and come from authoritative sources (e.g. information obtained from the National Oceanic and Atmospheric Administration’s web site would be considered authoritative, while that obtained from somebody’s private web page would not).
PAPER FORMAT: The total length of your paper, including cover page and bibliography, double-spaced and typed in a standard font size. The paper should be written in proper English, paying attention to grammar and spelling. It should have a cover page with your chosen title and your name. The body of the paper should be properly formatted (page numbers, division into appropriately titled sections, perhaps a table of contents). The specific paper organization is up to you – the only important thing is to cover all the items listed above and combine it into a coherent whole.
Summary for The Endless Voyage – Episode 1: “The Water Planet”
Once more, welcome to our course! This, the first episode sets the stage for many of the topics and issues that will be discussed in The Endless Voyage series. In my emails to you, I will list some of the broad topics discussed in each episode. Your goal is to be able to talk about those topics in some detail (e.g. describe them, compare or contrast, list examples etc., as appropriate). I will list certain items parenthetically if they go beyond the scope of this course or there is some other reason why you don’t have to worry about them. So, as we get started, I wish you good learning and enjoy the episodes!
Some of the broad topics in the first episode:
– Earth: the water planet
– liquid water on Earth (don’t worry about the rainfall record in India)
– physical properties of water, their effect on nature, organisms, our planet
– Hubble, expansion of universe, Big Bang theory (here don’t worry about explanation of singularity in early universe; that’s beyond our scope here and is a subject for a physics course)
– (also skip the description of microwave radiation, protosun)
– here they forgot to mention, so let me chime in, the age of the Earth: most commonly accepted number is about 4.6 billion years
– atmosphere on early Earth, oxygen formation, photosynthesis (CO2 refers to carbon dioxide)
– (skip the detailed description of how hydrogen and oxygen may have formed water in early universe)
– two schools of thought with respect to origin of water on Earth’s surface
– water and its importance for life (here skip the detailed discussion of organic compounds and where they may have been formed)
– NASA’s working definition of “life”
– where life may have started on Earth (don’t worry about the details of this extended discussion, but note how many hypotheses include the ocean; we’ll take a closer look at some of these specific oceanic environments, such as hydrothermal vents, later in the series)
– the world ocean: average ocean depth/land elevation
– hypothetical conditions on Earth without the ocean
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Summary for The Endless Voyage – Episode 2: “First Steps”
This episode deals with the history of ocean exploration. It may be a good idea to have an atlas handy when watching the episode, so you can track the voyages and find some of the locations mentioned on a map.
Some of the broad topics in this episode:
– ancient seafarers: Greeks, Polynesians, Vikings
– Captain Cook’s expeditions
– United States Exploring Expedition
– Matthew Fontaine Maury; Charles Darwin
– the Challenger expedition – 1800’s, British
– early oceanographic institutions: Naples, Italy; Scripps Institution of Oceanography, San Diego CA; Woods Hole Oceanographic Institution, Cape Cod MA
– effect of wartime activities on oceanographic institutions; Roger Revelle
– importance of national, international collaboration in oceanography today
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Summary for The Endless Voyage – Episode 3: “Making the Pieces Fit”
This is quite an intense episode, but it shows very nicely how natural sciences work. The starting point are usually observations of nature, and then hypotheses/theories are developed by ingenious scientists to try to explain those observations. There can be several different “ideas” (hypotheses) attempting to explain the same observations, especially when there is conflicting evidence or not enough evidence. All this points to a view of natural scientists as “detectives of nature”, trying to explain how the Earth, its continents and oceans came about. Understanding how this scientific process works is one of the goals of any GNM course. Finally, another note: there are a lot of scientists mentioned in this episode, focus only on those whose names I mention below. Also, you may want to keep that atlas handy as you watch this episode.
