OCS 1005 - EXAM 1
2) You should know what percentage of the Earth is covered by the Ocean
71% of the earth's surface is ocean • 97% is salt water • 2.5 is fresh water (69% is in glaciers, 30% in ground water, >1% is in permafrost {the icy layer of soil we find in the arctic)
2) You should know when the Earth and oceans formed
Approximately 5 billion years ago shortly after the solar system was formed
1) You should know what the Big Bang is and when it happened
Explosion that catalyzed the formation of the universe 13.7 billion years ago
8) You should know how old the oldest ocean sediments are and why there are no sediments older
No existing crust older than this because the plates interact at convergent boundaries and are subduted and eventually recycled.
3) You should know what the earliest life form was in the fossil record and how long ago it lived
A chain of Bacteria 3.5 billion years ago -- Didn't require oxygen -- Photosynthetic using light to create energy and food -- Released oxygen
3) What is the chronometer, how does it work, and why is its invention significant?
A clock that uses a spring instead of a pendulum and It makes the accurate calculation of longitude at sea possible
Introduction to Oceanography
6 questions
Structure of the Earth and Continental Drift
7 questions
5) You should know what percentage of the Earth's crust is in the oceans
70.8 percent (71%)
3) You should know the sequence of events that leads from a question to the formation of a theory or law
1. Problem 2. Collect information 3. Hypothesis 4. Test hypothesis 5. Theory → see definition for explanation 6. Law → see definition for explanation
History of Oceanography
12 questions
Plate Tectonics
13 questions
Ocean Basins
19 questions
Sediments
20 questions
Scientific Method
3 questions
5) You should know the average depth of the oceans
3800 m (12465 feet)
Origin of the Earth and Oceans
5 questions
1) You should know what bathymetry is and three ways it is measured
Bathymetry- the contours of the ocean floor. • Historically, sounding were taken lowering the weight on a marked line to measure the depth in a particular location. • The "steam wench" and a marked line was used in the challenger expedition to measure bathymetry. • The sinking of the titanic in 1912 prompted the invention of the sonar devices to detect ice burgs in front of ships. This technology was then adapted into what we use today to measure the depth of the ocean - echo sounders. Echo sounders- generally mounted on the hull of a ship, it sends out a pulsive sound and when that sound wave hits an object like the bottom, it is reflected back and the echo sounder detects the returning echo. • Depth= V (t/2) where "t" is the time it takes for the echo to return to the echo sounder. The reason it is divided by 2 is because the sound travels the entire depth of the water column twice • V=1500 m/s in sea water ; T=2 → depth= 1500 (2/2) • Echo sounders are very useful in finding precise depth at a single point or a long straight line Multi-beam sonars - extend the range over which depth can be recorded for a single ship. The beams extended out in a fan from the echo sounder at the bottom of the ship and this allows data to be recorded along a wider slot along the ships track. o Different colors represent varying heights • The crew for the USS guardian had three version of charts for the area in the pacific where they were operating. TWO of these were updated with the latest information but the third one was not. They were using the un updated chart. o They also didn't compare the different chart versions to see that the location of this particular pristine coral reef was different by 8 miles o The bad charts along with human error led this multi-million dollar mind sweeper on this reef where it eventually had to be cut into pieces to be salvaged Satellite Altimetry- measure variations in the elevation of the surface of the ocean. o There are slight variations in the elevation of the surface of the ocean due to the underlying bathymetry. This is because the pull of gravity varies slightly across the earth. o The satellite can measure these variations in surface elevation Gravity from the seamount pull water in to its side and so forms a small mound of water over its top. o Can collect data over a much wider area and can do so continually as they rotate the earth • Putting together all our information we now have a detailed view of the ocean basin • The ocean floor is NOT smooth • The topography across north America is compared to the bathymetry across the Atlantic ocean o North America is dramatic including the rocky mountains and the sierra Nevada mountains but these features are dwarfed compared to what we see crossing the Atlantic ocean o Atlantic ocean has the most prominent feature being the mid ocean ridge • Most of the surface of the earth is in the oceans • Over 50% of the surface area of the earth is in the ocean at a depth of 3000 meters • Over half of the surface area of the earth is what we might call the deep sea
2) You should know the types of waves in earthquakes and their relative speed of travel in relation to each other
Body Waves: P waves and S waves only they travel through the planet. o P waves- primary waves - move particles forwards and backwards • Can travel through both solid and liquid matter. • Travel faster and they will arrive at a seismograph the instrument that measures the waves in the earth with earthquake activity faster than the secondary waves • As they encounter different densities within the earth there speed changes and they become bent. o S waves- secondary waves - portion of the wave in which particles are being moved up and down • cannot travel through liquid, only through solid matter o Surface waves- moves the surface of the crust up and down 1. The focus is the point at which the earth quake is generated 2. surface waves are traveling along the earth 3. and the same time both primary and secondary waves move out from the focal point Seismograph o 0 point being the moment that the earth quake happens o P wave → S wave → Surface wave • Scientist were able to use this information about earthquakes in terms about what we know about the waves and how they travel and what they can travel through to determine what the structure of the earth was
5) You should be able to define buoyancy and isostatic equilibrium and know how these forces affect the lithosphere
