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University of California. 



[Vol. 2. 



scribed and figured by him occur within the area under considera- 

 tion. 



In explanation- of the origin of these submarine valleys on the 

 California coast, two views have been put forward by Pacific Coast 

 geologists — one that they are structural in origin, and the other 

 that they are submerged stream valleys. Neither of these views is 

 wholly satisfactory, especially in accounting for those valleys which 

 head close to the shore line, as the majority of them do. While 

 there can be little doubt that some of the valleys are due to crustal 

 deformation, it would seem that the majority are to be accounted 

 for in some other way — though it by no means follows that this 

 way is the submergence of stream valleys. Further, each valley 

 must be considered by itself, since the explanation for any one is 

 not necessarily the explanation for all. Probably a final and satis- 

 factory explanation can be given, if at all, only after a careful study 

 of the geology in the region about each one of the submarine 

 valleys. 



The northern group of islands is separated from the mainland 

 by the Santa Barbara Channel, the deepest part of which, forming 

 a basin-like depression, lies to the north of Santa Rosa Island, and 

 has a maximum depth of about 2,200 feet. To the west of that 

 depression a broad submarine ridge extends from San Miguel 

 Island northward toward Point Conception, the lowest part being 

 at a depth of about 1,450 feet. At the eastern end of the channel, 

 between Anacapa Island and San Buenaventura on the mainland, 

 and connecting the upper coastal platform with that of the islands, 

 though at a somewhat lower level, is another short submarine 

 ridge, whose lowest part, about one-third of the distance between 

 the islands and the mainland, shows a depth of water of only 700 

 feet. As the passages between the islands themselves are in no 

 case of greater depth than 200 feet, an elevation of the coast of a 

 little more than 700 feet would connect the entire group with the 

 mainland. 



The submarine ridges across either end of the Santa Barbara 

 Channel have doubtless been formed through deposition due to 

 conflicting currents at these points. If caused in this way, both 

 ridges (especially the eastern one) are now and must have been in 



