Name___________________________________
Group________________________________
Seafloor Features Study Guide
1. What is a lead line? What early evidence do we have of soundings being taken with lead lines?
2. Who published the first bathymetric map in 1854?
3. Who developed the first echo sounder in 1922? Who was the first to detect the Mid-Atlantic Ridge with an echo
sounder in the 1950’s?
4. How do echo sounders work?
5. Describe the difference between what can be detected with high frequency sounds versus what can be detected
with low frequency sounds.
6. Explain the deep scattering layer or “false bottom” readings.
7. List 5 different types of acoustic technologies used to measure the seafloor features. Which one is the most
precise? Which ones are good for “seeing” sub-bottom features?
8. What is the name of the most comprehensive bathymetric map ever made (to date)?
9. How fast does sound travel in air? How fast does sound travel in seawater?
10. How does the speed of sound change with temperature? With salinity? With depth (pressure)?
11. Explain the SOFAR channel. What happens to sound in this channel? Where is the channel located?
12. What has the SOFAR channel been utilized for? (You should explain the ATOC, SOSUS, and scientific research.)
13. Define/describe the Lithosphere. Define/describe the Athenosphere.
14. What does the concept of isostasy explain?
15. According to isostatic equilibrium, taller land masses will have ________________ (shallower/deeper) roots.
16. As the surface of a mountain accumulates sediment, the “roots” in the mantle
________________________________ (shrink up/increase depth).
17. As the top of a mountain erodes down, the “roots” in the mantle _____________________(shrink up/increase
depth).
18. Define the Continental Margin.
19. Describe the differences between Active Margins and Passive Margins. Where are each type of margins found?
List examples.
20. Draw a continental margin with a Continental Shelf, Continental Slope, and Continental Rise. Label each.
21. What is a submarine canyon? How are these canyons formed? Give an example.
22. What are turbidity currents? Explain tubidites?
23. Continental rises are not typically found on active margins? Why not? What seafloor feature is typically
associated with an active margin?
24. Why is the North Carolina continental margin so different from the California continental margin?
25. What is the abyssal plain?
26. Explain the difference between abyssal hills, seamounts, guyots, and islands.
27. Where are trenches found? What is the deepest trench? What is the longest trench? What are the only two
trenches in the Atlantic?
28. What are hydrothermal vents? What is the difference between “black smokers” and “white smokers”?
29. Why are hydrothermal vents biologically significant? Can photosynthesis occur here?
30. List the 5 oceans that comprise the World Ocean. Which one is the largest? Which one is the smallest and
shallowest?