Buoyancy is the ability of an object to float in a fluid by displacing a volume of the fluid that happens to be equal in weight to the objects weight • Reason why mountains don't sink • Reason why the hard, rigid, outer lithosphere layer doesn't just sink down into the pliable, semi liquid asthenosphere layer o Example: how a ship floats on water: Empty ship floats higher because it weighs less compared to a ship containing cargo where the water is displaced a greater volume of water and still being able to float due to the forces of buoyancy. o Buoyancy keeps the lithosphere floating above the asthenosphere we talk about it in terms of isostatic equilibrium. Isostatic equilibrium (The balanced support of lighter material in a heavier, displaced supporting material) is that there has to be an overall equilibrium across a lithosphere plate. If one part of the plate is heavier it will sink down deeper than another part of that plate. o But if erosion occurs and that material from the mountain gets moved around that portion of the plate will rise up some while another potion will sink down. The entire plate at any given time is in isostatic equilibrium. • Isostatic equilibrium is in flux o Erosion causes the mountain to become lower and takes the material that used to make up that mountain and deposits it on either side of the continental crust then we will have UPLIFT of the lithosphere underneath the mountain and subside on either side so the plate is having to sink down deeper o Overall we have the SAME equilibrium we have just redistributed it causing certain portions of it to uplift and other portions to subside
7) You should know the theory of continental drift, the early evidence for it, and the mechanism that drive it
Continental Drift - theory there was once one super continent (Pangea) that split/drifted o hypothesis proposed by Alfred Wegner o His evidence: the shape of the continents and fossils o Once the structure of the earth was known and there was a plausible mechanism for this drift, his hypothesis became a theory. Drift - the movement of the solid plates in the lithosphere. o The heat source is the radioactive decay at the center of the earth it heats up the liquid part of the mantle the asthenosphere, some of that material rises up it cools as it nears the surface of the lithosphere and drops back down to the core where its reheated and this can cause the actual movement of the plates on the surface of the earth. Convection- a circular current in which water is heated from the heat source at the bottom, rises up and is cooled at the top, then falls back down and that creates the circle. o This is what we think is going on in the earth! The heat source is the radioactive decay in the center of the earth. It heats up the liquid part of the mantle in the asthenosphere and some of that material rises up. It cools as it's near the surface of the lithosphere and drops back down to the core where it's reheated. CAN CAUSE THE ACTUAL MOVEMENTS OF THE PLATES ON THE EARTH. o Convection currents are large and slow moving mantle plumes but the material in the mantle the pliable asthenosphere is heated near the core and rises up is cooled as it moves along the lithosphere and then drops back down where its then again heated at the core and this is the mechanism for the drift of the plates Fossil evidence that showed that at one time the landmasses had been joined. o Dinosaur that was called Mesosurus that was found only in Southern South America (Argentina) and southern Africa in areas that would have joined each other if the continents were fitted together. o Fossil ferns, Glossoptoris, were found in south America, Africa, India and Antarctica all the southern land masses
3) You should know the different types of continental margins and their characteristics
Continental margins- submerged outer edge of a continent, areas of the oceans that are adjacent to the continents. o Passive margins --> face divergent plate boundaries • Little earthquake activity • Atlantic • There is a divergent plate boundary in the middle of the ocean where the mid-Atlantic ridge is formed. The margins on either side are facing this divergent plate boundary o Active margins --> face convergent boundaries • Earthquake and volcanic activity • Pacific • An example of an active margin is found on the west coast of South America along the Pacific Ocean these margins face a convergent plate boundary. This is an ocean-continent convergent boundary and the denser oceanic plate is sub ducted below the continental plate forming a trench. There is earth quake activity associated with the subduction and the partial melting of the subductive plate fuels volcanic activity on the continental plate • Extends from the beginning of the continent out to the the beginning of the deep ocean floor
4) You should know the different parts of a continental margin (continental shelf, continental slope, etc.) and their characteristics
Continental shelf- submerged outer edge of the continent and is still composed of the same type of crust as the rest of the continental plate o Shallow submerged extension of a continent o The width is determined by how close it is to a plate boundary o Most of the material composing the shelf comes from the adjacent continent o The weight of these sediments depresses the weight of the continental shelf and that is why its submerged o Continental shelves are affected by sea level. In the past, sea level was much lower than the present sea level. Sea level will affect how much of the continental shelf is exposed and can be eroded by wind and waves. The sediment can then be transported away • Extends from the shore to an abrupt transition called the shelf break where we move from the continental shelf to the continental slope. Continental Slope- This is a relatively steep area with a rapid change in depth. o Transition between continental shelf and deep-ocean floor o Steeper grade that continental shelf o Slopes at active margins are generally steeper than at passive margins o Formed of sediments that reach the edge of the shelf. Continental Rise- LARGE accumulation of sediments here o Only found at a passive margin o Formed by accumulated sediments at the base of the continental slope o Most sediment is transported by turbidity currents and then shaped by deep ocean currents Deep ocean basins- areas away from the margins that are characterized by grid systems, sediment covered plains,
4) You should be able to define density and know how it affects the transmission of waves in earthquakes
Density: the mass in any given unit of volume • If your planet has a density gradient then the waves become bent • If there is a change in density meaning that there is more mass in a given unit of volume then the speed of the waves will change and they will become bent or refracted as they move from something of one density to an area of another density and there speed is changed.
