FINALIZED
MIDTERM II STUDY GUIDE
GEOL 1080 INTRODUCTION TO OCEANOGRAPHY
FALL 2010
READ THIS FIRST: this study guide has been updated. A significant number of study questions have been added. I’m sorry if it’s a
burden that questions have been added, but I promise that knowing them will help you do well on the exam. The outline below
is not meant to be fully comprehensive. This lists all the major topics we discussed in class, but it does not completely cover
everything involved with every topic, so use this as a guide to your notes, and to what to look at in the text.
WHAT THE EXAM WILL COVER: The exam will focus on details of plate tectonics that we covered just before and after the first
midterm, marine provinces, marine sediments a few questions on atoms that relate to chapter 5 (there are no questions on
salinity, properties of water, etc. from chapter 5), and some basic information on hurricanes is fair game as well. You will be
responsible for the corresponding chapters from your textbook (Chs. 2 thru 5). Please be aware that the exam does include
some simple calculation(s).
WHEN THE EXAM WILL TAKE PLACE: The exam will be available in the CTC from Monday 10/25 through Wednesday 10/27.
Wednesday will be a late day with the commensurate $3 charge. You must take the exam during the scheduled time at the CTC
unless you have made other arrangements with Prof. Bunds.
INSURANCE: Insurance is due Wednesday 10/27. To be eligible for insurance points you must submit insurance to Prof. Bunds or
the College of Science and Health main office (one of the secretaries will put it in Prof. Bunds’ mailbox) by 3 pm Weds. 10/27.
Make yourself a photocopy of your insurance work and be sure to follow the directions to ensure you get full credit.
HANDOUTS: Where to find study guides and handouts on the web: http://research.uvu.edu/bunds
1. Marine Provinces – The oceans can be divided into provinces based on ocean depth and proximity to a continent. The major
provinces are continental margins, deep-ocean basins and mid-ocean ridges
a. First: Bathymetry – depth + measurement (of seafloor) – the depth of the seafloor
i. Old method of determining bathymetry was sounding
1) HMS Challenger did first systematic soundings – 492 around the globe during a 3.5 year voyage around 1872.
Showed that seafloor is not flat.
ii. Sonic techniques. Precise techniques and widespread use of the method in 1960’s allowed compilation of quality
bathymetric maps at that time. Side-scan sonar allows mapping of wide swaths with a single pass. Still making
detailed seafloor maps.
iii. Harry Hess. Geologist and Navy officer, collected sonar information from ship he commanded in WWII Pacific
Theater, which led to his discovery of guyots (tablemounts) and mid-ocean ridges. He is the originator of the sea-floor
spreading concept.
b. Continental margins – a continental margin is the edge of a continent; the transition from continent to ocean. There are two
types - passive and active
i. Passive – Passive margins are imbedded within the interior of a lithospheric plate; no active plate boundary exist along
the continental margin. This is an important point: many continental margins do not coincide with a plate boundary.
1) Consist of shelf, shelf break, slope and rise
a) Shelf – essentially flooded continent. Shallow water, and only very gently sloping
b) Break – boundary between shelf and slope; ‘break in slope’
c) Slope – relatively steeply sloped; ‘edge’ of continent
d) Rise – gently sloped area oceanward os slope; on oceanic crust; created by sediment that has slid off the
continent(mostly left by turbidity currents)
2) East coast of U.S. is a prime example of a passive margin.
ii. Active – Occur where a plate boundary coincides with a continental margin.
1) two types – convergent and transform.
2) West coast of Americas is example
3) Active margins consist of a narrow shelf, steep slope, and a trench if there is a subduction zone
iii. Submarine canyons and turbidity currents.
c. Deep Ocean Basins - beyond (oceanward) the continental rise. Three main subzones – abyssal plains, volcanic peaks,
trenches
i. Abyssal Plains, know where they are, why they are flat plains, and how deep they are on average.
ii. Abyssal Hill Regions – similar to abyssal plains but thin sediment, and thus dominated by abyssal hills. Pacific.
iii. Trenches. Deep, linear troughs along convergent plate margins (with oceanic lithosphere).
GEOL 1080, Introduction to Oceanography, Midterm II Study Guide, Fall 2010, M. Bunds Instructor
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Trench
Average width [km]
Depth [km]
Slope [degrees]
Length [km]
Aleutian
50
7.7
17.1
3700
Peru – Chile
100
8
9.1
5900
Japan
100
8.4
9.5
800
Philippine
60
10.5
19.3
1400
Mariana
70
11
17.4
2550
d. Mid-ocean Ridges; where, what, how deep. Know names of some segments
i. Pillow basalts
ii. Hydrothermal vents (e.g., black smokers)
iii. Ridge is cut by transform faults and fracture zones.
