Has a question about reconstructing the Pangaea. Using Magnetic clues?

Question

how can you reconstruct the pangaea by comparing the age of igneous rock found near the mid-ocean ridge with that of the igneous rock found father way from the ridge?, If the distance from a point on the coast of Africa to the Mid-Atlantic Ridge is approx. 2,400 km, calculate how long ago that point in africa was at or near the Mid-Atlantic Ridge.

I cant understand how to do this, I have the rest of the assigment done but this last question, does anyone else know???

Answer 1

you should find enough info here:

http://en.wikipedia.org/wiki/Plate_tecto...

2400 km is 24,000,000 cm

Average speed of continents drifting apart is 5 cm/year according to http://hypertextbook.com/facts/ZhenHuang...

So that gives you 48 million years ago, approximately......