Oceanography Midterm #1

question

What is special about the Sargasso Sea?
answer

It is defined by the surrounding ocean currents
question

List Four Reasons to Care about the Ocean
answer

Lots of life (50% species), produces 70% of O2, 71% of Earth’s surface, major source (20% animal protein)
question

Compare Ocean depths to land heights
answer

ocean is 4.5 times greater than average land elevation
question

what percent of Earth is covered with water?
answer

97%
question

What percent of Earth’s water is found in the ocean
answer

71%
question

Compare and contrast the following (hypothesis, theory, law, fact)
answer

Hypothesis: Tentative explanations proposed Theory: Patterns emerge. If one or more of the relationships hold the hypothesis becomes a theory Law: Theories that evolve into larger constructs Facts: Law and theory can be statements of fact
question

The ocean compromises what percent of Earth’s mass?
answer

0.02%
question

Largest animal to ever inhibit Earth. What does it eat?
answer

Blue Whale. Eats up to 40 million krill a day
question

Why do waves break as they come ashore?
answer

Water is slowed by contact with the sea bed while the top of the wave is still moving fast so it rolls over and breaks
question

Why is there so much life around volcanic islands (seamounts)?
answer

There’s lots of nutrients because the deep ocean currents collide with the islands flanks
question

What do tuna eat and what eats them?
answer

Tuna eat plankton feeders and sharks eat tuna
question

Why do hammerhead sharks come to seamounts?
answer

The locals of the seamounts provide a cleaning service
question

what do sardines eat and what four organisms eat them?
answer

Sardines eat plankton and cape gullets, sharks (bronze whaler), dolphins, and whales eat them
question

Where do we find some of the roughest conditions? What does this do to the ocean productivity?
answer

Roughest conditions found near (south Atlantic) poles. it enriches the surface waters (food in abundance)
question

Basis of all life in the ocean?
answer

fighter plankton
question

largest migration of life on the planet. explain.
answer

Disappearance of the sun triggers 1,000 million tons of sea creatures searching for food near the surface (graze on fighter plankton)
question

Why do sea turtles lay their eggs on the same day?
answer

so predators on the beach are overwhelmed so many babies get to the water
question

why do herring go into shallow water?
answer

to breed
question

why do grey whales migrate such great distances?
answer

seeking the krill that came to feed off the herring eggs
question

how do killer whales kill a grey whale calf?
answer

they force themselves between mother and calf then leap onto it and push it under (drown it) and kill it
question

what is special about the North Star (Polaris) and why was it so important in early navigation?
answer

It doesn’t move so you can refer to it for navigation
question

Where did the Cook voyages go and what were their contributions?
answer

Went to South Pacific. They found data on ocean depths, wind directions, water temperatures, and surface currents
question

What was the echo sounder and why was this important to oceanography?
answer

It allowed measurements of seafloor bathymetry
question

Satellites are being used more and more to sturdy the oceans- why are they so valuable?
answer

They gather large scale data over short time periods
question

What prompted colonization of Polynesia and Viking exploration
answer

economic reasons
question

why did the Chinese set out in the 1400’s to launch “the greatest fleet the world had ever known”?
answer

To explore the other side of the world and convince nations China was the only civilized state
question

Why is meant by “reverse tribute”?
answer

Giving things to people to show their wealth
question

Who discovered North America?
answer

Vikings
question

What research question was the focus of the Glomar Challenge?
answer

To test a controversial hypothesis about the history of the ocean floor
question

When did oceanographic institutions get established and why?
answer

they evolved to ensure continuity of effort when demands became greater than any single voyages capability
question

Describe the initial surface of the Earth
answer

Sandy with lots of craters from collision
question

How and when did the moon form?
answer

3.9 billion years ago. Molten debris coalesced together after collision with something the size of Mars
question

“habital” zone
answer

right distance from the sun so the oceans don’t boil away/ freeze
question

where did the water come from the eventually filled the oceans?
answer

Commets showered earth with water
question

What is a thermophile?
answer

Organisms that can live in extreme environments
question

Whats the oxygen revolution? what caused it?
answer

Photosynthetic organisms producing enough oxygen to oxidize minerals dissolved in ocean and surface sediments
question

what’s the magnetic field do and how has it influenced how Earth developed?
answer

Magnetic field deflects solar wind and preserves our air
question

how do we think the planets formed and why do we have rocky and gases planets?
answer

Planets formed from space debris gravitating and being held together. We have rocky and gaseous planets because of their distance from the sun and solar winds
question

Three sources of hear that caused early earth to be molten?
answer

Frictional heating, impacts, radioactive decay
question

How does the composition of the crust differ from the whole-earth composition?
answer

The crust composition has light elements up and heavy elements down
question

Compare and contrast the lithosphere and asthenosphere
answer

Lithosphere: cool, outer layer, 70-200km, composed of continental/oceanic crusts and uppermost portion of mantle Asthenosphere: hot, partially melted, slowly flowing layer of upper mantle, 350-650km
question