2. Marine Sediments
a. Why study seafloor sediments?
i. Hydrocarbons, Past climate – key to current, future climate trends, Sealife – past and present, Pollution, Study Earth’s
geologic system – where sediment goes; analogs for ancient sediments found on land today, etc., mineral resources,
curiosity
b. Sources of information on seafloor sediments
i. Dredging – big shovel,
ii. Gravity coring.
iii. Drilling. Fancy oil techniques. Expensive, but goes deep and can produce excellent intact samples
1) Deep sea drilling history: JOIDES – U.S. funded concerted effort to sample seafloor; 1963, DSDP – beginning of
actual concerted drilling; started in 1968, built the Glomar Challenger (could drill in 6000 m of water; documented
several key aspects of plate tectonics and seafloor spreading). Project became international in 1975 (W. Germany,
Japan, UK and USSR). Became ODP in 1983, with 20 participating countries. Ongoing.
iv. Seismic techniques, primarily of the type discussed earlier. Basic idea of the technique is to bounce or echo sound off
of the layers of sediment beneath the seafloor. This method is widely used, especially in the oil industry because it
provides information on broad areas of the seafloor, as opposed to drilling which only provides data on at a single spot.
c. What are sediments?
i. Material that has settled – in this case to bottom of seafloor
ii. Bits of rock (lithogenous) and organisms (biogenous) primarily. Some can be ‘chemical’ – precipitate from water
(hydrogenous). Get a mixture of lithogenous and biogenous pretty much everywhere – although often one dominates.
iii. Sediment can become lithified into sedimentary rock over time – usually with burial by more layers of sediment.
d. Where are sediments in the oceans? Can be grouped into those
i. close to the continents (Neritic deposits).
ii. deep ocean, relatively far from continents (Pelagic deposits)
e. Lithogenous sediment
i. Derived from mechanical weathering of rocks on continents.
ii. Much is transported long distances by rivers. Some by wind, glaciers. Wind gets very small particles of lithogenous
sediment to deep ocean areas.
iii. Distributed along and away from coasts by strong beach currents and turbidity currents.
iv. Tend to be rich in quartz because it is resistant to weathering and dissolution; most other minerals get dissolved before
they make it to the ocean.
v. Maturity. Rounding, sorting, quartz content.
vi. Lithogenous sediment dominates most neritic deposits, of which there are several types.
1) Beach. Consists of whatever is available. If there is a large river nearby, often has nice quartz-rich sand. Other
places its bare rock or gravel. Material is transported and weathered by waves, especially during storms.
2) Shelf deposits. Upper layers mostly left by rivers when sealevel was lower during last ice age. Sands, muds.
Layers underneath left in ocean tend to get finer-grained with distance from shore. Fine grained material is unable
to settle out of water where waves move water. Glacial deposits in some high latitude places.
3) Continental rise – formed by deposits from turbidity currents as discussed earlier. Graded bedding deposits –
coarse sands to muds.
4) Pelagic / Deep ocean –
a) Mostly very fine grained (clay sized) particles transported over ocean by winds. Called abyssal clay.
b) Deep ocean currents apparently do not transport much if any sediment.
c) In places there is some glacial material that has been dropped by icebergs, which are pieces of glaciers.
Process is called ice rafting, and cobbles and boulders left in deep ocean in this way are called ‘dropstones.’
5) Lithogenous sediment does not dominate over biogenous sediment in much of the deep oceans.
GEOL 1080, Introduction to Oceanography, Midterm II Study Guide, Fall 2010, M. Bunds Instructor
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f. Biogenous Sediment. From organisms. Macroscopic or microscopic; nearly all from microscopic
i. Two main types of microscopic – siliceous and calcareous. See handout
ii. Siliceous biogenous sediment consists of plankton tests (shells) made of silica (SiO2); zooplanktonic (Radiolarians)
and phytoplanktonic (diatoms) are the two main types of plankton that make silicic tests [know what both
zooplankton and phytoplankton are]. Oceans dissolve silica but only very slowly, so layers of sediment that consist
primarily of siliceous tests (siliceous oozes) can and do form where the productivity of radiolarians and/or diatoms is
great enough. Mass of all diatoms in the oceans probably equals or exceeds mass of all other organisms on Earth
combined! Siliceous plankton thrive in cold climates at high latitudes.
iii. Calcareous – tests made of calcite (CaCO3); zooplanktonic (foraminifera) and phytoplanktonic
(coccolithosphores). Oceans dissolve calcite below the calcite compensation depth (CCD – know about the CCD!!).
