1. Q: Almost everyone knows that most of the Earth’s surface is covered in water. Where did all that water come from?
Link

2. Bathymetry
The study of the depth/topography of the floor of a body of water

3. SONAR Short for Sound Navigation and Ranging
Originally used for submarine detection during WWII
Used since to map ocean floor topography

4. BATHYMETRY OF THE OCEAN FLOOR
Structures on the ocean floor are mapped by SONAR -
sound navigation and ranging (echo sounding)
(speed of sound in H20)
depth = time x 1500 meters/sec
2 (round trip)
sea floor

5. Do Now: Sound travels at 1500 meters per second in water
Do Now: Sound travels at 1500 meters per second in water. How deep is the ocean bottom if the sonar signal is received 6 seconds after it was sent?
6 seconds there and back
1500 meters
= 4500 meters deep
1 second
2 trips

6. Do Now: Sound travels at 1500 meters per second in water
Do Now: Sound travels at 1500 meters per second in water. The Mariana trench is 10,809 meters deep. How long will it take for sound to travel from the surface of the water above and back? Show your work.
10,809 m one way
2 (RT)
1 second
= 14.4 sec
1500 meters

7. THE WORLD OCEAN Covers 71 % of the planet (59.4 % is seafloor)
Divided into major basins –
Atlantic (N & S), Pacific, Arctic, Indian, Southern
Pacific – largest & deepest

8. Continental Margin: the submerged outer edge of a continent
marks the transition between continent and ocean, composed
of shelf, slope & rise
a. continental shelf - underwater extension of the continent, most biologically productive area because of light availability
b. continental slope – sloping transition between the continent (granite) and the deep-ocean floor (basalt)
- sediments tumbling down the slope can form turbidity currents which cut submarine canyons (deep, V-shaped valley running perpendicular to the shoreline)
c. continental rise – wedge of sediments covering the joint between ocean crust and continental crust
Continental Margin
NOAA

10. JQ: Do any organisms use sonar? Explain
Also called Bio Sonar, many dolphins, toothed-whales, cave swiftlets, shrews, tenrecs
Link
Link

11. Do Now: At its deepest point, Greenwood Lake is approximately 60 feet deep. About how long would it take to receive a signal back from a sonar ping from a boat above that spot in the lake. Remember, sound travels at 1500 meters per second in water.

12. Ocean Basin Features:
a. abyssal plain - flat, featureless region similar to a desert; common in Atlantic and Indian Oceans, rare in the Pacific
b. abyssal hill - occur where sediment is not thick enough to cover
the underlying rock completely. Usually extinct volcanoes or small
formations of rock once extruded in molten form.
c. seamount - peaks of volcanic mountains (sea mountains, completely underwater)
d. guyot - submerged, inactive volcano flattened by erosion
e. island - seamounts extending out of the water. They differ from continents because they have no margins.
f. trenches – arc-shaped depression in the deep-ocean floor with very steep sides and flat sediment-filled bottoms, associated with subduction zones where
ocean crust is being recycled into the mantle

14. ABYSSAL PLAIN

16. TRENCH

17. Iceland is a large section of the MOR extending above the water.
Mt. Everest, at 29,000 ft., could fit into the Mariana trench and still be 7,000 ft. below sea level.
g. Mid-Ocean Ridge (MOR) - 40,000 mile long mountain range where new oceanic floor is being formed.
Divergent plate boundaries are found in all parts of the ocean - not just in the middle of the Atlantic.
NOAA
Iceland is a large section of the MOR extending above the water.

18. h. rift “valley” – down-dropped section of a MOR occurring at divergent plate boundaries, outpouring of magma creates new ocean floor
NASA
Oceanic bathymetry is very similar to continental topography except that continent features are smaller due to erosion

19. SONAR Lab

20. Question: Hypothesize at least two ways in which sonar might affect marine organisms