2) You should know the different types of plate boundaries, be able to characterize the features of that boundary, and give an example geographically of each type of boundary
Divergent- where two plate boundaries are moving apart magma from the asthenosphere rises and creates new crust. o EX: Mid Atlantic ridge where two plates are moving apart and new crust is being formed o New crust is formed as the plates move apart, a ridge forms and there are many small volcanoes. The mid-atlantic ridge 1) at a crack in the lithosphere, magma rises to create new basaltic crust 2) the rift continues to open and there are volcanoes and earthquakes associated with this area 3) the rift continues to widen and is submerged, creating a new ocean basin o This is occurring at the rift valley in Africa is thought to be formed as lithosphere is being pushed upward by a super plume of magma and then cracks and pulls apart. o As the crust continues to pull apart the red sea becomes wider and a portion of the continent will break away by the rift valley. • Marie Tharp - her vision and common sense intuition revealed the Mid-Atlantic Ridge was a divergent boundary and so changed the debate on plate tectonics -the axis of spreading cannot occur in a straight line on a curved surface and a fault forms where two plates move past each other Convergent- where two plates are moving towards each other and interact either one plate moves underneath the other plate or the two plates collide and mountains form o EX: Plate boundary on the west coast of south America- one plate is slipping below the other 1) Ocean continent Convergence- lighter continental lithosphere rides up over the denser oceanic lithosphere and a trench is formed and crust is recycled o The denser oceanic plate is subducted below the continental plate, a trench forms and there are deep earthquakes as the plate subsides. The partial melting of the plate in the asthenosphere causes magma to ride and volcanoes sometimes form on the continental plate. This is occurring off the west coast of south America o The denser oceanic plate dives under the continental plate causing a trench, deep earthquakes, and the formation of volcanoes on the continent. Western south america, Pacific Northwest USA o At constructive boundaries, new crust if formed. At destructive boundaries, plate is destroyed 2) Ocean-Ocean Convergence- the older, cooler, denser oceanic crust will be subducted under the other plate and deep ocean trenches and island arcs are formed o The plate that is denser is subducted, this will be the older plate. Because it has had more time to cool, it is denser than a younger warmer plate. Ex: convergent boundary near Japan o As the subducted plate is melted magma rises and volcanos form. This time on an oceanic plate and creates an island arc such as the Japanese islands o Maga may also rise due to the melting plates some distance away from the isands and cause a divergent boundary to form o Tells us the location of the subduction plates which tells us the shallow earthquakes occurring at the location of the boundary where the trenches formed and deeper earthquakes occurring farther away as the plate is subducted deeper 3) Continent-Continent Convergence- the two plates of equal density are compresses and folded and mountains form o Example: Himalayas where India is colliding with Asia Transverse (transform) - where two plates slide laterally past each other. o Ex: San Andreas Fault on the west coast of the United States o Crust is neither created nor destroyed as the plates move past each other. San Andreas fault, mid-ocean ridges Breakup of Pangea - Plate tectonics led to the breakup of Pangea, the original supercontinent - Ocean basins formed at divergent boundaries - Mountain ranges and trenches formed at convergent boundaries
11) You should know how the Hawaiian islands were formed
Formed as the oceanic plate there on moved over the stationary hotspot
5) What areas did the Vikings colonize and explore?
Greenland and north America
7) What is the major finding of the Fram expedition?
Initiated polar oceanography and demonstrated that there is no landmass in the Arctic
10) You should know what a mantle plume and hotspot are
Mantle Plumes: continent sized columns of superheated mantle originating at the core mantle interface o These plumes may be responsible for some of the epic eruptions of lava that occurred in the past over India and in the Pacific Northwest and led to one of the greatest mass extinctions in history o Using earthquake wave velocities, the mantle plume below the Hawaiian hot spot has been mapped Hot Spot: the surface expression of a stationary source of heat in the mantle (like a plume) o Magma flows from the crust forming volcanoes and islands o Hotspot below Yellowstone national park which fuels the hydrothermal activity in the park including the famous geysers
10) What oceanographic variables do satellites measure?
Measure surface temperature, florescence (chlorophyll), sea surface height, ect.
2) You should know what an ocean basin is
Ocean basin is the sea floor beyond the continental margin where the transition from thick to thin denser granite occurs.
9) You should know what the differences are between the bathymetry of the Mid-Atlantic Ridge and the East Pacific Rise and why
Ocean ridges- mountainous formations at spreading centers • average spreading rate for the Mid Atlantic Ridge is 3 cm per year • average spreading rate for the East Specific Rise is about 18 cm per year (slower spreading rate) • the rate of spreading determines the bathymetric features o In a fast spreading system will look smoother like the East Pacific rise because the features are spread over a greater distance. No pronounced central rift valley o Slower spreading rate of the Mid Atlantic Ridge concentrates the features in a smaller area, it also, has a more pronounced central rift valley. Looks smoother sue to the accumulation of sediments. Mid Atlantic ridge- sediment accumulation changes the surface expression of the ridge. There is greater sediment accumulation the farther you get away from the spreading center because the crust is older and has had more time to accumulate sediments. • Spreading at a divergent boundary does not happen in a straight line because the earth is not changing in size, as the spreading occurs, it must be broken by transform faults • Ridge system must occur in segment's offset by transform faults
1) Who were the groups of people who are considered early ocean explorers? What was the library of Alexander?
Polynesians (20,000 years), Vikings (1000 CE (AD), & Chinese (1400 CE (AD) o People were first driven to learn more about the ocean and the size and shape of the earth due to MONEY. o The establishment of trade routes and the discovery of new wealth required better navigation and understanding of currents and winds o The Library at Alexandria in Egypt during the 3rd century BC was a meeting place for scholars, explorers, and merchants to exchange information.
9) What are some of the new technologies that oceanographers are using today?
Remotely Operated Vehicles (ROVs)
14) You should know what a seamount and guyot are and how they are formed
Seamounts- volcanic projections that do not reach the ocean surface o Formed near spreading centers, the volcanic activity, the magma chamber with passages of magma coming up though the plates can form these volcanoes o As the plates move apart the seamount is carried away and is submerged and is no longer active because it is not loner near the active magma chamber o As the mountains move away from the spreading center if there's enough sediment accumulations it could become an abyssal hill → increased fish activities Guyots- former seamounts that have flat tops and may have reached the surface and been eroded
12) You should know how sediment accumulation affects the bathymetry of a spreading center
Sediment accumulation changes the surface expression of the ridge. There is greater sediment accumulation the farther you get away from the spreading center because the crust is older and has had more time to accumulate sediments.
