ocean prelim 1 answers

1. How were heavy elements like carbon, nitrogen, copper and gold created?
   a. All elements, both light and heavy, were created during the moment of the Big Bang.
   b. All elements, both light and heavy, were created about 375,000 years after the Big Bang when the universe cooled enough to form stable atoms.
   c. All heavy elements were created inside of stars or when stars exploded.
   d. About 20% of the heavy elements today were created initially from the Big Bang and then later another 80% were created inside of stars or when stars exploded.

c. All heavy elements were created inside of stars or when stars exploded.

2. How do stars form?
   a. All the stars we see today formed during the initial Big Bang and have been hurtling outward through space and clustering into large galaxies ever since.
   b. Stars started forming after the intense heat of the Big Bang cooled and cold hydrogen gas began condensing into large-mass objects due to gravitational attraction. When an object’s mass becomes very large, the gravitational compression within the center of the object makes its interior hot enough to ignite thermonuclear fusion reactions.
   c. Intensely hot plasma (heated from the initial Big Bang) collapsed under gravity to form very large cohesive masses of this hot matter, which we now call stars.
   d. Stars formed when the Cosmic Microwave Radiation left over from the Big Bang heated dense clouds of hydrogen to extreme temperatures and then these dense clouds began to glow white hot.

b. Stars started forming after the intense heat of the Big Bang cooled and cold hydrogen gas began condensing into large-mass objects due to gravitational attraction (eventually igniting fusion).

3. How was our moon formed?
   a. A moon that had initially formed around Mars was pulled away from Mars by the stronger gravity of the much larger Earth and was subsequently drawn into Earth’s orbit.
   b. Small planetesimals were captured by Earth’s gravity and then these planetesimals slowly collided over a 500-million-year period to form our moon.
   c. An ancient planet the size of Mars hit the Earth, and the ejected material that subsequently coalesced to form the moon.
   d. An ancient tectonic plate collision in early earth history was so violent that it ejected a large piece of tectonic plate into orbit.

c. An ancient planet the size of Mars hit the Earth, and the ejected material that subsequently coalesced to form the moon.

4. Our understanding of where the water that fills the Earth’s oceans came is still of some scientific debate, but most scientists currently think it was likely brought to earth by comets.
   a. True
   b. False

b. False

5. If you scaled the Earth down to the size of a beach ball (half meter diameter), how thick would the ocean be?
   a. About 1 micrometer
   b. About 0.1 millimeter
   c. About 100 millimeters
   d. About 10 centimeters

b. About 0.1 millimeter

6. How quickly did life appear on Earth after the Earth cooled and the oceans filled?
   a. Remarkably quickly (less than 500 million years).
   b. It took a pretty long time for life to get started (more than a billion years).
   c. It took a very long time for life to finally catch hold on Earth (about 2.5 billion years).

a. Remarkably quickly (less than 500 million years).

7. When did life on land first appear?
   a. 4 billion years ago
   b. 2.5 billion years ago
   c. 550 million years ago
   d. 66 million years ago

c. 550 million years ago

8. Which animal group represents the first appearance of a backbone that evolutionarily led to you?
   a. The first vertebrates were mammals.
   b. The first vertebrates were fish.
   c. The first vertebrates were amphibians that lived both on land and in the water.
   d. The first vertebrates were reptiles.
   e. The first vertebrates were dinosaurs.

b. The first vertebrates were fish.

9. What is the nature of the earliest known fossil?
   a. A Body fossil
   b. A Trace fossil
   c. A Chemical fossil

c. A Chemical fossil

10. When did life on Earth transition from being just simple prokaryotic organisms floating around in the ocean to more complex eukaryotic organisms and multicellular organisms?
    a. About 550 million years ago
    b. About 1 billion years ago
    c. About 2 billion years ago
    d. About 4.5 billion years ago

c. About 2 billion years ago

11. Which came first, evolution of bacterial photosynthesis and the associated production of oxygen or the evolution of multicellular organisms?
    a. evolution of bacterial photosynthesis and oxygen came first.
    b. evolution of multicellular organisms came first.

a. evolution of bacterial photosynthesis and oxygen came first.

