Name ___________________________________
FIS
Date _______
Block ______
The Seafloor Map
Oceanographers know, with sonar, how fast sound waves travel in water. Thus, they know how far the
waves travel during their round trip to the surface. Half this distance is the depth of the ocean at that spot. The
formula to find the ocean floor depth is:
D = 1/2 t x v
(t = time, v = velocity of sound in water = 1454 m/s)
The table below gives you some sonar sounding data. Calculate the ocean floor depth for each
sounding and then plot these depths on the graph below. Smoothly connect the depth points and you will have
a cross-sectional map of the South Atlantic Ocean floor.
Station
Time for the signal
to return (s)
Depth (m)
Station
Time for the signal
to return (s)
1
6
(0.5 x 6 x 1454) = 4362
6
2.4
2
5.2
7
4
3
4
8
5.2
4
2.4
9
6
5
3.2
(over)
Depth (m)
Under the profile line in the first & last column shade that area lightly with grey.
This represents the ____________________ crust.
Under the profile line between the lines labeled 1-4, and 6-9, color this area with a brown.
This represents the _____________________ crust.
Shade the remaining area under the profile line with a red. This represents the
____________________ ridge, where the new seafloor is forming.
Shade the area above the profile line in blue for the ocean.
Analysis:
1. What do we call the point from which oceanographers measure depth (the 0 depth mark)?
2. At which station(s) is the ocean deepest?
3. At which station(s) is the ocean most shallow?
4. What large ocean floor feature is evident in the cross-sectional map? (hint: it's in the middle)
5. At station #5, this is where new seafloor is made. What station numbers would you expect to find the oldest
crust?
LAYERS OF THE EARTH Review Q’s
1. Where is the densest material in the Earth, the Crust or the Core?
2. The crust of the earth is broken into many pieces called
3. This is the part of the mantle that flows and moves the plates of the Earth.
4. This is the largest layer of the earth: ________________________
5. _______________________ are caused by very hot material of the mantle rising, cooling, sinking then
heating, rising and repeating the cycle over and over.
6. Why is the inner core solid?