20) You should know what stratigraphy and paleoceanography are
Stratigraphy- analysis of layered sedimentary deposits Paleoceanography- study of the oceans past o Important when looking at how the earth has changed due to past climatic histories • At the end of the cretaceous period a huge meteor impacted the Gulf of Mexico. Cores taken from this region, a distinct layer called the ejectolayer, this layer is the layer that was ejected directly from the impact of the crater and laid down within just a few days of the impact. o Fireball layer - as it concocts of dust and ash fallout from the impact o By dating the core we can get a precise time on when the event occurred.
3) You should know what the pattern of earthquake location and depth tells us about plate boundaries
Tells us the location of the subduction plates which tells us the shallow earthquakes occurring at the location of the boundary where the trenches formed and deeper earthquakes occurring farther away as the plate is subducted deeper
2) What do the Polynesian stick maps show?
The shells represent islands the distance between the shells is not the actual distance between islands but a relative distance that takes into account the prevailing currents and winds. We might say the distance between shells represents the travel time between the islands.
4) What are the inventions of the early Chinese explorers?
Undertook planned expeditions utilizing many new technological advances like the central rudder (allowed greater maneuverability of large ships) and compass (gave them an accurate sense of direction).
5) You should know how the early atmosphere is different from the atmosphere today
o Early atmosphere had no oxygen • Lack of oxygen was critical to allow the formation of complex, organic molecules (amino acids), the building blocks of life • Composed of Carbon dioxide, nitrogen, water vapor, ammonia, and methane
1) You should be able to define experiment, hypothesis, theory, and law
o Experiment - a test that simplifies observation in nature or in the laboratory by manipulating or controlling the conditions under which the observations are made o Hypothesis - informed guess. A speculation about the natural world that can be tested or verified or disproved by further observations and controlled experiments. o Theory - a statement of a relationship that is accepted by most scientists ~ ~ Theories are strengthened when new facts support them and modified or rejected when facts contradict them. o Law - principles explaining events in nature that have been observed to occur with unvarying uniformity under the same conditions.
1) You should know the 4 different disciplines of Oceanography
o Physical - the study of currents and tides o Geological - the study of plate tectonics and the layers of sediment we find at the ocean floor o Chemical - the study of water chemistry such as what kinds of nutrients are dissolved in the oceans and how organisms use them o Biological - the study of all the organisms that live in the ocean
12) European Explorers: (4) The Basque sailors of Spain were fishing for cod off Newfoundland in the 1300's; Columbus sails to north America in 1492, nearly 200 years later
o Prince Hennery of Portugal • Promoted and taught navigation o Christopher Columbus • "first" European to visit North America though he mistook his location for India o Ferdinand Magellan • His crew circumnavigated the globe in 1522 • Proved that the oceans were connected and that it was possible to sail completely around the globe o James Cook • Mapped New Zealand, the great barrier reef, south Georgia (nearly Antarctica), west coast of North America, and "found" Hawaii
3) You should know what percentage of total water on the Earth is contained in the Ocean
• 97% of total water is in the ocean (salt water)
13) You should be able to give a short description of each phase of the Wilson cycle and cite an example
• A summary of plate movement that describes how ocean basins open and close Stage One: EMBRYONIC o Divergent plate boundary formation of a rift valley. The ocean basin itself has not started to form o Motion: Rift flank uplift, rift valley subsidence o EX: East Africa Rift Valley Stage Two: JUVENILE o Divergence (spreading) o Features: narrow sea with matching coasts (because little time for erosion), ocean ridges formed o EX: red sea Stage Three: MATURE o Motion: divergence spreading o Features: ocean basin with continental margins. Ocean continues to widen at oceanic ridge. o EX: Atlantic ocean, Arctic ocean Stage Four: DECLINING o Motion: convergence (subduction) o Features: Subduction begins. Island arcs nd trenches form around basin edge o EX: Pacific ocean Stage Five: TERMINAL o Motion: convergence, collision, and uplift o Features: oceanic ridge subducted. Narrow, irregular seas with young mountains o EX: Mediterranean sea Stage Six: SUTURING o Motion: convergence and uplift o Features: mountains form as two continental crust masses collide, are compressed, and override o EX: inda-eurasia collision, Himalayas
13) You should know what turbidites are and how they are deposited
• A type of pelagic sediment • Deposits formed by the action of turbidity currents • Graded layers of terrigenous sand embedded with smaller particle sediments • Episodic events so we end up with different size particles
9) You should know where rates of sediment accumulation are high
• Amount of marine sediments does not always correspond to the size of the area of the ocean • Areas that may be small in size might have a lot of marine sediments • Continental slopes have the greatest accumulation of sediments about 41 percent and also the area where sediments are the THICKEST
6) You should know what keeps portions of the interior of the Earth liquid or pliable
• Asthenosphere- plastic/ pliable layer of the earth that Is hot partially melted rock • If the earth had simply cooled from the time it was a molten mass, it should be completely cooled and is solid today • Radioactive decay (the action of atoms splitting apart) is the source of heat that keeps the asthenosphere pliable. o Radioactive decay us happening all the time in the core of the earth and every time these atoms split or decay heat is released so we have a continual source of heat in the earth the keeps the asthenosphere pliable.
