334 



IIKK/.KN AND LAUGHTON 



|(HAr. 14 



500 



PRECISION DEPTH RECORDER PROFILES OF 

 THE PUERTO RICO TRENCH 



50-1 VERTICAL EXAGGERATION 



4500 



Fi«. 17. Two profiles of the rueito KicO Trench Abyssal Plain. (Alter Ewing and Heezen, 

 195.5.) 



1948, similar features have been reported in the Middle America Trench 

 (Fisher. 1954), the Kurile-Kamchatka Trench (Udintsev, 1955) and the Peru- 

 Chile Trench (Zeigler et al., 1957). Two trench plains are known in the Puerto 

 Rico Trench (Fig. 17). The smaller one occupies a basin south of a median ridge 

 and the larger one lies along the deep axis of the trench (Fig. 18). They range in 

 width from 1 or 2 mi to about 12 mi. Sediment cores taken in the trench plain 