Three types of plate boundaries and what occurs at each
answer

Divergent: spreading centers, new crust Convergent: sudbuction, crust destroyed Fault: sliding, lithosphere breaks
question

How old are the oldest ocean rocks- why so young?
answer

Less than 200 million years old because sediments are conducted at a plates leading edge
question

Greatest objections to Wegner’s hypothesis?
answer

That he only selected data supporting his hypothesis, ignoring contrary evidence
question

Why is the Earth’s interior still hot?
answer

Radioactive elements within Earth’s core and mantle continue to decay and produce heat
question

What is a volcanic island arc? Where do they form?
answer

Curving chains of volcanic islands/ seamounts that occurs parallel to concave edges of trenches
question

Would the most violent earthquakes be associated with spreading centers or subduction zones? why?
answer

Subduction zones because there was no evidence of new crust spreading centers must be balanced by destruction the crust plunges into the mantle(subduction zones are deeper and more violent)
question

What’s a hot spot and how can they be used to determine plate motion and rate?
answer

Plumes of magma rising from stationary sources of heat in the mantle
question

Why are tectonic terranes and how do they form?
answer

Isolated part of seafloor, island arc, plateau, continental crust, or sediment brought by seafloor spreading to a position adjacent to a larger continental mass
question

What does magnetic field do for us?
answer

It’s a force field that protects us from space weather and radiation
question

how can ancient pottery be used to help us understand the magnetic field?
answer

Pottery records the Earth’s magnetic field when it goes into the film. We know the rate of change in the magnetic field has been up and down but the last 300 years there has been a rapid fall
question

What would happen if the liquid core stopped moved?
answer

the dynamo would shut down
question

How fast is Earth’s core cooling?
answer

100 degrees per billion years
question

How often have magnetic field reversals take place?
answer

Once every 200,000 years
question

What has happened in the South Atlantic?
answer

Magnetic anomalies have begun under the ocean (reversing direction and cancelling out the Earth’s magnetic field)
question

Where do most earthquakes and volcanoes occur?
answer

Ring of fire and near the edges of tectonic plates
question

What’s the significance of magnetic strips- what do they tell us?
answer

They hold a record of reversals in Earth’s magnetic field
question

When did plate tectonics begin?
answer

3.2 billion years ago
question

What is the difference between an ocean and a sea?
answer

Seas are smaller than oceans and are located where land and ocean meet
question

What two instruments are needed to determine your longitude using the sun- why?
answer

sextant (determining latitude) and chronometer
question

What were the main stimuli to European voyages of exploration during the Age of Discovery?
answer

Trade, military one-upmanship
question

Why is the oldest ocean floor so young?
answer

Subduction. Oceanic crust gets colder and denser w/ age. It sinks into the upper mantle and is essentially a continuing cycle.
question

How could you convince a 10 yr old that the Earth is round?
answer

A. You could take them to the ocean and watch how ships don’t just appear on the horizon but rise above the curve on the planet B. The fact that shadows change over time would not happen on a flat planet
question

How is plate tectonics related to the rock cycle
answer

Earth materials get melted, buried, lifted, weathers and is pushed by the plate tectonic process. Rocks are this way because of this.
question

What is the curie point and why is it important regarding paleomagnetism?
answer

Temperature when materials lose their magnetic properties, replaced by induced magnetism
question

Why was determining longitude so important? Why is it more difficult than determining latitude? How was the problem solved?
answer

It’s the key to oceanic exploration and mapping. Inventing a sturdy clock that ran at a constant rate. A chronometer was the solution.
question

How is oceanography different from most of the other sciences?
answer

It involves many different kinds of sciences and not just one thing specifically. For example, oceanography involves geology.
question

Compare the five main oceans.
answer

Pacific= largest/ deepest Arctic= smallest, shallowest, ice-covered Atlantic= second largest, almost as deep Indian= mainly in southern hemisphere, almost as deep Antarctic Ocean= connects pacific, atlantic, indian oceans and is larger than the atlantic
question

What drives plate tectonics?
answer

Convection in the mantle
question

What did we learn about Mars (past and present)
answer

Today, Mars has no magnetic field but that it’s not always been the case. It had 20 to 30x the strength of Earth
question

When did Darwin’s voyage on the Beagle take place and what was it’s focus?
answer

Focus was to discover many organisms and it took place from 1831-36
question

List four ways that early explorers navigated the ocean
answer

1) following the coast line 2) map of places and general direction 3) using the sun and time of day 4) using the stars
question

Who invented the first navigation compass and why was it such a big deal?
answer

Chinese, it used the magnetic field to determine location and was a reverse tribute
question

What was so special about the Challenger expedition in 1872?
answer

one of the first purely scientific oceanographic expeditions

Get instant access to
all materials

Become a Member