OCE1001, INTRODUCTION TO OCEANOGRAPHY, Fall, 2016 THIRD MID-TERM EXAMINATION Test No. 0001 Name: ______READ THIS!!!! Put your name in the blank above. Read all questions carefully, and answer only the question which is asked. You may find the following equations useful: C = (gL/2) = 1.25 L (m/s) Where: C = speed of a wave and: g = gravity = 9.8 m/s2 C = (gD) = 3.1 D (m/s) L = wavelength of a wave C = 1.56 T (m/s) D = water depth C = L/T T = period of a wave
PLEASE WRITE NEATLY. Matching: (8 pts) Do not put these on the scantron sheet. 1. ____ amphidromic A. disturbance of wave is parallel to wave movement. 2. ____ bore B. opening under an eroded headland. 3. ____ eustatic C. part of the beach that is accessible to the public. 4. ____ longitudinal D. point where the tide neither rises nor falls. 5. ____ sea cave E. submerged area of coast eroded flat by waves. 6. ____ recreational beach F. tide rises suddenly as one or a few waves come up a river. 7. ____ transverse G. wave having motion at right angles to the direction of wave movement. 8. ____ wavecut terrace H. worldwide change in sea level.
Multiple Choice: (2 pts each) Put the answers to these questions on the scantron sheet. 1. A wave in which the height is 2 meters, the wavelength is 600 m, and the water depth is 150 m would be considered to be a: a. deep water wave. b. plunging breaker. c. spilling breaker. d. tsunami. e. shallow water wave.
2. Which of these factors is not necessary to form large wind waves? a. all of these are necessary. b. high wind speed. c. great water depths. d. long wind duration. e. long fetch.
3. Your best strategy if you are caught in a RIP CURRENT is to: a. accept inevitable death. b. swim back to shore directly against the current. c. swim with the current until it reverses and takes you back to shore. d. swim parallel with the shore until out of the current, then swim back to shore. e. float with the rip current until it stops, and catch another rip current back to shore.
4. The process that bends waves as they approach shallow water is: a. refraction. b. diffraction. c. reflection. d. infraction. e. deletion.
5. If waves are approaching a groin from the southwest (Figure 1), then the beach on the west side of the groin will become ___ while the beach on the east side of the groin will become ___. a. wider, wider b. the waves will have no effect on the width of the beach. c. narrower, narrower d. wider, narrower e. narrower, wider
6. In Figure 2, the features labeled C, O, A, S, and T are, respectively: a. baymouth bar, hook, tombolo, spit, barrier island. b. hook, tombolo, spit, barrier island, baymouth bar. c. tombolo, spit, barrier island, baymouth bar, hook. d. spit, barrier island, baymouth bar, hook, tombolo. e. barrier island, baymouth bar, hook, tombolo, spit.
1 7. The factor that is most important in controlling the speed of a wave in "shallow" water is the: a. height of the wave. b. salinity of the water. c. depth of the water. d. steepness of the wave. e. wavelength of the wave.
8. The most important cause worldwide of waves, in terms of total energy, is: a. meteorites. b. winds. c. earthquakes. d. tides. e. none of these.
9. If we follow the motion of water in a deep water wave, it will move: a. with the wave, as a mound of water moving over the ocean. b. vertically only, up and down as the wave passes by. c. in an elliptical path in deep water only. d. in circles, with the size of the circles increasing as depth increases. e. in circles, with the size of the circles decreasing as depth increases.
10. The PERIOD of a wave is: a. the number of waves that pass a given point in a given time. b. the distance from the top of a wave to the still water level. c. the name for the motion of a particle of water in a water wave. d. the depth to which waves can "feel" the ocean bottom. e. the time it takes for an identical point on two successive waves to pass a given point.
11. In a "fully developed sea", the waves will be moving: a. as capillary waves. b. as surging surf. c. slower than the wind. d. faster than the wind. e. at the same speed as the wind.
12. A DEEP WATER wave BREAKS when: a. the water depth decreases to 1/2 of the wavelength. b. the windspeed exceeds the wavespeed. c. the height exceeds 1/7th of the wavelength. d. the height exceeds 0.8 of the depth. e. the height exceeds 10 m.
13. SPILLING WAVES occur near the beach instead of PLUNGING OR SURGING WAVES when: a. the beach is steep. b. the beach is not very steep. c. the beach is composed of fine sand. d. the waves are smaller. e. the wind is blowing out to sea.