So calcareous oozes can only accumulate where oceans are shallower than CCD – primarily at the ridges. However,
calcareous oozes can be preserved as the seafloor ages and sinks below CCD if calcareous ooze is sealed from ocean
by more sediment (siliceous or lithogenous). Calcareous plankton thrive in warm climates – low latitudes.
iv. Uses of oozes: diatomaceous earth is used for filtration, as an abrasive, to absorb chemical spills and in chemistry.
Calcareous oozes are sources of chalk.
g. Hydrogenous sediment – sediment that precipitates from water. Examples are some limestones (only abundant type of rock
formed this way), manganese nodules and phosphates (both potentially important ores - someday).
h. Distribution of sediments and rates of sedimentation on seafloor
i. See table 4-4;
Sediment type and environment
Average deposition rate
Coarse lithogenous sediment – necrotic
environment
1 meter per thousand years
Biogenous ooze, pelagic environment
1 centimeter per thousand years
Abyssal clay (windblown lithogenous
sediment) – pelagic environment
1 millimeter per thousand years
ii. See figures 4-16; 4-17; 4-18; 4-19
iii. Global thickness of sediments– thickest near continents, on older seafloor. (Neritic deposits)
iv. Lithogenous sediments dominate near continents
v. Calcareous oozes tend to dominate on ridges, especially at low (warm) latitudes.
vi. Siliceous oozes tend to dominate in deep ocean
3. Seawater!
a. Atoms are the smallest particles that retain the characteristics of specific elements. They consist of:
i. Nucleus:
1) protons (+) charge, mass (of ‘1’)
2) Neutrons, no charge, mass (of ‘1’).
ii. Electrons: (-) charge (equal but opposite to proton), almost no mass. Electrons orbit around the nucleus in shells. It is
energetically favored for atoms to have full outer shells.
iii. In its neutral state an atom has the same number of electrons as protons and thus no net charge. If an atom obtains an
extra electron, the atom has net negative charge; if and atom gives up an electron, it will have a net positive charge.
Atoms not in base state are called ions
iv. bonding: atomic bonding results from interactions between electrons of neighboring atoms. The electrons interact
because it is energetically favored for atoms to have full outer shells. Consequently, atoms can give away or take
electrons and then bond because of their resulting net charges (ionic bonding), or because atoms share electron(s) to
produce a single full shell that surrounds both atoms (covalent bonding).
b. Elements
i. Atoms naturally come in 92 main varieties. These are the naturally occurring elements. The difference between atoms
of different elements is the number of protons in the nucleus. The number of electrons or neutrons in atoms of the
same element can vary. E.g., all Carbon atoms have 6 protons, but some have 6 neutrons, a few have 7, and a very few
have 8 (these are the three isotopes of carbon). Similarly, the number of electrons varies, and in fact the same atom can
give up and take electrons easily and repeatedly. The number of protons is the basic control on the chemical and
physical behavior of an atom.
4. Simple calculations
a. Surface area (SA) to volume (V) ratio (SA/V) of a sphere. This calculation reveals the very large ratio of surface area to
volume (SA/V) that tiny plankton have, which helps them ‘float’ near the ocean surface where sunlight and prey are
available.
i. Surface area of a sphere: The formula is 4 x π x r2 , where pi = 3.14 and r is the radius of the sphere.
ii. Volume of a sphere: The formula is 4/3 x π x r3 , where pi = 3.14 and r is the radius of the sphere.
iii. Be careful as to what units you use.
