Geol.— Vol. I.] DAVIDSON— SUBMERGED VALLEYS. 89 



II. The Santa Catalina Submerged Valley. 



Although the great island of Santa Catalina reaches 2,110 

 feet elevation, and is cut near its western quarter by the 

 " great depression " nearly to the water, yet there are some 

 slight signs of a submerged valley on each side, pointing to 

 this depression. Deep water surrounds the island, the 

 lOO-fathom curve lying i)^ miles from shore and being 

 slightly closer to the northern shore than to the southern. 



The island, which is 18 miles long, is traversed east and 

 west by a great rocky ridge, whose crest keeps within ij^ 

 miles of the north shore. On the south side of this crest- 

 line, and on the larger part of the island, converging ridges 

 reach generally westward to a marked indentation in the 

 precipitous shore-line, and into this rock-bound cove the 

 head of a submerged valley intrudes, bringing the 25-fathom 

 curve within one third of a mile of the general curve of the 

 shore, and the 300-fathom line within 3^^ miles. On the 

 southeast side of this valley the 75-fathom plateau reaches 

 out 3^ miles. 



At 25 fathoms the bottom is fine sand; at 40 fathoms and 

 over, gray mud; green mud is found at 100 fathoms and 

 more. 



The geographical position of the head of the valley is: 



Latitude 33° 23' N., longitude 118" 29' W., and its gen- 

 eral direction seaward is west. 



There is no break in the uniform bottom between Ana- 

 capa and Santa Cruz Islands. 



12. The Santa Cruz Island Submerged Valley. 



The crest-line of the principal east and west axis of this 

 island, which is 21 miles long, reaches an elevation of 2,150 

 feet. The southern parallel ridge reaches less than 1,500 

 feet; off this south shore the soundings drop to 600 fathoms 

 in less than three miles. 



The channel between the islands of Santa Cruz and Santa 

 Rosa of the Santa Barbara group is nearly five miles wide, 



