124 



movement, and to outline areas of unstable seafloor sediments that are subject to 

 mass movements (submarine landslides) due to earthquake shock. Delineation 

 of broad target areas that contain favorable structures for production of oil and 

 gas. 



Geologic investigations in areas of rapid urban expansion in coastal southern 

 California and the San Francisco Bay region. Extension of large-scale (1 : 24,000) 

 mapping marginal to San Francisco Bay to cover the entire Bay, and accelera- 

 tion to provide geologic parameters ahead of both private and Federal engineering 

 construction to insure intelligent planning and vrise land use. 



Plam,ned 



Initiation of detailed geologic mapping of the southern California shelf to assess 

 the geologic hazards of this area which contains hundreds of offshore producing 

 oil wells, defense installations, and proposed coastal or offshore nuclear power 

 plants. 



Reconnaissance geologic mapping and geophysical studies on the outer conti- 

 nental shelf and slope off southern California to determine the seaward extent 

 of basins that produce petroleum in nearshore areas. 



Topical mineral resource evaluation to assess the phosphate deposits that occtli* 

 on many of the ridges on the southern California shelf with core drillings and 

 geoehemical studies to determine their grade, extent, and potential economic 

 value. 



Topical investigations on the nature of the interface between the continental 

 block and deep (Jcean floor, and relationship of the ocean fracture zones (Murray 

 and Mandocino) to the continental margin. 



ALASKA CONTINENTAL MARGIN 



This large shelf area (more than 500,000 square miles) contains known placer 

 deposits of gold, tin, and platinum, and also has an impressive known and poten- 

 tial petroleum reserve. The Geological Survey has led in the collection of onland 

 and marine geologic data in this area, and remains in the forefront of these in- 

 vestigations. The projects include : 



Current 



Investigation of offshore placer deposits to establish their distributional and 

 depositional patterns, to examine their internal structure to facilitate extrac- 

 tion techniques, and to evaluate their economic potenial. iSudies are underway in 

 three areas : 1) Off Nome, where raised beaches have yielded more than 5 million 

 ounces of gold, five submerged gold-bearing beaches have been found and are 

 being studied in detail ; 2) the floor of the Bering Sea, where previous Geological 

 Survey studies have outlined now submerged beach ridges and river channels 

 that may have localized gold concentrations; and 3) in the Gulf of Alaska and 

 southeastern Alaska, where submerged beaches and drainageways lie offshore 

 from known gold deposits. 



Intermediate scale mapping of the nearshore shelf of the central Gulf of Alaska 

 to guide management and assessment of this area for which public leasing has 

 been scheduled. Mapping to the outer edge of this shelf and adjacent slope to pro- 

 vide information on petroleum potential. 



Planned 



Reconnaissance traverses, some to be done from submersibles beneath the 

 Arctic ice pack, to investigate and broadly assess the petroleum-bearing basin 

 off northern Alaska. 



Three large sedimentary basins recently discovered by the Geological Survey 

 on the Bering Shelf will receive more detailed studies to outline their size and 

 internal structure. 



Study of Aleutian Arc-Trench System and adjacent Pacific Ocean fioor to under- 

 stand their history and the mechanism by which earthquakes such as the 

 disastrous 1964 earthquake are generated. 



Continuation of cooperative investigations with ESSA and the Navy Oceano- 

 graphic Office on the Bering Shelf, and implementation of a formal U.S.-Soviet 

 cooi)erative marine geology research program on the Bering Shelf. Arctic studies 

 with the Coast Guard are planned. 



