Intro Msci Final Study Guide

How/Why did early civilization use the oceans?

Food, Trade, Transportation

Why were the oceans explored in the Middle Ages/Age of Exploration?

Glory/God (colonization), Gold (trade)

What was the focus of oceanography in the 19th/20th centuries?

Charting/Mapping, Bathymetry, Wind Patterns

First Major Oceanographic Cruise

Challenger Expedition

What political event sparked a surge in marine science?

World War II

What’s the focus of modern oceanography?

Scientific Discovery

Approximate age of the Earth

4\.5 billion years, based on radiometric dating

Water is hypothesized to have come from…

precipitates of volcanic activity, asteroids, and/or water already present on Earth’s core

Earth’s water reservoirs, largest-smallest

oceans, ice caps/glaciers, groundwater, rivers/lakes, atmosphere

What is the residence time of a body of water with a volume of 1,000,000 km^3 and an inflow of 25,000 km^3/year

40 years

Approximate residence time of earth’s oceans

3,000 years

Which hemisphere contains most of the world’s oceans

Southern

Average depth of the oceans

3,800 mWhat

What percent of ocean area is shallower than 5,000 m?

65%

_____ increases as you move toward the center of the Earth

pressure, density, temperature

What is the sequence of Earth’s layers based on physical characteristics?

lithosphere, asthenosphere, mesosphere, outer core, inner core

The ___ *layer of Earth is relatively ductile, meaning the layers above it can “float” on top of it via* __ equilibrium

Asthenosphere, Isostacy

How does oceanic crust differ from continental crust?

Oceanic crust is younger, thinner, and more dense

What evidence was there for continental drift?

“Puzzle-Piece” fit of continents, their rocks/mountain ranges/glacial deposits, and their fossil records

What process drives sea-floor spreading, and how?

Convection currents in Earth’s mantle, bringing up new crust at mid-ocean ridges, and subducting/melting older crust in deep sea trenches

What evidence was there for sea-floor spreading?

Earthquake/heat distributions, carbon dating/thickness/ magnetic “fossil” bands of rocks,

Which model best describes the mechanisms behind plate tectonics?

Ridge-Push, Slab-Pull

What is the typical rate for sea-floor spreading?

cm/year

Which of these denotes a spreading center/divergent plate boundary?

C-the ocean ridge (and rift valleys)

Which of these denotes a convergent plate boundary?

B and D-the trenches

Which features characterize ocean-continent and continent-continent convergent boundaries?

Mountain ranges (ex. Volcanic Andes Mountains along Peru Trench, Himalayas along Asia/India boundary)

What features characterize an ocean-ocean convergent boundary?

Volcanic Island Arc (ex. Aleutian Islands)

What kind of plate boundary is marked?

Transform Boundary-San Andreas Fault (North American and Pacific Plates sliding past one another)

What forms over hot spots?

Volcanic Island/ Seamount Chains (ex. Hawaiian Islands over Pacific Hotspot)

What kind of continental margin is pictured?

Passive

What kind of continental margin is pictured?

Active

Where would you expect to find a wider continental shelf?

Along a passive margin

Where would you expect the strongest earthquakes and volcanism?

D-the active margin/subduction zone

What is this feature?

Submarine canyons formed by turbidity currents along continental shelf

What is this seafloor province?

Continental rise

What is this seafloor province?

Abyssal Plain

What is this feature?

Atoll over a sinking seamount/guyot

What is this seafloor province?

Seamount

Where would you find the oldest and thickest sediments, and why?

D-continental margins, older crust far from the mid ocean ridge - the heavier, more abundant neritic (land) deposits immediately sink there and accumulate without being dissolved

As sediment grain size decreases…

…sinking rate decreases

Which sediment type is formed from chemical precipitation of sediments in sea water?

Hydrogenous (ex. manganese nodules, hydrothermal vents)

The depth at which calcareous ooze begins to dissolve is called…

…the lysocline

The depth at which ALL calcareous ooze is dissolved is called…

…the carbonate compensation depth. Deposition =/< absorption

Which sediments accumulate in the deepest regions of the abyssal plains?

Silicious

The uneven charges in this molecule indicate…

…polar hydrogen bonds

The specific heat of water is…

…comparatively high, allowing it to prevent extreme changes in global temperatures

The latest heat of water is…

…comparatively high-it takes large amounts of energy to change the chemical state of water, so it will absorb more heat and transport it around the globe to moderate climate

Why does ice float?

Hydrogen bonds expand past 4 degrees c and make the solid phase less dense than the liquid phase

As pressure, salinity, and depth increase, density of water…

…increases

What makes water such a good solvent?

