Exam #1 Flashcards
What makes a molecule
atom + atom
What is an ionic bond? Give an example
an atom donates 1 (or more) electron to another element with an incomplete outer shell, held together electrostatically
Example: sodium atom donates to chlorine
Covalent bond, give an example
bond of sharing electrons
Example: Water; oxygen atom has 6 electrons & lacks 2, H atom lacks another so they’re attracted to eachother
What is another name for water?
“universal solvent”
What is cohesion?
water’s exceptional ability to stick to itself
What is the surface tension of water?
the property of a water surface that allows it to resist external forces due to the strong attraction between water molecules
What is polarity?
The unequal sharing of electrons
How does polarity affect water?
high surface tension, cohesion, and its ability to dissolve many substances
Polarity -> hydrogen bonds..how?
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
Explain hydration process
basically the pulling of a substance’s molecules apart and then surrounding them with water (dissolving)
electrostatic attraction is greatly reduced
What is the mean salinity of seawater?
35
35 PSU
or 35 ‘per mil’
What is the modern way of measuring salinity? How does it work?
electrical conductivity
is the comparison of the conductivity of two solutions:
1. seawater
2. standard concentration of potassium chloride
What does PSU stand for
practical salinity units!
What are some major components of salinity?
chlorine, sodium, magnesium, sulfur, calcium, potassium
What is the seawater pH buffer?
7.5 to 8.1
How does pH change with depth? and why?
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
What is the pH of seawater?
8.1
What are the 2 most important influences on density? Why more than the 3rd?
2 most important = temperature & salinity
pressure is not as important because liquid is virtually incompressible
What is a halocline? Where in the ocean is salinity relatively the same?
rapid change in surface water salinity
when greater than 100m deep, salinity
What is the difference in density from shallow to deep water?
2%
density _______ as temperature _______ for pure water (0 to 4 degrees Celcius)
increases; increases
(normal behavior) density _______ as temperature __________ from 4 to 100 degrees Celcius
decreases; increases
Why is iron important in the ocean
vital nutrient for phytoplankton
What is plate tectonics?
theory explaining earth’s crust; rigid lithospheric plates which move slowly over the underlying mantle
Who is Alfred Wegner? What did he discover/using what discovery?
He used evidence from Atlantic geology to discover Pangaea
What 3 things did Wegner use to theorize Pangaea?
- matching rock sequence
- glacial deposits in the tropics
- continents fit together (not perfect fit, however, due to erosion and deposition over 200 mil years ago)
what is Isostasy
lithospheric plates float on the asthenosphere at different levels, determined by density
What are some characteristics of oceanic crust? Compared to continental?
consists of cooled magma, silicon, aluminium oxide, made primarily of gabbro/basalt
oceanic crust is generally thinner than continental
What are some characteristics of continental crust? Compared to oceanic?
cooled magma, mainly grantie
generally thicker than oceanic
What does plate tectonics explain?
how and why lithospheric plates move
What is the driving force behind the movement of tectonic plates?
heat energy transferred through convection
Where does downwelling occur?
in the mantle beneath deep ocean trenches
What is a superplume?
large area of the mantle that “swell” up
What is created & what happens at an oceanic/oceanic convergent boundary? Give an example
Created: island arcs, trenches
Happens: subduction zones, the denser oceanic plate will be pushed under
Example: Aleutian/Indonesian island arcs
What is created & what happens at an oceanic/continental convergent boundary? Give an example
Created: continental crust
Happens: subduction zone; the oceanic (denser) plate subducts under continental
Example: Pacific Coast of U.S.A
What is created & what happens at an continental/continental convergent boundary? Give an example
Created: Mountain ranges
Happens: NOTHING HAPPENS!! no subduction (earthquakes though)
Example: Himalayas
How many major tectonic plates are there?
7
What is created at transform faults? Give an example
earthquakes, faults, sometimes low hills/mountains
Example: San Andreas Fault
What is created at divergent boundaries?
Oceanic ridge & Rift zone
What plates form oceanic ridges? What causes this movement/in response to what?
Oceanic/Oceanic plates
It’s a divergent movement in response to subduction at other boundaries
Put in order the landmarks starting at continental shelf –> abyssal plain
- continental shelf
- shelf break
- continental slope
- Trench
- Abyssal plain
What is a hotspot/how is it formed?
area wheere heat from mantle flows outward through crust @ higher rates than in surrounding crusts
Where do most hot spots form? (hint: beneath what) Give an example
beneath ocean
Hawaiin islands
What does paleomagnetism explain? How?
it helps explain the abrupt change in the Pacific plate’s direction of motion
- examining the cores to determine paleolatitude
- dip angle: scientists know the magnetic field is NOT parallel, but that the compass points toward the group
How are hotspot trails created
- lithospheric plate moves over an oceanic hotspot
- the most recently fomred volcanic island moves AWAY from the hot spot
- eventually, plates move again and new islands.. = island TRAILS (and seamounts)
What the sigma is a seamount
underwater mountain.. duh
ok what is paleomagnetism
study of the earth’s old magnetic field which changes direction each 450,000
Name some difficulties of studing the ocean
“seeing” through ocean water, pressure, inacessibility, conductivity, corrosion, and fouling, wave motion, logistics
on what voyage did scientists realize there was much more ocean to study?
The Challenger
What is bathymetry?
The measure the ocean’s depth
What are the different ways bathymetry has been measured? briefly describe them
- 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 - Satellites: cover lots of area, low resolution
what is the USS San Francisco?
(unfortunately) gave us a reason to study ocean floor topography
it crashed into “uncharted” seamount in 2005 (1 death & 98 injured)
What did the OG sounding use for units of measure?
fathoms (exactly 6 foot measurements)
What are grab samplers? describe
clamshell method to collect sediments
partially mixes/disturbs layers
What are box corers?
method to collect sediments
minimizes mixing of sediment layers, difficult to deploy b/c heavy
What are gravity & piston corers?
Gravity: freefall from cable, weighted core tube
Piston:longer core can be obtained, minimizing vertical distortion
What are drilling ships? Give an example
method of collecting sediments
Glomar Challenger (1968) which helped confirm theories of seafloor spreading & continental drift -> JOIDES Resolution -> Chikyu
What is a CTD package?
Used to determine conductivity, temperature, and depth of water
that big swinging thing off boats that people have gotten hurt by
What are 2 we can measure currents?
speed & direction can be computed if you have salinity and temperature
Chemical/radioactive tracers can be dissolved in water
