Seafloor spreading rates

SEAFLOOR SPREADING RATES

How did scientists use their knowledge of seafloor spreading and magnetic field reversals to reconstruct Pangea. With this activity, you will be able to determine where a continent may have been located in the past.

Procedure:

1. 
   Study the magnetic field graph below. You will be working only with normal polarity readings which are the peaks above the baseline in the top half of the graph.
   
2. 
   Place the long edge of a ruler vertically on the graph so that it lines up with the center of peak 1 west of the Mid-Atlantic ridge and draw a line straight down so that it intersects with the distance and age on the bottom of the graph. Repeat this for peak 1 east of the ridge.
   
3. 
   Identify the distance from the west of the ridge and place the number on the table on the back. Do the same for the distance east of the ridge.
   
4. 
   Calculate the average distance for Peak 1 and put it on the table.
   
5. 
   Identify the age from the west of the ridge for Peak 1 and write the number on the table. Do the same for the age east of the ridge.
   
6. 
   Calculate the average age for Peak 1 and put it on the table.
   
7. 
   Repeat steps 2-7 for the remaining peaks.
   

8. 
   Calculate the movement in cm per year for the six pairs of peaks. Use the formula
   

1. 
   First convert km to cm and put the number on the table.
   

Answer the following questions:

1. 
   Calculate the average speed of movement at the Mid-Atlantic Ridge. ________________
   
2. 
   Looking at the graph, what can you say about the age of the igneous rock found near the mid-ocean ridge compared to that of igneous rock found near the continent?
   ________________________________________________________________________________________________________________________________________________________________________
   
3. 
   How could you use this method to reconstruct Pangaea? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
   
4. 
   What is causing the plates to move apart at the mid-Atlantic ridge? ________________________________________________________________________________________________________________________________________________________________________
   
5. 
   If the distance from a point of the coast of Africa to the Mid-Atlantic Ridge is 2400 km, calculate how long ago that point in Africa was at or near the Mid-Atlantic Ridge. Use your answer from question 1 to help you. ___________________________________________________________________________
   
6. 
   Do you think that this will continue for the next 100,000,000 years? Explain ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________