Oceanography Unit 2 11th Grade

Question Answer
1. The edge of a continent where the land interacts with the ocean or the transition from land to deep sea, going from continental crust to oceanic crust. CONTINENTAL MARGIN
2. Continental margins are made up of what three sea floor features? CONTINENTAL SHELF
3. Active continental margins are active geological areas with subduction, volcanoes, and earthquakes. Give three characteristics of active continental margins. • Very narrow continental shelf that is less stable
• Very steep continental slope
• Little or no continental rise
4. Passive continental margins are non-geologically active areas. Give three characteristics of passive continental margins. • Wide continental shelves that are more stable
• Gradual sloping continental slope
• Well-developed continental rise
5. A gently sloping submerged plain surrounding all continents, that can be narrow or wide, and extends from the beach out to the “shelf break”. CONTINENTAL SHELF
6. Area where the seafloor drops steeply from the continental shelf to the ocean floor. CONTINENTAL SLOPE
7. Define continental rise. Area where sediments from continents pile up at the base of the continental slope.
8. Define submarine canyons. Steep V shaped cuts through the continental slope.
9. What causes submarine canyons? Turbidity currents or under sea mudslides (carve valleys into the shelf and slope creating deep sea fans).
10. What is the feature called that forms from the sediments deposited on the ocean floor during the creation of a submarine canyon? Deep Sea Fans
11. Small, submerged volcanic mountains that are taller than 1 km. Seamounts
12. Small, submerged volcanic mountains that are shorter than 1 km Abyssal Hills
13. Submerged volcanic mountains that rise above the ocean surface are called? Islands
14. What is a guyot? An eroded seamount island that has become flattened.
15. Long, narrow, steep depressions in the ocean floor. Ocean Trenches
16. Ocean trenches from at (_____________________)boundaries where one plate (____________________________________). convergent tectonic plate
moves under the other and disappears into the mantle.
17. Define abyssal plain. Vast, flat seafloor areas at a depth of 10,000 to 20,000 feet.
18. Describe a mid-ocean ridge. The largest single volcanic feature on the Earth. It is the site of focused volcanic activity.
19. Mid ocean ridges occur at (___________________) boundaries where two plates are(___________________________). divergent tectonic plate
moving away from each other.
20. A depression that forms at the crest of the mid ocean ridge. Rift Valley
21. Magma comes up out of the ______________, a crack in the sea floor, where new crust is continually being created. Rift
22. What are hydrothermal vents. Hot springs or geysers on oceanic ridges
23. What is another name for hydrothermal vents. Black smokers
24. Why were we surprised to find hydrothermal vent ecosystems? There is no light penetration, no photosynthesis only chemosynthesis
25. What is the source of energy for organisms in hydrothermal vent ecosystems? Chemosynthesis
26. What are transform faults? Unstable areas of midocean ridge where fractures can form when large sections of ridge slide past each other.
27. What are fracture zones? Areas of very rough, steep topography created from transform faults.
28. A complex mixture of chemicals that sustains a variety of plant and animal life. Ocean water
29. Ocean water is also referred to as _______________. Why? Salt Water
Because of the high quantity of dissolved salts it contains
30. What percentage of ocean water is made up of water molecules?
What percentage of ocean water is made up of salts and other dissolved substances?
water molecules – 96.5%
salts and other dissolved substances – 3.5%
31. List the three main types of dissolved substances. Small particles of matter – (sediments, trash)
Small organisms – (plankton)
Dissolved gases – (nitrogen, oxygen, carbon dioxide)
32. Name the three principle dissolved gases in ocean water. nitrogen, oxygen, carbon dioxide

33. List the six most abundant elements in sea water.

Chlorine, sodium, sulfur, magnesium, calcium, potassium

34. List the properties of seawater. • Higher boiling point
• Lower freezing point
• Creates osmotic pressure
• Electrically conductive
• Decreases heat capacity
• Slower evaporation
35. The measure of the amount of dissolved substances in water and is measured in parts per thousand. Salinity
36. The average salinity of seawater is _____________________. 35 (0/00)
37. Define halocline. A layer of water where the salinity changes rapidly with depth.
38. How does the water cycle affect ocean salinity? Evaporation of seawater and freezing of seawater both increase the salinity of the ocean while precipitation of rain or snow, river runoff, melting of ice, groundwater flow to the ocean all decrease the salinity of the ocean.
39. Describe two ways that salt can be removed from seawater. Precipitation out of seawater in various chemical processes or when waves strike the beach (salt is removed with the sea spray).
40. Temperatures of ocean water can vary between ____________and ______________________. 2 degrees C and 28 degrees C
41. What factors can affect the temperature of ocean water? Latitude, season, ocean movement, and depth
42. Define thermocline. A layer of water where the temperature changes rapidly with depth.
43. How tightly packed molecules of a substance are in a specified space is called. Density
44. What three things can affect ocean water density? Salinity, Pressure, and Temperature
45. List the three density zones that the ocean is divided into. Surface Zone (Least Dense)
Pycnocline (Density increases with depth)
Deep Zone (Little changes in Density throughout this layer)
46. Define Pycnocline. A layer of water where the density changes rapidly with depth.
47. What is pH? The measure of H+ ions in solution
48. What is the range of the pH scale? Scale of 0 – 14
49. Where do acids and bases fall on the pH scale? 7 is neutral.
Above 7 is Basic
Below 7 is Acidic
50. Ocean water has a pH of ______________________. 7.8 – 8.3
51. _____________________help maintain stable pH levels Buffers
52. Name two buffers in seawater. Bicarbonate and carbonate

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