12. What was the Cambrian Explosion?
    a. A period of Earth history that underwent a dramatic increase in explosive volcanism leading to the first mass extinction event on Earth.
    b. An event in Earth history where most of the major animal phyla were created in a relatively short period of time.
    c. It was a moment of explosive scientific discovery about the evolution of life on Earth that had its beginning in a now-famous scientific meeting held at Cambridge University on August 22, 1897.

b. An event in Earth history where most of the major animal phyla were created in a relatively short period of time.

13. What is the geologic age (period) of the rocks around Ithaca?
    a. Devonian
    b. Carboniferous
    c. Ordovician

a. Devonian

14. Which type of crust is denser?
    a. Oceanic Crust.
    b. Continental Crust.

a. Oceanic Crust.

15. What evidence did Alfred Wegner use to confirm that the continents had drifted over geologic time?
    a. The remarkable fit of the South America and West Africa coastlines.
    b. Fossil and mineral belts on separate modern-day continents aligned neatly when the continents were artificially moved into a single super-continent.
    c. Magnetic anomalies found in solidified continental rock aligned perfectly when the continents were artificially moved into a single super-continent.
    d. Once plate tectonics were discovered, he quicky noted that this process would be capable of moving continents around.

b. Fossil and mineral belts on separate modern-day continents aligned neatly when the continents were artificially moved into a single super-continent.

16. Why was extensional faulting along the axis of mid-ocean ridges an important piece of evidence leading eventually to the development of plate tectonic theory?
    a. Because extensional faulting only occurs where magma erupts to the surface.
    b. Because extensional faulting is an indicator of extensive earthquake activity.
    c. Because extensional faulting only occurs in recently formed rock.
    d. Because extensional faulting occurs when solid rock is pulled apart.

d. Because extensional faulting occurs when solid rock is pulled apart.

17. What kind of tectonic process takes place in deep sea trenches?
    a. This is a region where new oceanic crust is formed.
    b. This is where old oceanic crust is sinking back into the mantle.
    c. This is where new ocean basins are in the earliest stages of being born.
    d. This is where two tectonic plates slide laterally past each other (i.e., a Transform Fault region).

b. This is where old oceanic crust is sinking back into the mantle.

18. How are continents moved around on Earth over geologic time?
    a. Magnetic minerals in continents realign and move continents when Earth’s magnetic field moves.
    b. Continents are moved when the tectonic plates that they are a part of move.
    c. The moon’s gravity drags continents through oceanic crust.
    d. New continental crust is made while old sinks, giving the illusion of motion.

b. Continents are moved when the tectonic plates that they are a part of move.

19. Which geologic feature is a result of oceanic crust colliding with continental crust?
    a. Hawaiian Islands
    b. Philippine Islands
    c. Andes Mountains
    d. Himalayan Mountains

c. Andes Mountains

20. Why is the age of continental crust so much older than the age of oceanic crust?
    a. Continents formed early when Earth was hot

    oceanic crust formed much later.
    b. Oceanic crust could not form until enough water filled the oceans.
    c. Ocean crust is constantly being made at mid-ocean ridges and then recycled back into the mantle in subduction zones.

c. Ocean crust is constantly being made at mid-ocean ridges and then recycled back into the mantle in subduction zones.

oceanic crust formed much later.
b. Oceanic crust could not form until enough water filled the oceans.
c. Ocean crust is constantly being made at mid-ocean ridges and then recycled back into the mantle in subduction zones.

c. Ocean crust is constantly being made at mid-ocean ridges and then recycled back into the mantle in subduction zones.

21. How were the Hawaiian Islands created?
    a. Tectonic collision between two oceanic plates.
    b. Plate divergence along the Pacific mid-ocean ridge.
    c. Mantle hot spot that upwelled magma to the surface to form underwater mountains that eventually grew to become islands.
    d. Formed near Alaska and were transported to current location.

c. Mantle hot spot that upwelled magma to the surface to form underwater mountains that eventually grew to become islands.

22. Where are siliceous and calcareous oozes typically found?
    a. In coastal regions near river outflows.
    b. Away from coasts in regions of high biological productivity.
    c. Away from coasts in regions of low biological productivity.
    d. All of the above.

b. Away from coasts in regions of high biological productivity.

