USGS CMG P-1-89-SF Metadata

To study the southern and northern parts of the bay in a
manner analogous to that of Rubin and McCulloch (1979) for central
SF Bay. To study the surficial characteristics and composition of
the bay floor, and how physical processes both form and modify it
into different morphologies.

Tracklines were plotted on overlays of the 1:40,000-scale National Ocean Survey 
bathymetric maps of San Francisco Bay (Sheets 1, 2, 3). Maps of the distribution 
of bedforms.

Reconnaissance investigation characterizes the surficial
morphology of the bay floor as revealed by side-scan sonar imaging
and high-resolution bathymetry and deduces the general nature of
sedimentation, bedload sediment transport directions, and areas of
depostion versus erosion. Results should apply to current issues
involving sedimentation, dredging, pollution, and the disposal of
dredge spoils in the San Francisco Bay system and the highly
developed urban areas that border it.

Field work for this study was conducted using the USGS Water
Resources Divsion Research Vessel Polaris. Side-scan sonar profiles
were collected using a Klein system operated at a frequency of
either 100 kHz (South Bay or 500 kHz (North Bay). This system is
comprised of a graphic recorder and towfish that can be operated at
varying frequencies and slant ranges. In general, slant ranges of
100 m (200-m swath) or 150 m (300-m swath) were used for optimum
resolution of bottom features on the bay floor. Towing speed
averaged 7.4 km/hour, although this varied greatly with tidal current
speed and direction as well as local wind regime. No attempt was
made to acqurie overlapping side-scan sonar images.

An Innerspace fathometer was used to acquire high resolution
bathymetry. This system operated at a frequency of 200 kHz with a
hull-mounted transducer. The bathymetry was not corrected for tidal
elevation. Navigation was obatined with a shipboard Raytheon precision
radar. Fixes were plotted every 5 min. and correspond to the event
marks on the side-scan sonar and fathometer records.

The floor of South and North San Francisco Bay is characterized by
five surficial bottom types based on a reconnaissance survey using
side-scan sonar and a fathometer. The five bottom types are
1) furrows,
2) lineations,
3) sand waves,
4) tonal patches,
5) featureless.