Polar hydrogen bonds, which attract the polar bonds of NaCl and break it apart

Major constituents of seawater

Na^+, Cl^-, Ca^2+, K^+, SO4^2-

Average ocean salinity

35 \[ppt/psu\]

Salinity range of brackish water

0\.5-30 \[ppt/psu\]

variations in salinity are mainly caused by…

…regional variations in evaporation/precipitation

Salts in the ocean primarily cone from…

…volcanic gases/precipitates from earth’s mantle, and dissolution/decayof river sediment deposits and organic matter-constant input and output through these sources

Which of these best describes a hydrothermal vent?

Cool seawater enters fractures in the ocean’s crust near mid ocean ridges, is superheated, and propelled back into the ocean. Some elements from the Earth’s mantle are absorbed by seawater, while others precipitated out, through this process.

Atmospheric and ocean currents transport heat around the globe by…

…convection cells, characterized by elevated precipitation and warm (air/water) rising in one location, and dry climates and cold (air/water) sinking in another

Coriolis Effect

Moving fluids deflect to the right in the northern hemisphere and to the left in the southern hemisphere, due to earth’s rotation

Where does warm, moist air rise as part of the atmospheric convection cells?

Equator and 60 degrees latitude

Where does cool, dry air sink as part of atmospheric convection cells?

Poles and 30 degrees latitude

Where would you find the trade winds?

Between o and 30 degrees latitude

Where would you find the westerlies?

Between 30 and 60 degrees latitude

Where would you find the polar easterlies?

Between 60 and 90 degrees latitude

What direction are the winds moving during monsoon season?

From ocean to land

Cool sea breezes at the coast are due to…

…land heating faster than the ocean during the day

Hurricanes…

…are low-pressure systems that form over tropical waters and transport heat from equator-poles along the major atmospheric wind bands

What is this layer of the surface ocean called?

Mixed Layer

The layer of rapidly changing temperature (in yellow) is called…

…the thermocline

The difference between these two profiles is that…

…B is more strongly stratified than A and is typical of summer

What direction do surface ocean currents travel in the northern hemisphere?

45 degrees to the right of the wind

In the northern hemisphere, what is the direction of net Beckman transport?

90 degrees to the right of the wind

If you’re in the southern hemisphere and the dashed red line is the direction of the wind, which lines indicate the direction of surface currents and Beckman transport?

B is the direction of surface currents, A is the direction of net Eckman transport

What two forces are balancing these large currents, what direction do they rotate, and what can the center be described as?

Geostrophic gyres-balanced by Coriolis effect and gravity, traveling clockwise in the northern hemisphere and counterclockwise in the southern hemisphere with a convergence zone “hill” in the center

The Gulf Stream is an example of…

…western intensification

Western boundary currents are ___ __, , and__ _____ than eastern boundary currents

faster, narrower, and deeper

What are these breaks in the current?

A is a cold-core eddy and B is a warm-core eddy

Surface ocean convergence zones are characterized by…

a deepened thermocline and downwelling

Surface ocean divergence zones are characterized by…

an elevated thermocline and downwelling

This northern hemisphere location along an Eastern Boundary Current is likely characterized by…

…coastal upwelling

An El Niño is…

…A regularly occurring reversal of the Indonesian Low and South Pacific High, and the flow of warm water across the Pacific from west to east, which deepens the thermocline and enhances upwelling

a large body of water that has similar values of temperature and salinity throughout, and the boundary between them, are called…

…a water mass, separated by a front

What is the density of water with T=10 and S=35.1?

1\.0270

What are the typical values of Mediterranean water?

T=10, S=35.6, P is between 1000-1500

Which of these water masses will reside at the bottom of the water column?

D

Which profile depicts an unstable water column?

C-it will initiate a convection current

What is happening to the water column at this location?

Sinking of bottom water, as surface water gets cold and saltier as it moves towards the poles, and water from lower latitudes comes to replace it via convection currents

All of these are locations of deep water formation except…

…C-no bottom water formation in the pacific

Due to climate change, thermohaline circulation around the globe is….

…weakening

The region of the water column with enough light for photosynthesis is called the…

…photic zone

“benthic” refers to…

…the seafloor

As death increases, light…

…decreases

Which wavelength of light penetrates deepest in ocean water?

Blue

which group of marine organisms are unable to move against the currents?

Plankton

Which group of plankton are autotrophic?

Phytoplankton-conduct photosynthesis

As the size of marine organisms increases, their abundance typically *___ and their surface area:volume ratio* __

decreases,increases

Which group of marine organisms are able to swim against the currents?

Nekton

Which group(s) of plankton are heterotrophic?

Bacterioplankton, zooplankton

Which group are primary consumers in the oceanic food chain?

Zooplankton

Which group are primary decomposers in the oceanic food chain?

Bacterioplankton

Net primary Production

overall gain/loss of biomass in producers (photosynthesis-respiration)