23. Analysis of fossil shells in sediment cores extracted from the sea floor can yield information about:
    a. Species extinction through time.
    b. Past levels of biological productivity.
    c. Past temperatures of the ocean’s surface.
    d. All of the above

d. All of the above

24. Which wave process gives rise to the nice, clean sets of waves that have similar wavelength that come ashore in Hawaii from Alaskan storm?
    a. Wave refraction
    b. Wave dispersion
    c. Constructive wave addition
    d. Mixed wave addition
    e. Longshore transport

b. Wave dispersion

25. What typically happens to wave energy as it approaches a coastal headland?
    a. The wave energy is focused to produce larger waves.
    b. The wave energy is de-focused to produce smaller waves.
    c. The distribution of wave energy is unchanged as the waves move toward the shoreline.

a. The wave energy is focused to produce larger waves.

26. If you are caught in a rip current, what should you do?
    a. Swim straight back to shore, the same way you came offshore.
    b. Swim along the shore for 10 to 20 meters, then back to shore, and then call Bruce.
    c. Swim along the shore for about 2 kilometers (the typical width of a rip current) and then back to shore.

b. Swim along the shore for 10 to 20 meters, then back to shore, and then call Bruce.

27. What is a storm’s fetch?
    a. It is the rotation rate of the storm system.
    b. It is the translation speed of the storm system.
    c. It is the distance over which the storm is able to recover energy lost to viscosity forces.
    d. It is the diameter of the storm system.

d. It is the diameter of the storm system.

28. How fast does the tsunami wave propagate?
    a. About 5 miles per hour
    b. About 50 miles per hour
    c. About 500 miles per hour
    d. About 1,500 miles per hour

c. About 500 miles per hour

29. What should you do if you were somewhere near a beach and suddenly felt a small earthquake?
    a. You should move immediately to higher ground or a tall building.
    b. Since the earthquake felt small, you can safely ignore things and stay close to the beach.

a. You should move immediately to higher ground or a tall building.

30. In the video of the Japanese tsunami propagation across the Pacific that was shown in class, which of the following best expresses how the wave propagated?
    a. It propagated as a clean wave front spreading out from a single source with slight bending of the wave front due to bottom depth changes.
    b. There were two distinct wave fronts that initially formed about 100 km apart near the coast of Japan.
    c. Many individual tsunami waves formed a highly complex interference pattern.

a. It propagated as a clean wave front spreading out from a single source with slight bending of the wave front due to bottom depth changes.

31. Which force is involved in the creation of the tidal bulge located on the far side of Earth that is opposite from the side facing the moon?
    a. Gyro-dynamic force
    b. Geodesic force
    c. Coriolis force
    d. Centrifugal force
    e. Trapezoidal force

d. Centrifugal force

32. What orbit path does the moon take around the Earth?
    a. The moon’s orbit around the Earth is along the Earth’s equator.
    b. The moon’s orbit around the Earth is at a 28° inclination relative to the equator.
    c. The moon’s orbit around the Earth changes with time between 28° inclined and along the equator.
    d. The moon has a polar orbit.

b. The moon’s orbit around the Earth is at a 28° inclination relative to the equator.

33. When do Spring Tides occur?
    a. During a Full Moon
    b. During a Half Moon
    c. Only during April through May
    d. Both a and c

a. During a Full Moon

34. Why do we get rotary tides?
    a. Coriolis force alone.
    b. Blocking by continents alone.
    c. The combination of Coriolis force and blocking by continents.
    d. Winds spin the tide crest directly.
    e. Continents + winds.

c. The combination of Coriolis force and blocking by continents.

35. Why do you not get a significant tidal range in Hawaii?
    a. Hawaii is too small for tide to pile up.
    b. Hawaii is near a co-tidal line
    c. Hawaii is near an amphidromic point
    d. Gravity of the moon is reduced there.

c. Hawaii is near an amphidromic point

36. If you have high pressure at 30ºN and low pressure along the equator, why do the surface winds not move in a straight line southward from high to low pressure? Why do they instead turn to the west?
    a. East-west pressure gradient from heating differences.
    b. Coriolis force.
    c. Mountains + heating differences.

b. They are turned by the Coriolis force.

37. Does the mixing depth of the surface ocean get shallower or deeper as you transition from winter into spring and summer in temperate (mid-latitude) regions?
    a. Mixed layer gets deeper as surface warms.
    b. Mixed layer gets shallower as surface warms because warmer water is more buoyant and harder to mix downward.

b. The mixed layer gets shallower as the surface layer warms because the warmer water is more buoyant and harder to mix downward.

