RECENT SEDIMENTS OF BOLINAS BAY, CALIFORNIA. PART C. INTERPRETATION AND SUMMARY OF RESULTS.
Abstract
Samples of marine sediments and shore rocks from Bolinas Bay, California, were analyzed for grain size and heavy mineral content. This work, part of a study of sediment transport off Central California, indicates: (1) heavy mineral assemblage is predominantly green hornblende with secondary amounts of hypersthene and augite. Nearshore glaucophane and jadeite occur in locally high concentrations. (2) Distribution pattern of the heavy minerals shows a tongue of high concentrations of minerals that have a granitic source extending northwest from the San Francisco Bar, flanked on the north and northeast by increasing landward concentrations of Franciscan metamorphic minerals. (3) The major source of heavy minerals is the San Francisco Bar. Secondary contributions come from Bolinas Lagoon and the adjacent cliffs. (4) Circulation in the bay is primarily counterclockwise; produced by a combination of wave refraction around Duxbury Reef and the tidal coast eddy current. Tidal influence, however, of Bolinas Lagoon is restricted to about 1 mile from the lagoon mouth. Circulation patterns in the bay greatly influence sediment distribution. (5) Annual sediment flux in Bolinas Bay is about 300,000 cubic yards; bottom sediments are apparently in quasi-equilibrium. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1969
- Accession Number
- AD0704694
Entities
People
- C. Isselhardt
- L. Osuch
- P. Wilde
- T. Yancey
Organizations
- University of California, Berkeley