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Oceanography > Exam #1 > Flashcards

Exam #1 Flashcards

1
Q

What makes a molecule

A

atom + atom

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2
Q

What is an ionic bond? Give an example

A

an atom donates 1 (or more) electron to another element with an incomplete outer shell, held together electrostatically

Example: sodium atom donates to chlorine

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3
Q

Covalent bond, give an example

A

bond of sharing electrons

Example: Water; oxygen atom has 6 electrons & lacks 2, H atom lacks another so they’re attracted to eachother

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4
Q

What is another name for water?

A

“universal solvent”

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5
Q

What is cohesion?

A

water’s exceptional ability to stick to itself

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6
Q

What is the surface tension of water?

A

the property of a water surface that allows it to resist external forces due to the strong attraction between water molecules

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7
Q

What is polarity?

A

The unequal sharing of electrons

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8
Q

How does polarity affect water?

A

high surface tension, cohesion, and its ability to dissolve many substances

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9
Q

Polarity -> hydrogen bonds..how?

A

polarity makes water molecules attract each other due to the slightly positive charge on the hydrogen atoms and the slightly negative charge on the oxygen atom, allowing water to form hydrogen bond

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10
Q

Explain hydration process

A

basically the pulling of a substance’s molecules apart and then surrounding them with water (dissolving)

electrostatic attraction is greatly reduced

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11
Q

What is the mean salinity of seawater?

A

35
35 PSU
or 35 ‘per mil’

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12
Q

What is the modern way of measuring salinity? How does it work?

A

electrical conductivity

is the comparison of the conductivity of two solutions:
1. seawater
2. standard concentration of potassium chloride

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13
Q

What does PSU stand for

A

practical salinity units!

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14
Q

What are some major components of salinity?

A

chlorine, sodium, magnesium, sulfur, calcium, potassium

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15
Q

What is the seawater pH buffer?

A

7.5 to 8.1

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16
Q

How does pH change with depth? and why?

A

It decreases (becomes more acidic) with depth
1. as you go deeper, concentrations of dissolved carbon dioxide increases (due to respiration of marine orgs)
2. reacts with water to form carbonic acid
3. this lowers pH, making water MORE acidic

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17
Q

What is the pH of seawater?

A

8.1

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18
Q

What are the 2 most important influences on density? Why more than the 3rd?

A

2 most important = temperature & salinity

pressure is not as important because liquid is virtually incompressible

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19
Q

What is a halocline? Where in the ocean is salinity relatively the same?

A

rapid change in surface water salinity

when greater than 100m deep, salinity

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20
Q

What is the difference in density from shallow to deep water?

A

2%

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21
Q

density _______ as temperature _______ for pure water (0 to 4 degrees Celcius)

A

increases; increases

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22
Q

(normal behavior) density _______ as temperature __________ from 4 to 100 degrees Celcius

A

decreases; increases

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23
Q

Why is iron important in the ocean

A

vital nutrient for phytoplankton

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24
Q

What is plate tectonics?

A

theory explaining earth’s crust; rigid lithospheric plates which move slowly over the underlying mantle

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25
Q

Who is Alfred Wegner? What did he discover/using what discovery?

A

He used evidence from Atlantic geology to discover Pangaea

26
Q

What 3 things did Wegner use to theorize Pangaea?

A
  1. matching rock sequence
  2. glacial deposits in the tropics
  3. continents fit together (not perfect fit, however, due to erosion and deposition over 200 mil years ago)
27
Q

what is Isostasy

A

lithospheric plates float on the asthenosphere at different levels, determined by density

28
Q

What are some characteristics of oceanic crust? Compared to continental?

A

consists of cooled magma, silicon, aluminium oxide, made primarily of gabbro/basalt

oceanic crust is generally thinner than continental

29
Q

What are some characteristics of continental crust? Compared to oceanic?

A

cooled magma, mainly grantie

generally thicker than oceanic

30
Q

What does plate tectonics explain?

A

how and why lithospheric plates move

31
Q

What is the driving force behind the movement of tectonic plates?

A

heat energy transferred through convection

32
Q

Where does downwelling occur?

A

in the mantle beneath deep ocean trenches

33
Q

What is a superplume?