Some of the broad topics in this episode:
– “jigsaw puzzle” fit of certain continents, e.g. South America and Africa; pattern of fossils around the world
– Alfred Wegener, continental drift idea, Pangea
– (skip the short discussion of isostacy; for those who take Introduction to Oceanography in the future, we’ll talk about it in that course)
– differences, in Wegener’s time, between American and European/German views of scientific inquiry
– Pacific “ring of fire” (skip the names of individual scientists mentioned)
– World War II and improvements in deep ocean observations
– Harry Hess and Robert Dietz, seafloor spreading hypothesis
– (skip the whole detailed discussion of magnetic field measurements and how they were used in support of seafloor spreading hypothesis; this is fascinating indeed, but is beyond our scope in this course)
– Glomar Challenger, Deep Sea Drilling Project
– the theory of plate tectonics, incorporating both continental drift and seafloor spreading
– use of satellites, GPS (=Global Positioning System), to confirm motion of plates on Earth’s surface
– results of plate tectonics, e.g. mountain ranges on continents, mid-ocean ridges (ridges are undersea mountain ranges)
– comprehensive scope of the plate tectonics theory
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Summary for The Endless Voyage – Episode 4: “World in Motion”
Note: this is another intense episode, so hold tight as you watch it! I will list below the broad topics and some of the important terms that I want you to know. There are also some items in this episode that are beyond the scope of this course, and I will point out those. Finally, for this episode it is ABSOLUTELY ESSENTIAL to have an atlas handy as you watch it, because it refers to numerous topographic features of the ocean and the continents.
Some of the broad topics in this episode:
– tectonic plate boundaries, earthquakes
– three types of plate motion and associated plate boundaries: divergent, convergent, transform boundary
– some examples of divergent boundaries: East Africa, Red Sea, Rio Grande (US), East Pacific Rise, Mid-Atlantic Ridge
– some examples of convergent boundaries: west coast of South America and Andes Mountains, western Pacific and Japan, the Philippines
– since they frequently use the terms, let me remind you that “ridges” are undersea mountains, while “trenches” are the deepest ditch-like parts of the ocean floor
– transform boundaries and associated transform faults, e.g. San Andreas Fault in California, south island of New Zealand
– seamounts (skip the term “guyot”, which is just a flat top seamount); Hawaiian/Emperor Chain
– island arcs and associated trenches, e.g. Aleutian Islands/Trench, Marianas Islands/Trench, Puerto Rico Trench
– Earth’s interior, three major layers: crust, mantle, core (skip the specific mineral names)
– heat, convection in Earth’s interior and how it drives plate tectonics; comparison with other planets
– (skip the discussion of still unanswered questions in plate tectonics; much of it is speculative and beyond our scope)
– use of computer models to predict what Earth’s surface will look like in the future (skip the details of this rather speculative discussion, but note that “predicting the future” based on verified scientific theories is one of the goals of natural sciences today)
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Summary for The Endless Voyage – Episode 5: “Over the Edge”
A very nice and comprehensive episode, with beautiful pictures of the ocean floor and features such as hydrothermal vents (undersea “geysers”) which are found there.
Some of the broad topics in this episode:
– continental margin, consisting of shelf, slope and rise
– continental shelves: shape, resources, formation
– continental slopes, continental rises
– submarine canyons, turbidity currents
– deep ocean floor: abyssal plains
– mid-ocean ridges
– seamounts (again, don’t worry about the term “guyot” which, as you can hear, people pronounce in all different ways!)
– island arcs
– trenches
– hydrothermal vents, discovered by submersible “Alvin”: general description of the environment, physical and biological processes (don’t worry about the behavior of individual minerals such as iron etc.; that’s way beyond our scope in this course; for those who may take Chemical Oceanography in the future, we’ll go into all that there)
– life around hydrothermal vents and its implications for life on other planets
– modern oceanographic instrumentation: side-scan sonar, CTD (stands for conductivity, which measures salinity, temperature, and depth), ROV (stands for remotely operated vehicle), submersibles (such as “Alvin”), satellites with radar altimeters
– most of the deep ocean seafloor is still unexplored
Summary for The Endless Voyage – Episode 6: “The Ocean’s Memory”
In this episode, we continue our exploration of marine geology, which has been the topic of the last few episodes. Here we turn our attention to sediments on the seafloor.