12) You should know what a terrane is and how it is formed
• At an oceanic- Continent convergence, the plate is subducted • Areas of shallower bathymetry (plateaus, ocean ridges, island arcs) can be squeezed and sheared onto the continental plate to form terranes o Areas of shallower bathymetry (lower density rock) are sheared off on the continent and not subducted o Over time, material is accreted at the edge of the continent o Over time, the location of the subduction zone and the trench will change as more material is added to the continental plate o Sometimes portions of denser ocean crust are deposited (ophiolites) o Almost the entire state of Alaska has been built from terrains
7) You should know where we find the least accumulation of sediments in the ocean and why
• At divergent boundaries, the seafloor is new and there is little accumulation of sediment • Sediments are subducted at convergent boundaries
4) You should know the four different sediment by source types and their basic characteristics
• Biogenesis o These are sediments that have an organic source such as the shells of marine organisms. ONE of the two most dominant sediment types o Oozes o Dominant in the deep ocean floor o Biological origin mostly plankton o Composed of silica and calcium compunds o Form natural gas deposits over time o More abundant in areas where there is high planktonic production in the water column -continental margins -upwelling areas • Hydrogenous o Sediments that are formed from the precipitation of dissolved minerals often due to the activity of bacteria o Not common and are found in smaller quantities along with the dominant sediment type in the given location o Formed from minerals precipitated from seawater o Sources include: -hydrothermal vents -leaching of minerals from rocks and fresh crust -Substances transported to the ocean by rivers o Authigenic sediments- formed in the place they now occupy. o Ex: manganese nodules - precipitate onto a sediment grain on hard objects. Over time the accumulation grows. First discovered on the challenger expedition. o Form due to chemical reactions occurring on particles of the dominant sediment • Evaporites o Different salt compounds that from at different points during the evaporative process (as salinity increases) • Ooliite sands o Formed by precipitation of calcium carbonate o In shallow, warm waters with high productivity o Autotrophs (plants) use up carbon dioxide and make seawater less acidic o Found in the Bahamas • Cosmogenous o Derived from dust from space and debris from meteorites o Rare but clearly distinguished by their extraterrestrial materials o Extraterrestrial origin -interplanetary dust -impacts by comets and meteors -micro tektites o Ex: tektite spheres 5) You should know how terrigenous sediments are transported • Derived primarily from erosion of the land or continents. The dominate type in the continental margins but are also a large component of sediments in the abyssal plains As their transported their off the continental slope • Transported: o Sediments are eroded from the continent by wind and rain and are carried via rain water to rivers and streams and then into the ocean where they are deposited on the continental shelf. THEN are transported to the continental slope and the abyssal plain. At convergent plate boundaries the sediments are subducted and recycled as their melted into the mantle and can return to the continent through volcanic activity. o Transported by RIVERS (most common) ex: Mississippi delta o Transported by wind (Sahara desert) transported by wind and then deposited into the ocean • ONE of the two most dominant sediment types
14) You should know what oozes are, the different types, and what they are composed of and where they are found
• Biogenous sediments • Composed of the rigid remains of organisms (primarily plankton) • If a sediment contains at least 30 % biogenous material, it is termed an OOZE • Accumulation rates of 1-6 cm every 1000 years o Depends on the balance between abundance of the organisms that contribute to oozes and the rate of accumulation of terrigenous material. 1. Calcareous Oozes : EXAMPLE: white cliffs of Dover in the United Kingdom formed by thick deposits of calcareous oozes hat went under lithification and were lifted by plate tectonics o Primarily found in pelagic deep sea areas o Form primarily from foraminifera and coccoliths o 48% of the surface of the deep seabed is covered by calcareous oozes. o Shells containing calcium dissolve at greater depths due to - increased ocean acidity by a greater amount of carbon dioxide being dissolved at depth -increased solubility of calcium carbonate under pressure and in cold water o CCD determines pattern of accumulation of calcareous oozes o Example is near Antarctic an arctic ocean: - At depths above the CCD calcium carbonate sediments can accumulate and the rate of accumulation is GREATER than the rate of dissolution - Below the CCD no calcareous oozes will be found because the rate of dissolution is equal to the rate of accumulation - Shallower at the poles because the water here is colder and because the water is more acidic because cold water can absorb more carbon dioxide. 2. Silicious oozes • Dominate in highly productive ocean areas such as the southern ocean, the equator, and the upwelling areas such as off the coast of south America • Formed from radiolarians and diatoms • 14 % of the surface of the deep seabed is covered by silicious oozes • Predominate at greater depths and polar regions • Silicia does not dissolve as quickly as calcium carbonate • Diatom oozes are found in areas where there is high diatom production (Southern Ocean near Antarctica) • Radiolarian oozes more common in equatorial upwelling regions this region while production has generally lower nutrient levels that the Southern Ocean • Transport to the seafloor o Compaction into fecal pellets speeds the sinking rate of these particles to the seabed
6) What is the significant contribution to science that Eratonthese make?
• Calculated the size and shape of earth and invented latitude o Latitude: he drew evenly spaced lines parallel to the equator, though his placement was not always quite right. Measured as the angle between a line from earth's center to the equator and a line from earth's center to the measurement point. o Longitude: much more difficult because the distance between the lines varies with latitude. Measured as the angle between a line from earth's center to the measurement point and a line from earth's center to the prime meridian (runs through the north and South Pole directly through Greenwich, England. Could be determined using a clock and observing shadows. • Realized that the earth was CURVED • Celestial navigation • Cartography
17) You should know what seismic surveys are and what they can tell us about sediments
• Conducted frequently in the Gulf of Mexico a ship tows a seismic array. The array has an instrument on it that sends out an explosive burst of air and sends out a loud noise, the rest of the array has a serious of hydrophones that detect the returning echo from the sound pulse - by noting the time difference between different echoes we can make a map of the layers of sediments below this is how potential petroleum deposits are detected.
