196 



BULLAKD AND MASON 



[chap. 10 



40° 



35' 



RIDGE AND 

 TROUGH PROVINCE 



40° 



DEEP PLAIN OF 

 THE NORTH-EAST 



BAJA CALIFORNIA 

 SEAMOUNT PROVINCE 



X SEAMOUNTS 



130° 



125° 



Fig. 12a. Index map to Fig. 11a. The shaded areas are positive and the contour interval is 

 250 y. (After Mason and Raff, 1961, fig. 1.) 