Some of the broad topics in this episode:
– sediments as the ocean’s memory
– sources of sediment particles
– terrigenous sediments
– biogenous sediments
– hydrogenous sediments (e.g. manganese nodules), cosmogenous sediments
– resources from sediments and their economic importance
– sediments as recorders of past climate; attempting to predict future climate by reconstructing the past
– (skip the description of particular techniques such as amount of magnesium in calcium carbonate, or oxygen isotopes)
– information from sediments about Earth’s magnetic field
– limited time record preserved in marine sediments
– sampling of sediments; dredging, gravity corers, piston corers, deep sea drilling
– Deep Sea Drilling Project, the Ocean Drilling Program
– paleoceanography (=study of ancient oceans) and Deep Sea Drilling Project
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Summary for The Endless Voyage – Episode 7: “It’s in the Water”
Another rather intense episode, we’ll skip some parts of it. In this episode, we shift gears to marine chemistry, note that there are many different (“new”) marine scientists talking here.
Some of the broad topics in this episode:
– polar structure of water molecules (don’t worry about terms such as “dipole”); how that structure affects water properties
– ice
– salt in seawater, its sources (skip the comparison of fresh water and saltwater lakes)
– sinks for sea salts
– salinity, its definition, measurements (you can skip the discussion of chlorinity, which is an important topic in a Chemical Oceanography course)
– importance of salinity for seawater density, freezing point of seawater
– importance of seawater density (as determined by salinity and temperature) for ocean circulation
– thermohaline circulation (as the name implies, this is circulation driven by differences in temperature “thermo” and salinity “haline”, which together determine density)
– importance of ocean circulation for exchange of gases, in particular carbon dioxide CO2 (skip the particulars of this discussion such as carbon reservoirs, or CO2 during last ice age)
– (skip the whole discussion of the importance of iron for growth of marine plants; it is way beyond the scope of our course, for those who take Introduction to Oceanography or Chemical Oceanography, we’ll talk about it there)
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Summary for The Endless Voyage – Episode 8: “Beneath the Surface”
This episode discusses layers in the ocean, and two physical properties of seawater, light and sound. Sound in particular has some fascinating properties in the ocean, because seawater is so transparent to it. For example, if you make a “thud” in the ocean at about 1000 meters depth, it can be heard (at that depth) half way around the globe!
Some of the broad topics in this episode:
– ocean structure: epipelagic zone (containing phytoplankton, zooplankton), mesopelagic zone
– main thermocline, seasonal thermocline
– continuing after mesopelagic zone: bathypelagic zone, abyssopelagic zone, hadopelagic zone
– light in seawater, photic zone (skip the subdivision of photic zone into euphotic and disphotic)
– effect of light (or lack thereof) on marine organisms; bioluminescence
– absorption of light in ocean water and how it affects colors
– sound in the ocean, effects of temperature, pressure
– (skip the discussion of magnesium sulfate and how it affects sound in seawater)
– spreading of sound, scattering, shadow zones (note the MANIFESTATIONS of shadow zones, but don’t worry about the details of how refraction forms those zones)
– military applications; SOFAR channel, which stands for “sound fixing and ranging”
– use of sound in ocean research
– use of sound by marine mammals such as whales (by the way, this is known as “echolocation”)
– interrelationship between all four areas of marine science: marine chemistry, marine biology, marine physics, marine geology
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Summary for The Endless Voyage – Episode 9: “Going to Extremes”
A not too intense episode, contrasting tropical and polar ocean environments. The polar environments, particularly Antarctica, are both fascinating and very important for many processes in the ocean. These environments also support surprisingly large populations of marine organisms. Regarding tropical ocean, the big item in this episode are coral reefs, with some beautiful pictures!
Some of the broad topics in this episode:
– the tropics: location, biological productivity
– biological productivity of the polar regions
– coral reefs: structure, organisms (skip the names of individual algae)
– coral structures: branching, platy, encrusting, doming
– polar regions, adaptations of organisms during polar winter
– coral reefs as indicators of past ocean conditions
– influence of polar regions on global ocean circulation
– natural and human threats to coral reefs; bleaching
– human impact on polar environments; chlorofluorocarbons (CFC’s) and ozone hole
– challenges for humans working in polar regions
– differences between the Arctic and Antarctica