GEOL 1080, Introduction to Oceanography, Midterm II Study Guide, Fall 2010, M. Bunds Instructor
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iv. Examples
1) Sphere of radius 1 meter (1 meter = 39 inches):
a) SA = 4 x 3.14 x 12 = 12.6 m2
b) V = 4/3 x 3.14 x 13 = 4.2 m3
c) SA/V = (12.6 m2)/(4.2 m3) = 3 m-1
2) Sphere representing a small plankton, radius 10 microns (10 millions of a meter)
a) SA = 4 x 3.14 x 0.000012 = 1.26x10-9 m2 = 0.00000000126 m2
b) V = 4/3 x 3.14 x 0.000013 = 4.2x10-15 m3 = 0.0000000000000042 m3
c) SA/V = (1.26 x 10-9 m2)/(4.2 x 10-15 m3) = 3 x 105 m-1 = 300000 m-1
3) The significance is that the ratio of surface area to volume for a small plankton is 300,000 times greater than for a
sphere 1 meter in diameter (which might represent, say, a seal). Because surface area creates friction when
moving (i.e., sinking) through water, the plankton will have far greater resistance to sinking relative to its weight
(which is proportional to its volume) than a larger organism, which helps prevent it from sinking. On the other
hand, heat is lost through surface area, so a larger organism will lose heat much more slowly to surrounding
seawater than a small orgranism.
Second, here are some study questions.
If you want to turn these in as part of you r insurance work, be sure to answer them with complete sentences on separate
sheets of paper and staple everything together! Note that to earn insurance credit, you must do these questions and the questions
from the ends of the chapters listed on the syllabus for the chapters covered by this exam (see top of study guide for which chapters
are covered by the exam).
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34.
Explain why the oceans contain ridges.
Who was Harry Hess? What did he do, and what did he discover?
What was the Trieste, and what did people do in it?
What and where are the major marine provinces?
Draw a side view of a continental margin. In your sketch include and label the shelf, shelf break, slope and rise.
Explain what a continental margin is.
Briefly explain the difference between a passive and an active continental margin. Give at least one example of each.
How does the continental rise form?
How can one tell that ancient sedimentary rock layers may have been deposited by turbidity currents?
How do submarine canyons form? Are they common in the ocean?
What are abyssal plains, where are they, how do they form, and why do they tend to exist in some oceans but not others?
Why, in some parts of the oceans, are there abyssal hill provinces instead of abyssal plains?
What are typical depths of abyssal plains, deep sea trenches, mid ocean ridges, and continental shelves? How wide are
trenches?
Briefly explain standard sonar and side-scan sonar techniques, and their use and importance to oceanography.
Explain what seamount and tablemounts are, as well as how they form.
Explain what atolls are and how they form.
What are the two main types of sediment in the oceans, and what is the origin of the material in each type?
From where does most lithogenous marine sediment come, and how does it get to the oceans?
Why is quartz an abundant mineral in lithogenous sediment?
What is the most abundant type of life on Earth?
What is the CCD, where is it, and why does it exist?
Do calcareous oozes exist below the CCD, and if so why?
Which type of biogenic ooze can accumulate in the deep ocean?
List three industrial/human uses of diatomaceous Earth.
On average, how fast do biogenic oozes accumulate on the seafloor?
On average, how fast does lithogenous sediment accumulate on the continental shelf?
What is meant by the terms neritic and pelagic?
How does most lithogenous sediment get to the deep oceans in neritic environments?
Is there lithogenous sediment in the pelagic environment, and if so how does it get there, and what is its grain size?
What does zooplankton mean? Name a calcareous and a siliceous zooplankton.
What does phytoplankton mean? Name a calcareous and a siliceous phytoplankton.
What types of sedimentary rock result from siliceous oozes?
What types of sedimentary rock result from calcareous oozes?
What is the difference between sediment and sedimentary rock?
GEOL 1080, Introduction to Oceanography, Midterm II Study Guide, Fall 2010, M. Bunds Instructor
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35. Explain how sedimentation processes and the types (and amounts) of sediment formed differ between continental margin and
deep ocean areas. What do we call the areas near continental margins and deep ocean?
36. In relation to continental margins and the deep ocean, where is oil found (and where has it formed in the past)?
37. Explain the components of atoms and their important properties (i.e., mass and electric charge).
38. How do the atoms of different elements differ from each other?
39. Can the number of electrons in a Carbon atom vary?
40. Do all Carbon atoms have the same number of neutrons?
41. On what basis are hurricanes categorized (i.e., as a 1, 2, 3, 4, or 5)? Be specific in regards to how wind speed factors into the
categorization system.
42. Compare typhoons, cyclones and hurricanes.
43. Calculate the surface area (SA), volume (V) and surface area to volume ratio (SA/V) for a sphere of radius 2 meters.
44. Explain the importance of SA/V to microscopic marine plankton and marine mammals. In your explanation, include the
relative values of SA/V for the organisms, and how their SA/V benefits them.
45. How old is the Earth?
GEOL 1080, Introduction to Oceanography, Midterm II Study Guide, Fall 2010, M. Bunds Instructor
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