Insert table chart text shape media comment collaborate format docume correlation with the magnetic time-scale the magnetic reversal time scale for the past 4.5 ma, which is primarily derived from careful work carried out on rocks of the continental crust, is shown in figure a3-8 4. correlate the peaks that you selected on the magnetic profiles with the various events described on this time scale, and record the dates of the features in the fourth row of the table above. note that points labelled a to e are the tips of the magnetic peaks. they correspond, therefore, with the centre points of the various positive (normal) magnetic events. for example, peak a represents the midpoint of the jaramillo event (as shown in blue), and the time should be half way between 0.92 and 0.97 ma, which is 0.945 ma, or 945,000 years. (5 points) chronology of magnetic field reversals for past 4.5 m. y. bruhnes (normal) matuyama (reversed) gauss (normal) gilbert reversed) (date m. y) 13 2 .97 t.เอเส'i 2 จ3,243: .: เม : ม)l@ r เพ) a. 2.02 3.03 .12 4.41 adapted from shea, j. h. (nov 1988). understanding magnetic anomalies and their significance. journal of geological education, 36(5), p298-305 figure a3-8. magnetic chronology time scale for the past 4.5 ma. 5. estimate the spreading rates of the antarctic ridge at 47.7° and 51.6°. divide the distances (km) by the number of years, and then convert those numbers to cm/year (multiply by 100,000), and put those numbers into rows 5 and 6 of the table above. determine the average rates at the two locations