38. What is Ekman Transport?
    a. Western boundary current transport (e.g., Gulf Stream).
    b. Wind-driven transport of a relatively thin (~50 m) slab of surface water.
    c. Downward transport of cold salty dense surface water in polar regions.
    d. Global conveyor belt transport.

b. The movement/transport of a relatively thin (c.a., 50 meters) slab of surface water that occurs in direct response to wind forcing.

39. How is the mound of surface water in the middle of the subtropical gyre formed?
    a. Moon’s gravity pulls it up.
    b. Freshwater flooding from continents.
    c. Trade Winds + Westerlies drive Ekman convergence into the gyre center.
    d. Ekman Spiral draws deep water up in the center.

c. The action of the Trade Winds and the Westerly Winds collectively drive an Ekman Layer convergence into the middle of the subtropical gyre.

40. What drives subtropical gyre rotation?
    a. Winds apply torque directly like unscrewing a jar lid.
    b. Upward flow from Ekman divergence spins it up.
    c. A center of high pressure under a mound of water drives currents outward and Coriolis deflects them.

c. A center of high pressure under a mound of water drives ocean currents radially outward and these currents are deflected by the Coriolis Force.

41. If winds are blowing from north to south along the west coast of the United States, would the Ekman Layer move onshore or offshore?
    a. Onshore
    b. Offshore

b. Offshore

42. How is the age of bottom water in the deep ocean measured?
    a. Chemical isotope ratios (e.g., 16O:18O)
    b. Temperature and salinity
    c. Marine plankton identification
    d. 14C concentration

d. Based on 14C concentration.

43. How long does it take for deep ocean water to move from the North Atlantic to the North Pacific?
    a. About 100 years
    b. About 200 years
    c. About 2,000 years
    d. About 10,000 years

c. About 2,000 years

44. The reason oceanographers care so much about the movement of the conveyor belt circulation is because:
    a. It moves a lot of heat from the equator to higher latitudes.
    b. It moves a lot of fresh water from coastal regions to the open ocean.
    c. It strongly impacts the propagation of Rotary Tides.

a. It moves a lot of heat from the equator to higher latitudes.

45. Which statement best describes the current state of scientific knowledge regarding the possibility that the Atlantic Meridional Overturning Circulation (AMOC) might collapse this century?
    a. Scientists are highly confident AMOC will collapse this century.
    b. Scientists are highly confident AMOC will not collapse this century.
    c. Scientists have modest but steadily growing concern that AMOC could collapse this century.

c. Scientists have modest but steadily growing concern that AMOC could collapse this century.

46. What happens to the Walker Circulation Cell during the transition from normal conditions to El Niño conditions?
    a. The Walker Cell speeds up.
    b. The Walker Cell slows down or reverses.
    c. The Walker Cell moves northward ~10° latitude.
    d. The Walker Cell moves southward ~10° latitude.

b. The Walker Cell slows down or reverses.

47. What happens to the Warm Pool during the transition from normal conditions to El Niño conditions?
    a. Warm Pool moves from Eastern Pacific (Peru) to Western Pacific (Australia).
    b. Warm Pool moves from Western Pacific (Australia) to Eastern Pacific (Peru).
    c. Warm Pool position not affected.

b. The Warm Pool propagates from the Western Pacific (near Australia) to the Eastern Pacific (near Peru).

48. During an El Niño event, biological productivity off the California coast can be expected to increase?
    a. True, El Niño increases primary production.
    b. False, El Niño decreases primary production and lowers growth for the food web.

b. False, El Niño events typically lead to a decrease in primary production that lowers growth for the rest of the food web.

49. How can the effects of El Niño conditions in the Pacific be transmitted to the far reaches of the globe?
    a. Variation in the position of the Kuroshio Current
    b. Variation in the position of the Jet Stream in the atmosphere
    c. Small variation in Earth’s rotation

b. Variation in the position of the Jet Stream in the atmosphere

50. What happens to the global-average temperature during an El Niño year?
    a. Global temperatures increase during an El Niño year.
    b. Global temperatures decrease during an El Niño year

a. Global temperatures increase during an El Niño year.