Name ______date ______

Lab: Sonar Mapping of the Ocean Floor

Background Information: Mapping the ocean floor must be done by indirect observation. One current method involves bouncing a sonar signal off the ocean floor and measuring the length of time this signal it takes to return. This length can be translated into distance.

Distance = Speed of Sound X Time 2 In this lab, you will be making indirect observations using a wooden rod as the "sonar signal." The type of map you will create that shows the features on the ocean floor is called a Bathymetric lab.

Materials per Team:

 Bucket/”ocean Floor”  Wooden "sounding " rod  Metal grid  Grid graph paper  Metric ruler  tape  Color pencils

Procedure: 1. Place the metal grid over the top of the bucket and tape it in place. 2. Place the wooden rod into one of the holes in the top of the grid. Mark the "depth" (length of the rod). 3. Measure to the nearest centimeter the distance from the lid to where the wooden rod touched the bottom of the box (ocean floor). 3. Subtract your depth measurement from the total depth of the box. 4. Record your measurements on the grid graph paper. 5. Draw lines that connect all the soundings of the same depth. 6. Color in your depth contours by using light blue for the most shallow, then darker and darker shades of blue indicating deeper depths. Draw a key to your colors. 7. Check your map with the teacher and then drain the water from your bucket and compare your ocean floor bottom to the actual "floor." 8. Cut out the label tags of ocean floor features that you have and glue them to your map. Note: You may not have all the features on the list. 9. Complete your analysis. Analysis

1. Which features are on your ocean floor and shown by your bathymetric map?

2. How does your bathymetric map compare to the actual model of the ocean floor? Did you miss any features? Why?

3. Do you think oceanographers have similar problems during their investigations? Explain.

4. How could you have improved the accuracy of your results?

5. If you were the captain of a fishing boat, What are two reasons for studying a nautical chart with bathymetric information before fishing.? Labels for Ocean floor Bathymetric map

Continental shelf

Continental slope

Seamount

Volcanic island

Abyssal plain

Oceanic trench

Submarine canyon

Guyot

Mid-ocean ridge