Title GEOLOGY OF THE CONTINENTAL TERRACE OFF THE CENTRAL COAST

Abstract approved (Major prfessor) The continental terrace west of Oregon between 43O 5OtN and 44'40 ' N latitude is 50 to 55 miles wide. It consists of a continental shelf, 16 to 35 miles wide, and a continental slope, 16 to 37 miles wide. The eastern portion of the shelf is a smooth, sediment covered area that slopes very gently west. The western portion of the shelf contains four rocky bank areas. The banks are topographically ir-regular and appear to be of structural origin. West of the banks the shelf edge occurs at depths of 71 to 90 fathoms. The continental slope extends from the edge of the shelf to the abyssal plain at depths of 1530 to 1610 fathoms. A smooth upper slope of less than three degrees extending to depths of 117 to 250 fathoms occurs north and south of Heceta Bank. West of Heceta Bank the up-per slope is formed by a scarp that slopes 10 ' to. 16 ° to 560 to 72