Paleomagnetic determinations were conducted on three suites of rocks from the Bree Creek Quadrangle. A sandstone unit within the 60 Ma Edoras Formation yielded average inclinations of 46°; tuffaceous beds within the 38 Ma Dimrill Dale Diatomite yielded inclinations of 33°; and the Rohan Tuff (18 Ma) yielded an average inclination of 25°. Independent evidence suggests that the Bree Creek Quadrangle remained north of the equator for its entire history.

1. Calculate the starting and ending latitudes for the block of continental crust on which this quadrangle lies for each of the two stages of movement.

2. Calculate the minimum rate of movement of the block for each stage of movement.

3. Explain why your answer to question 2 is a minimum.

4. Use Fig. G-60 to sketch figures showing: 

(1) Apparent motion of the paleomagnetic pole in a ‘‘fixed’’ plate reference frame, and 

(2) Latitudinal motion of the plate with respect to the fixed pole.

Fig. G-60