6) You should have a basic understanding of what oceanographers do, what a career in oceanography is like
• Conducting data and samples at sea o Working at sea can range from deploying small instruments to measure temperature and salinity to deploying large troll nets to catch fish or perhaps installing booies to measure wind speed and wave height • Conducting laboratory experiments to study specific processes o Identifying organisms captured at sea o Using a microscope or working on a computer to enter or analyze data • Create models to simulate physical and biological processes so that we can determine if we actually understand those processes o Use these simulations to possibly make future predictions about things like ocean temperature • Inventors • Servants such as the rush to aid in the deep horizon ocean spill
6) You should know why the continental shelf of the Gulf of Mexico has pits or pockmarks and why these are important
• Continental shelf in the Gulf of Mexico is broad with a large amount of sediment • Located at a passive margin which is typical because they are relatively far away from the plate boundary which is a divergent boundary . • Mississippi river has transported sediment and built up the shelf causing salt deposits from 180 million years ago • The weight of the sediment causes salt domes to rise, spread out, dissolve, and collapse • These formations cause oil and gas to rise up closer to the surface leading to lots of exploration and drilling for oil near the gulf
11) You should know where the thickest sediments are found within the continental margin and which ocean has the thickest sediments and why
• Continental slopes have the thickest sediments • Near the mount of the Mississippi river in the gulf of Mexico and the mouth of the Ganges river in the Indian Ocean • Makes sense because rivers are the most important mode of transport for terrigenous sediments • Thinnest sediment accumulation is near spreading centers like near the Mid Atlantic Ridge
16) You should know what the CCD is and what controls the deposition of calcium carbonate in the oceans
• Depth at which the rate of calcareous sediments supplied to the seabed equals the rate at which they dissolve. • Affects it: increased acidity , pressure, temperature
3) You should know how we discovered the internal structure of the Earth
• Earthquake waves passing through a homogeneous planet meaning that the density of the earth was the same throughout the entire sphere then if an earthquake happened the waves would travel out from the source in very straight lines the speed would never change and you could predict exactly when these waves would arrive at a seismograph at any point on the earth. • If the planet does have a density gradient as ours does then the waves are going to become bent • P waves passing through the earth are bent and there speed was changing as they moved through the earth (there is a solid inner core because the p waves travel just a little faster than if the core was completely solid) • Discovered a shadow zone on one side of the planet opposite of the focal point of earthquakes where s waves are concerned • S waves cannot pass through the liquid outer core o Scientist determined there had to be a liquid outer core to the earth that absorbed the s waves and did not allow them to pass through o This information was confirmed in 1964 with an earthquake in Alaska. The earthquake was so large it could be felt everywhere on the earth. And they were able to use this data to confirm the structure of the earth based on the time of arrival of these different types of waves. o Detailed structure of the earth figure 3.8 in the book WILL BE ON EXAM • Recap: earth has solid inner core and a liquid outter core, we know that because P waves and S waves travel through the earth o The fact that S waves are absorbed and cannot actually travel through the liquid outer core o Different speed in P waves taught us that there is density differences in the earth and there is a solid inner core because the P waves travel a little bit faster than if the core was just liquid
16) You should know how much of the Earth the abyssal plains cover and where in the ocean basins they are located
• Exists between the spreading center and the continental margins • Cover about ¼ of the earth's surface (abyssal plains and hills) • Flat, featureless areas • More common in the Atlantic Ocean • Smooth, even surface due to accumulation of terrestrial sediments o Abyssal hills -small, sediment covered mountains (extinct volcanoes) that have moved away from a spreading center
18) You should know at what type of plate boundary are island arcs formed
• Features of ocean basins also occurring on the edge of the abyssal plains near continental margins • Convergent pate boundaries where trenches form where one plate is subducted under the other • On the coast of south America where we have a trench there is a Collison of an ocean and continent plate so the oceanic plate dives underneath and we get a trench • Island arcs are formed in areas only when TWO ocean plates converge an done plate subducted beneath the other o Islands of japan were formed in this way
8) What is the significance of the Challenger expedition? What was a major finding of the expedition?
• First sailing expedition devoted to science • Proved there was indeed life in the deep sea
8) You should know what authigenic sediments are
• Formed in the same place they now occupy • Minerals expelled at hydrothermal vents that are also found at the same vent site
8) You should know where submarine canyons are located and their orientation relative to the continental shelf
• Generally align at right angles to the shelf edge • Formed by turbidity currents • Submarine canyons cut through continental shelf and slope (EX Hudson canton off of long island New York) o Usually these canyons are adjacent to the mouth of a river o Hypothesized that when sea level was lower the rivers had cut the canyon and now sea level was higher and the canyon was submerged but it was shown that sea level was never low enough to have cut the canyons. o Deep sea fan or alluvial
18) You should know two types of samplers for sediments and what types of samples you can collect with them
• Grab o Grab or clamshell sampler o The instrument is lowered to the bottom in the open position when it hits the bottom it closes and takes a sample of the surface sediments o Used to extensively sample sediments from the bottom • Corer o The instrument is lowered to the bottom (piston corer) it is then drilled into the sediment it then closes and the samples are retrieved bringing back with it stratified core sediments that allows scientist to look at the different sediment layers. • Joint ocean drilling project was formed this project is a global collaboration to obtain cores and then to house them in core libraries. The cores are openly available to any scientist who wants to conduct research on them. The cores can be analyzed at the library of shipped out for analysis.
