360 University of California Publications in Geology [Vol. ll 



ocean there should be any variation in sedimentation which would 

 produce such a regular banding. No evidence has ever been discovered 

 during the examination of many specimens of red clay and radiolarian 

 ooze, brought up in sounding tubes, of any such rhythmic alternation of 

 these two deposits. 



Possibility that Red Shales may be Bed Muds. — If the red clay be 

 eliminated as a possibility, the only other red formation known in the 

 deep sea, likely to be associated with radiolarian ooze, is the red mud 

 of terrigenous origin. This is deposited off the shores of tropical lands, 

 where conditions of oxidation predominate over those of reduction and 

 where the amount of organic matter in the mud on the sea bottom is 

 insufficient to reduce to sulphide form the iron oxide, brought down 

 by the rivers. It is conceivable that in an ocean deep, close enough to 

 shore, there might be alternations of terrigenous mud with radiolarian 

 ooze. It is a remarkable fact that the greatest oceanic depths are com- 

 paratively near land masses. The deeps off the west coast of South 

 America, the Aleutian Islands, the Kurile Islands and Japan, the 

 Philippines, the Ladrone Islands, the Pelew Islands, between the Solo- 

 mon Islands and New Pomerania, and to the north of New Zealand, 124 

 are examples in point. Agassiz 125 states that along the whole Atlantic 

 Coast from the Bahamas to St. Thomas, the line between the conti- 

 nental curve and the 2000 fathom line is nowhere greater than fifteen 

 miles distant from the shore. 



In view of these facts, there is nothing contradictory in the idea 

 of radiolarian oozes intermixed with red muds of terrigenous origin. 

 Off the west coast of Central America, at the present time, radiolarian 

 oozes occur in many places within 100 miles of the shore line. Here 

 they are deposited just outside an area of blue mud, which differs 

 from red mud only in that the state of oxidation of the iron is dif- 

 ferent. Analyses of the red muds agree more closely with the analyses 

 of the Franciscan shale partings than do analyses of red clay, though 

 here again the silica of red muds is lower and alumina is higher than 

 the content of the same elements in the Franciscan shale partings. 



Doctrine of Permanence of Ocean Basins. — The idea that radio- 

 larian cherts may be deep sea deposits has an important bearing on 

 the geological doctrine of the permanence of ocean basins. This doc- 

 trine is based, in part, upon the idea expressed by Murray and others, 

 that nothing is known in the continents which can be regarded as the 

 equivalent of the abyssal deposits. In so far as it is based on this 



124 Murray and Hjort, The Depths of the Ocean, p. 137, London, 1912. 



125 Op. cit., vol. 1, p. 143. 



