101 



present survey, but Schupp (1953) studied the gravel that 

 periodically washes up on the beach in this area so the 

 general lithology of the material is known. 



Siliceous and non-siliceous shales were the most abundant 

 rocks recovered from the offshore area, followed in importance 

 by mudstones, siltstones, and sandstones. Emery and Shepard 

 (1945) recovered limestone and red rhyolite from Redondo 

 Canyon, and dredged conglomerate, rhyolite, andesite, and 

 granite from Santa Monica Canyon. They date the granite as 

 Jurassic (?) on its lithologic affinity to granite outcrops 

 in the Santa Monica Mountains. At least one sample collected 

 by the Hancock Foundation (station 4321) was positively identi- 

 fied as being Upper Miocene in age (Lower Mohnian) and several 

 other samples were dated as probable Miocene, Emery and 

 Shepard also found rocks containing Foraminifera of Miocene, 

 Pliocene, and Pleistocene age .in a conglomerate dredged from 

 Santa Monica Canyon. 



A large amount of shale (both siliceous and nonsiliceous), 

 mudstone, and siltstone was dredged from the rock and gravel 

 area on the outer shelf. Many of the fragments were nearly 

 covered, or bored through, by organisms such as pholads and 

 echinoids. Few of the sedimentary rocks had diagnostic Forami- 

 nifera. Since pholads and most other rock boring organisms 

 are generally restricted to the littoral zone, or relatively 

 shallow water, where current and wave action is quite vigorous, 

 the abundance of borings indicates that this area was at one 

 time close to sea level. 