13) You should know the basic water circulation at hydrothermal vents
• Vents occur where there are fissures in the crust that allow seawater to seep in and be drawn down towards the spreading center. The heat from the magma rising in the spreading center heats the water and it moves back up with minerals dissolved in it from the crust. Specifically, different sulfur compounds. The sulfur compounds support life at these vent systems. • One of the dramatic geological features are black smokers o Chimneys that build up over time as Minerals in the hot water is rising from the bottom build up. Overtime chimneys are formed and the hot water full of minerals continues to escape from the top o Some chimneys can appear white due to different minerals being dissolved in them o Bacteria and organism are thriving
1) You should know how sediments are classified
• Grand Canyon is the southwest United States - many layers of rock in this cross-section, although, at one point all of these layers were sediments that were laid down and compacted and became rock through the process called lithification. o Each layer has characteristics that can tell us about the conditions at the time the sediments were deposited. Many of the rocks at the Grand Canyon were derived from marine sediments because this area was once a shallow sea in the past. o As the Colorado River cut through these layers and formed the Grand Canyon, the different layers were exposed and we could essentially go back in time by examining the increasingly older layers as we move deeper into the Canyon. • Definition of sediments o Particles of organic and inorganic matter that are accumulated in a loose, unconsolidated form o Particles are derived from erosion of rocks, living organisms, volcanic eruptions, and chemical processes o Rates of accumulation vary greatly • Different levels of accumulation o Low sediment accumulation- rocks protruding and a sea anomie is on top of one of the rocks. Near the Mid Atlantic Ridge spreading Center. The crust here is relatively young and there has been little time for sediment to accumulate o High sediment accumulation- adjacent abyssal plain there has been much more time for the sediment to accumulate and smooth out the features. • Current patterns Shape sediment surface o Can be shaped by currents
15) You should know what controls the rate of deposition of oozes
• Higher rates of deposition on the continental shelf than the deep ocean • Higher rates near river mouths (1m every 1000 years) -Estuaries trap sediments and can reduce this rate - Big factor in Louisiana's costal land loss
10) You should know where the Mid-Atlantic ridge intersect land and the characteristics of this area
• Iceland • The Mid-Atlantic Ridge "comes ashore" • Large amounts of thermal and volcanic activity
15) You should know what is significant about the Trieste
• In 1959, Jaques Piccard and US navy Lieutenant Don Walsh became the only humans to descend to the bottom of the Mariana trench • It has been visited twice since that time with ROVs • March 25, 2015 is the only person to solo dive into the Mariana trench o Dive lasted about 7 hours o He collected a lot of interesting footage
1) You should know why the different plates on Earth interact with each other
• In areas where one plate slips below another a subduction zone where the deep earthquakes occur. The west coast of South America is a good example. • The reason plates interact is because the size of the earth is not changing so when plates move, they either .interact (convergent) or new crust is formed (divergent) • At divergent boundaries where plates move apart, magma from the asthenosphere rises and creates new crust • At convergent boundaries where the plates interact either one plate moves under the other plate or the two plates collide and mountains form.
1) You should know the structure of the Earth and be able to point out the aesthenosphere and lithosphere and know their basic properties
• Inner core (dense/solid), outer core (liquid), mantle (liquid), and crust • Denser potions went towards the center so earth became density stratified. • Lower mantle this is the potion of the mantle that extends down to the core and • Asthenosphere and this is a liquid or some might call it plastic and pliable layer of the earth because it is a hot partially melted rock and it is movable and playable • Lithosphere this is the cool rigid outer layer of the earth; the layer in which we live and are the most familiar with. -- The lithosphere (or the crust underneath the ocean) is different in composition then that of the Continents • The crust in the continents is primarily made of Granite and sinks a little bit deeper into the asthenosphere the crust under the ocean is primarily a salt that is cooled lava which is relatively new crust and it tends to ride a little bit higher.
11) You should know the lead scientist who discovered hydrothermal vents
• Jack Corliss, a marine geologist noticed that rocks he was analyzing from the Mid Atlantic Ridge had chemical signatures that indicated that they had been exposed to hot maybe even boiling water. o He then realized that water had to be circulating at these spreading centers and he and fellow scientist Dr. Jack Diamond both postulated the theory that water must be circulating through rocks at spreading centers and the cold ocean water that went in was emerging as heated water around the spreading center. o The theory was good enough to be funded by the national science foundation or NSF o This lead to a cruise, with the research submersfal Alvin to the East Pacific rise. o At the East Pacific rise they found the circulating water that they had expected and also found areas teaming with life around the vents that they had never expected or seen before.
19) You should know what the deepest trench is and how deep it is
• Mariana trench in the Pacific • 11,000 meters deep • Off the coat of guyuam
7) You should know what turbidity currents are
• Occurs when Turbulence mixes sediment from the bottom into the water above a sloping bottom and this now denser mixture is pulled downhill by gravity, cutting the canyon • EX: Denser mixture of water and sediment that is traveling down the sloping bottom. • Turbidity currents can be super powerful especially when moving down a steeper slope
6) You should know where some of the oldest oceanic crust is and how old it is
• Older crust is at a greater distance from the spreading center. But the oldest crust oceanic crust be approximately 160 - 180 million years old • Near subduction zones, the oldest is in the western Pacific near Japan. It is the farthest distance from a spreading center
19) You should know where the oldest sediments are, how old they are, and why there are no older sediments
• Oldest sediments 180 million years old • This is because the oldest oceanic crust on earth is 180 million years old • While there have been continental and oceanic plates since the earth cooled and the lithosphere formed, due to tectonic plates the plates are constantly being moved at spreading centers and recycled at subduction zones. • Oldest oceanic crust is in the western pacific this is because the spreading center where this is formed, the East pacific rise in south America, is incredibly far away
4) You should know the three major oceans and how they are related in terms of size
• Pacific - largest ocean both in terms of surface area and amount of water. It's over twice as large as the Atlantic ocean and the Indian ocean and also has the greatest mean depth and contains some of the deepest areas of the world's oceans • Atlantic and Indian - similar in size and volume and have a similar mean depth
4) You should know how the Earth, moon, and oceans formed
• Scientist have used scientific method to state testable hypothesis based on observations of the earth and the solar systems • These hypothesis have been supported by further observations and experiments, but much work remains to explain all the details of the formation of the Earth o The earth formed as particles congregated together, as the earth grew in size the force of gravity began to compress it and over time denser material like iron moved to the center and lighter materials like silica moved to the outer layers o The Moon was formed when a smaller planetary body (about the size of mars) hit the earth. Rocky debris from the impact was thrown out and formed a ring around the earth. This material eventually condensed together over time and formed the moon. o The oceans formed when water vapor from the erupting volcanos condensed, fell as rain, and gradually filled the ocean basins -- 100% of the surface of the earth may have been covered by the oceans at one time, no one knows for sure.
