strength and direction of longshore currents at the Stinson Beacli State Park and at Bolinas 

 were started in May 1968, and continued for about 2 years at Stinson Beacli and 1 year at 

 Bolinas. The observations for 1968 have been published by CERC. (Szuwalski, 1970.) 

 Printouts of the complete records are available upon request. 



6. Littoral Transport. Littoral transport is defined as the movement of material in the 

 littoral zone by the wave-generated littoral currents. In 1965, an 80-mile reach of the central 

 California coast, extending from the mouth of the Russian River in the north to Half Moon 

 Bay in the soutli (Fig. 1), was studied for the characteristics of sediment movement in the 

 nearshore zone. From the results of man) beach and offshore sediment samples and other 

 information, several techniques were utilized in appraising the nature of sediment movement 

 along tliis coastline. The following were studied: (a) the physical nature of the coastline 

 from a consideration of the prevailing wave energy, (b) the distribution of light and heavy 

 minerals and their sources, (e) the use as tracers of certain naturally radioactive minerals, 

 and (d) the sedimentation experience at harbors where both natural and stabilized entrances 

 exist. It was concluded from these studies that the transport of nearshore sediments in this 

 region (which includes Bolinas Bay) is relatively small. (Johnson, 1965.) 



The only actual measurements of sediment movement in Bolinas Bay were a limited 

 number of observations on littoral drift made by the USGS using fluorescent-dyed sand at 

 three beach sites in the Bay. (Ritter, 1969.) Other data providing information on the general 

 movement of sediment in the entire Bolinas Bay resulted from the use of heavy minerals as 

 tracers. (Wilde, et al., 1969; Wilde and Yancey, 1970.) 



7. Bottom Sediments. The mechanical and mineralogical characteristics of beach and 

 offshore sediments in Bolinas Bay have been under investigation for several years by the 

 University of California on a project sponsored by CERC. (Moore, 1965; Isselhardt, et al., 

 1968 and 1969; Wilde, et al., 1969.) 



8. Tidal Relationships. The reference tide station for central California is the National 

 Ocean Survey (NOS) (formerly USC&GS) gage located at The Presidio, San Francisco. 

 Lower low water datum at this station is based on miscellaneous observations prior to 1907, 

 and adopted as standard in March, 1907. Elevations of other tide planes referred to this 

 datum are based on the 19 years of records, 1941—59. The USC&GS operated a tide gage 

 for a short period at Bolinas (probably immediately inside the Lagoon entrance) and 

 apparently used these data in calculating the difference in the time and height of tides at 

 Bolinas Bay and Bolinas Lagoon with respect to The Presidio, San Francisco. The 1972 NOS 

 Tide Tables for the west coast of North and South America give the tidal differences shown 

 in Table 2. Additional statistical data on tidal planes at San Francisco, Bolinas Bay, and 

 Bolinas Lagoon are presented in Table 3. 



9. Surveys of Beaches and Bottom. As previously mentioned, several beach and bottom 

 surveys were conducted over the last few years by various agencies to determine the 

 hydrography in both Bolinas Bay and Bolinas Lagoon, and to evaluate seasonal changes of 

 the shoreline in this area. Details of these surveys follow: 



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