CONTINENTAL TERRACES AND SUBMARINE VALLEYS I55 



FIGURE 82. MAP OF SUBMARINE CANYONS OFF CALIFORNIA. AFTER 

 H. W. MURRAY AND THE UNITED STATES COAST AND GEODETIC SURVEY. 



now be kept open and not slowly filled with sand and mud as 

 in the case of the canyons oil the east coast of the United States. 



Summary 



Looking back, we see that the Glacial-control hypothesis 

 covers the essential facts, which may be listed as follows: 

 (1) the comparative youth of the topography; (2) its world- 

 wide planetary distribution; (3) the similarity of the conti- 

 nental slopes to the gullied hill-sides on land; (4) the evidence 