A

large area of the mantle that “swell” up

34
Q

What is created & what happens at an oceanic/oceanic convergent boundary? Give an example

A

Created: island arcs, trenches
Happens: subduction zones, the denser oceanic plate will be pushed under

Example: Aleutian/Indonesian island arcs

35
Q

What is created & what happens at an oceanic/continental convergent boundary? Give an example

A

Created: continental crust
Happens: subduction zone; the oceanic (denser) plate subducts under continental

Example: Pacific Coast of U.S.A

36
Q

What is created & what happens at an continental/continental convergent boundary? Give an example

A

Created: Mountain ranges
Happens: NOTHING HAPPENS!! no subduction (earthquakes though)

Example: Himalayas

37
Q

How many major tectonic plates are there?

A

7

38
Q

What is created at transform faults? Give an example

A

earthquakes, faults, sometimes low hills/mountains

Example: San Andreas Fault

39
Q

What is created at divergent boundaries?

A

Oceanic ridge & Rift zone

40
Q

What plates form oceanic ridges? What causes this movement/in response to what?

A

Oceanic/Oceanic plates

It’s a divergent movement in response to subduction at other boundaries

41
Q

Put in order the landmarks starting at continental shelf –> abyssal plain

A
  1. continental shelf
  2. shelf break
  3. continental slope
  4. Trench
  5. Abyssal plain
42
Q

What is a hotspot/how is it formed?

A

area wheere heat from mantle flows outward through crust @ higher rates than in surrounding crusts

43
Q

Where do most hot spots form? (hint: beneath what) Give an example

A

beneath ocean

Hawaiin islands

44
Q

What does paleomagnetism explain? How?

A

it helps explain the abrupt change in the Pacific plate’s direction of motion

  1. examining the cores to determine paleolatitude
  2. dip angle: scientists know the magnetic field is NOT parallel, but that the compass points toward the group
44
Q

How are hotspot trails created

A
  1. lithospheric plate moves over an oceanic hotspot
  2. the most recently fomred volcanic island moves AWAY from the hot spot
  3. eventually, plates move again and new islands.. = island TRAILS (and seamounts)
44
Q

What the sigma is a seamount

A

underwater mountain.. duh

44
Q

ok what is paleomagnetism

A

study of the earth’s old magnetic field which changes direction each 450,000

45
Q

Name some difficulties of studing the ocean

A

“seeing” through ocean water, pressure, inacessibility, conductivity, corrosion, and fouling, wave motion, logistics

46
Q

on what voyage did scientists realize there was much more ocean to study?

A

The Challenger

47
Q

What is bathymetry?

A

The measure the ocean’s depth

48
Q

What are the different ways bathymetry has been measured? briefly describe them

A
  1. Soundings: (outdated, ineffective) weight attached to wire & dragged along bottom
    2.Echo sounders: started being used following the Titantic, utilized sonar if temperature & salinity were known
    3.Wide Area Echo Sounders (Multi-beam): 200+ sonar beams undership
  2. Satellites: cover lots of area, low resolution
49
Q

what is the USS San Francisco?

A

(unfortunately) gave us a reason to study ocean floor topography

it crashed into “uncharted” seamount in 2005 (1 death & 98 injured)

50
Q

What did the OG sounding use for units of measure?

A

fathoms (exactly 6 foot measurements)

51
Q

What are grab samplers? describe

A

clamshell method to collect sediments

partially mixes/disturbs layers

52
Q

What are box corers?

A

method to collect sediments

minimizes mixing of sediment layers, difficult to deploy b/c heavy

53
Q

What are gravity & piston corers?

A

Gravity: freefall from cable, weighted core tube
Piston:longer core can be obtained, minimizing vertical distortion

54
Q

What are drilling ships? Give an example

A

method of collecting sediments

Glomar Challenger (1968) which helped confirm theories of seafloor spreading & continental drift -> JOIDES Resolution -> Chikyu

55
Q

What is a CTD package?

A

Used to determine conductivity, temperature, and depth of water

that big swinging thing off boats that people have gotten hurt by

56
Q

What are 2 we can measure currents?

A

speed & direction can be computed if you have salinity and temperature

Chemical/radioactive tracers can be dissolved in water

57
Q
A

Oceanography (2 decks)

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