14. The reason that extremely large waves (50 ft + high) occur on the coast of Hawaii at the location known as "Jaws" is that: a. they form due to extreme tidal effects. b. refraction of waves over a submerged reef increases their size. c. they are funneled up a river mouth. d. the water is very deep in that location. e. the beach is extremely steep at that location.
15. The separation of ocean waves emanating from a storm center into groups of approximately constant wavelength and period is called: a. dispersion. b. refraction. c. reflection. d. separation. e. distinction.
16. Which of the orbital configurations shown in Figure 3 would result in a NEAP tide? The letters m,n,o,p,q,r,s,t are possible positions of the Moon orbiting Earth. a. o and s. b. n only. c. p and t. d. m and q. e. n and r.
17. If you are at the beach, which of the following observations is likely to result in a high tide at your location, at the time you make your observation? a. The moon is directly overhead. b. The moon is rising from the eastern horizon. c. The moon is setting into the western horizon d. The moon is full. e. The moon is half-full.
18. The celestial body with the strongest influence on ocean tides is: a. the Sun. b. Jupiter. c. Mars. d. the Moon. e. In fact, the Sun and Moon have about equal influences 2 19. We would expect that, through geologic time, tidal friction on the Earth results in all of the below except: a. slowing down of the Earth's rotation. b. an increase in the length of the Earth's day through time. c. a decrease in the number of days in the Earth's year through time. d. fewer daily growth bands on fossil shells today than in the past. e. a longer time for the Earth to orbit the sun today than in the Earth's past history.
20. The length of a Tidal Day is about: a. 12 hours. b. 12 hours and 25 minutes. c. 24 hours. d. 24 hours and 50 minutes. e. 28 days.
21. The primary source of sand at most coastlines is: a. biogenic activity. b. glacial transport. c. rivers. d. windborne dust. e. waves pushing up sand from very deep water.
22. Which of these factors has the potential to affect global sea level rapidly (thousands of years) by up to 100-200 meters? a. tectonic uplift or subsidence of coastlines. b. changes in global erosion rates. c. changes in glaciation. d. changes in oceanic temperatures. e. changes in the rate of seafloor spreading.
23. In Figure 4, the features labeled 1, 2, 3, and 4 are, respectively: a. sea arch, headland, sea stack, sea cave. b. sea stack, headland, sea cave, sea arch. c. berm, beach scarp, foreshore, sand bar. d. sea stack, sea arch, sea cave, headland. e. baymouth bar, spit, barrier island, tombolo.
24. Which of these features would indicate the presence of an emergent coastline? a. a fjord. b. a baymouth bar. c. extensive sedimentation. d. an elevated beach terrace. e. an estuary.
25. Which of the following factors contributing to the development of a coastline is most important? a. All of these are equally important. b. Original Geology of the coastline. c. Tides and Currents. d. changes in Sea Level. e. the amount of Wave Action.
26. "New Jersey-ization" refers to: a. filling bays with landfill to produce new real estate. b. hard stabilization all along the coast, with the resultant destruction of the beach. c. the gradual pollution of all marine environments. d. building condominiums into the sea. e. the continual replenishment of beaches with offshore mud.
27. Why are salt marsh mud and oyster shells found on seaward sides of Barrier Islands today? a. They were originally deposited on the sides closest to the mainland and the Barrier Islands migrated landwards over them. b. They were originally deposited there. c. They were transported there by longshore drift. d. They were dumped there during dredging of salt marshes. e. They were blown there by strong winds at the end of the last glaciation.
28. A predictable outcome of building a seawall to protect a shore building is: a. decreased rates of local sea level rise. b. long term, cost free protection of the building. c. building sand up against the seawall. d. formation of a wide, flat beach. e. the loss of the recreational beach.
29. What did the early settlers on NC barrier islands do to prevent their houses from being destroyed by floodwaters? a. all of these. b. cut trapdoors in the floor to allow water to enter. c. place the house on pilings above the expected level of flooding. d. placed heavy weights inside the house to keep from being swept away. e. fastened the houses to the ground with cables and anchors.
3 30. Barrier Islands are ___ places to build homes because: a. good, they are geologically stable features. b. good, they are well protected from waves. c. poor, they tend to migrate or wash away. d. poor, the highest point is below high tide. e. poor, they are seismically active.