11) What are the major US oceanographic institutions?
• Scripps 1903 • Woods Hole 1930 • University of Washington 1930, 1951 • Lamont-Dohtery 1950s • COAS, Oregon State 1959
10) You should know what pelagic and nertitic sediments are and where they are located
• Sediment distribution (see below) o Clay is the dominant sediment type in most of the open ocean -38 percent of the deep seabed is covered by clays - Average rate of accumulation is 2 mm every 1000 years (slows) -Terrigenous sediments • Neritic sediments o Overlay continental margins o Mostly terrigenous o There also biogenesis sediments as these are areas of high pelagic production o Larger particle size deposited nearshore (sand) o Smaller particle size deposited offshore (silts and clays) o Ice shelves and icebergs and turbidity currents can disrupt this sorting pattern. Ice shelves and ice bergs: sediments of larger particle size can be deposited on the ice. The ice can then extend out from the continent or float away. As the ice melts the sediment can be deposited this can lead to sediments with larger particles to be laid down offshore where they would not normally be transported o Historical changes in sea level are evident in these sediment records. -for example: if sea level was higher than present we may see sediments with a larger grain size • Pelagic sediments o Overlay the continental slope, rise, and deep-ocean basin o High proportion of biogenesis sediments than neritic sediments, but still the majority of the volume are terrigenous sediments o Sediments of the slope, rise, and deep-ocean floor o Thickness is highly variable -thickness on the abyssal plains and thinnest on the ridges o Average thickness in the Atlantic is greater than the Pacific -more rivers feed the Atlantic -The Atlantic is geographically smaller -Specific has more subduction zones
12) You should know what the process of lithification is
• Sediments are converted into sedimentary rock by pressure - induced compaction or cementation • These formations can be lifted above sea level through the action of plate tectonics o Mt. Everest o Colorado plateau
2) You should know the difference between a testable and untestable hypothesis
• Testable - must have the ability to find an answer that will support it or disprove it not just one of those two options. • Untestable - cannot be used to learn anything about the world. "somewhere"
9) You should be able to define paleomagnetism and briefly describe how it has been used to determine the rate of seafloor spreading
• The 'fossil' magnetic field frozen in cooled magma that shows the polarity of the Earth at the time the rock was formed by examining the direction the magnetite is aligned. We use it to calculate the rate of spreading at divergent boundaries Paleomagnetism- is the study of the record of the earth's magnetic field in rocks, sediment, or archeological materials. o The earth's magnetic field is caused by movement of molten metal in the outer core- this field reverses every few hundred years. o Iron bearing minerals (magnetite) will align themselves along the lines of magnetic force o As molten magma cools, the magnetite's align themselves in the direction of the magnetic field o The alignment will not change and becomes a "fossil" of the magnetic field known as Paleomagnetism. o Surveys to measure the magnetic field on either side of the spreading center like the Mid Atlantic Ridge revealed bands of a salt that we term having a normal magnetic field because they match the magnetic field of the earth today. The alternating bands with a reversed magnetic field are shown in color. o By dating the rocks in the different bands we can determine when they were formed o Because we know the time that the earth's polarity changed (when the north and south poles became reversed referring to their magnetic fields) we can use this information along with how wide these alternating bands are and calculate the rate of spreading.
4) You should know why divergent boundaries are offset by transform faults
• The axis of spreading cannot occur in a straight line on a curved surface and a fault forms where two plates move past each other • The Mid Atlantic ridge is broken periodically by transform faults this happens because the earth is curved.
5) You should know what dictates how dense a plate is and how the density of the plates that interact determines what the outcome is
• The denser oceanic plate is subducted below the continental plate, a trench forms and there are deep earthquakes as the plate subsides. The partial melting of the plate in the asthenosphere causes magma to ride and volcanoes sometimes form on the continental plate. This is occurring off the west coast of south America • The plate that is denser is subducted, this will be the older plate. Because it has had more time to cool, it is denser than a younger warmer plate. EX: convergent boundary near Japan • It's temperature. Older plates are cooler and denser than younger, warmer plates
3) You should know how size affects settling rate
• The smaller the particle the smaller the settling rate and the longer it will take for the particles to sink to the bottom. Important because it dictates how sediments are deposited and re-suspended in the water column. • Decrease in steam velocity from larger to smaller particles • For any particles larger than sand the settling velocity is very fast and not reported • Stream velocity- how fast the water is moving. This erodes the particle and brings it out sediment and into the water column. The particle can then be transported as long as stream velocity remains above some minimal level • Increase from sand to clay because although clay particles are smaller, they can pack together more tightly and it requires more energy to initially erode them and bring them into the water column.
7) You should know how sediments are classified based on sorting and under what conditions we find these different classes of sediments
• Well sorted sediments o Sediments composed primarily of particles of one size o Found where energy fluctuation occurs in a narrow range • Poorly sorted sediments o Sediments composed of particles of a range of sizes o Found where energy fluctuations occur over a wide range
17) You should know the characteristics of the bathymetry of the abyssal plains
• between ridge systems and continental margins • They are generally smooth and featureless due to the accumulation of sediments
