Fig. 26

Tidal density plume, San Francisco, California. a Location map showing the mouth of the San Francisco Bay with the Pacific Ocean at the Golden Gate Bridge (Circle); b Image showing a field of giant tidal sand waves and other bedforms at the mouth of San Francisco Bay. The view is from the northwest toward the Golden Gate Bridge (seen in the background), which is approximately 2-km long. More than 40 large (greater than 50-m wavelength) sand waves were mapped, with crest-to-crest lengths of as much as 220 m and heights of as much as 10 m. This computer-generated image by Patrick Barnard of sand waves is based on high-resolution multibeam imaging of the seafloor using research vessel VenTresca by the CSUMB Seafloor Mapping Laboratory. Vertical exaggeration: 3X. Geological details of the setting and sand waves are discussed by Barnard et al. (2006). The land was imaged using digital orthophotos draped over a U.S. Geological Survey digital elevation model. The Golden Gate Bridge model is courtesy of IVS 3D©. Image courtesy of USGS, http://soundwaves.usgs.gov/2006/09/ViewtoGateHGLG.jpg. Accessed July 14, 2011. See also Bouma et al. (1977) for examples from Alaska; c Satellite image showing tidal lobate plume at the mouth (circle; Golden Gate Bridg) of the San Francisco Bay. Image credit: NASA: The Operational Land Imager (OLI) on Landsat 8. Image acquired on March 1, 2017. Additional labels by G. Shanmugam