Non-Multiple Choice. You MUST do #1. You must do a total of seven and only seven of questions 1-12 (6 pts each). 1. For an ocean wave with the following characteristics, calculate the speed of the wave. You may find the equations on the first page of the exam useful. Wavelength = 1000 meters, Water Depth = 1600 meters, Wave Height = 16 meters. SHOW ALL OF YOUR WORK, INCLUDING HOW YOU DECIDED ON WHICH EQUATION TO USE. ------(Note: several lines available for this on the actual test) ------
2. Match these wave terms to their definitions: ____ crest A. lowest part of a wave. ____ fetch B. highest part of a wave. ____ height C. distance over which the wind blows. ____ period D. distance from top to bottom of a wave. ____ trough E. bending of a wave due to changing speeds. ____ refraction F. depth below which no motion from a wave is felt. ____ wave base G. distance between any two identical parts of successive waves. ____ wavelength H. time necessary for one wavelength of a wave to pass by.
3. Describe the development of storm waves, starting with a flat calm, increasing to strong, hurricane or near- hurricane force winds. How do the waves change, starting with the smallest and building to the largest waves? At what point do the waves in the open ocean begin to break, and why? Then, what happens to the waves as they leave the immediate area of the storm? ------(Note: several lines available for this on the actual test) ------
4. What are the ways that sealevel at coastlines changes? Discuss these ways, including information about whether the changes are worldwide or local, how fast the changes can occur, and how much sealevel can change as a result. ------(Note: several lines available for this on the actual test) ------
5. Match the observation with the type of tide you would expect. (Hint: draw the configuration of Earth, ocean, and astronomical bodies to see what this would do to the tide.) _____ moon is full. A. High tide. _____ moon is half-full. B. Low tide. _____ moon is new. C. Neap tide _____ moon is on the horizon. D. Spring tide. _____ moon is overhead. E. Cannot determine the tide from this information. _____ sun is on the horizon. (Note: some of these answers will be used more than once; _____ sun is overhead. all answers will be used at least once.)
6. Several structures were discussed in the video, "The Beaches Are Moving" that were designed to make alterations in a coastline: Groins, Jetties, and Seawalls. Discuss what each one is designed to do, how it does it, and any problems this might cause. ------(Note: several lines available for this on the actual test) ------
4 7. What happens as a wave in very deep water approaches shallow water? At what point does it become a "shallow water wave", and what are the changes to the overall shape of the wave, to the measurable properties of the wave (such as wave speed, height, energy, wavelength, period, and direction), and to the motion of the water particles in the wave a. The wave becomes a shallow water wave when: ______b. The motion of the water particles in the wave changes from ______to ______c. The wave speed: decreases stays the same increases (circle correct answer) d. The wave height: decreases stays the same increases (circle correct answer) e. The wave energy: decreases stays the same increases (circle correct answer) f. The wave wavelength: decreases stays the same increases (circle correct answer) g. The wave period: decreases stays the same increases (circle correct answer) h. The wave direction: bends towards the shore stays the same bends away from shore. (circle correct ans.)
8. Discuss the forces on a surfboard that enable the surfer to stay on the face of a wave. What has to happen to these forces for him/her to stay there, and how does the surfer move up or down the wave face? ------(Note: several lines available for this on the actual test) ------
9. Coastlines can be characterized as: emergent, submergent, depositional, and erosional. Discuss what each of these terms means in the context of coastlines, and give examples of coastlines or coastline features that would be classified as each of these, and explain how they formed. ------(Note: several lines available for this on the actual test) ------
10. To the right is a map of a headland sticking out into the ocean, with some waves (drawn as black lines representing the wave crests) approaching from the north. Draw continuing wave crests as the waves move in towards the coast and as they refract.
5 11. In the tide charts to the right, circle and label one example of each of the following: A. diurnal tide. B. mixed tide. C. neap tide. D. semidiurnal tide. E. spring tide. Note: In some cases, the answer is the whole graph; in other cases, the answer is part of one of the graphs. Label them carefully!
12. Describe the formation of Barrier Islands as discussed in The Beaches Are Moving video. What is the sequence of events and processes that occurred to give us these island features, and what happened to begin this process (and when)? ------(Note: several lines available for this on the actual test) ------
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Figure 1: Figure 2:
Figure 3: Figure 4:
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