Bed sediment samples were collected in south San Francisco Bay on two days in July 2020 to analyze for sediment grain size distributions. Sediment samples were collected from the R/V Snavely near pre-established U.S. Geological Survey instrument moorings using a Gomex or Ponar box corer that was subsampled by scraping the top 0.5 cm of the core. Data are provided in a comma-delimited values spreadsheet.

This section of the data release contains grain-size and total organic carbon (TOC) analyses of 174 samples taken from vibracores that were collected aboard the R/V Bold Horizon in 2018 on U.S. Geological Survey Field Activity 2018-638-FA offshore Oceanside to San Diego, southern California. The samples were analyzed for percent weight of grain size and total organic carbon. The samples were taken at approx. 50 cm intervals from (and including) the core-catcher, which represents the bottom of the core.

Sediment cores were collected from San Pablo Bay, in the Sacramento-San Joaquin Delta in California by the U.S. Geological Survey Pacific Coastal and Marine Science Center (PCMSC) during multiple surveys from 2011 to 2012. The cores were analyzed for grain-size distributions at the PCMSC sediment lab.

Fluvial sediment samples were collected from the lowermost reaches of 21 coastal watersheds in California, in order to characterize surficial grain size of river sediment from deposits that appeared to be recent based on field context. Samples were collected using a trowel to sample the uppermost 10 cm of sediment. Sampled locations included river-deposited sediment, upstream of tidal influence. Samples excluded coarse gravel and cobble grain sizes, if present. The watersheds selected for sampling have relatively little urban land use and no other recent data available on their fluvial sediment grain size. Sediment samples were analyzed for grain size at the U.S. Geological Survey (USGS) laboratory in Santa Cruz, California. The USGS gratefully acknowledges sampling permission granted by California State Parks.

This section of the data release contains grain-size and total organic carbon (TOC) analyses of 132 samples taken from vibracores that were collected aboard the R/V Bold Horizon in 2019 on U.S. Geological Survey Field Activity 2019-649-FA offshore San Francisco, California. The samples were analyzed for percent weight of grain size and total organic carbon. The samples were taken at approx. 50 cm intervals from (and including) the core-catcher, which represents the bottom of the core.

This dataset contains surface sediment grain size distributions derived from manual point counts of in situ seafloor images obtained with an underwater camera system in the lower Columbia River, Washington and Oregon, in 2021. The distributions derived from manual point counts were compared with results from an automated image processing technique to calibrate and validate the automated method used to quantify surface sediment grain size distributions in objective images. The surface sediment grain size distribution data derived from manual point counts are provided in comma-separated text format (point_count_distributions.csv) and should be compared with grain size distributions for the same set of images (dgs_calibration_validation.csv) derived from automated image processing that can be found in the "Surface sediment grain size distributions derived from automated image processing of in situ seafloor images from the lower Columbia River, Washington and Oregon, 2021" portion of the overall data release.

This dataset contains surface sediment grain size distributions derived from manual point counts of in situ seafloor images obtained with an underwater camera system in the lower Columbia River, Washington and Oregon, in 2021. The distributions derived from manual point counts were compared with results from an automated image processing technique to calibrate and validate the automated method used to quantify surface sediment grain size distributions in objective images. The surface sediment grain size distribution data derived from manual point counts are provided in comma-separated text format (point_count_distributions.csv) and should be compared with grain size distributions for the same set of images (dgs_calibration_validation.csv) derived from automated image processing that can be found in the "Surface sediment grain size distributions derived from automated image processing of in situ seafloor images from the lower Columbia River, Washington and Oregon, 2021" portion of the overall data release.

This data release presents sediment grain-size data from samples collected from core S3-15G, a 4.72-m long gravity core collected at a depth of 3,491 meters on the western levy of the Monterey Fan on May 31, 1978 (USGS Field Activity S-3-78-SC).

This data release presents sediment grain-size data from samples collected from core S3-15G, a 4.72-m long gravity core collected at a depth of 3,491 meters on the western levy of the Monterey Fan on May 31, 1978 (USGS Field Activity S-3-78-SC).

This data release includes grain-size measurements of sediment samples collected from the substrate surface and uppermost 10 cm of sediment deposits in the Klamath estuary, northern California. Samples were collected using a BMH-60 bed-material sampler deployed from a boat, or by hand trowel from subaerial or shallow-water (less than 0.5 m water depth) regions along the estuary margins and side channels. Sediment grain size was analyzed at the U.S. Geological Survey (USGS) laboratory in Santa Cruz, Calif. Particles coarser than 2 mm were sieved using a RO-TAP sieve shaker, and particles finer than 2 mm were analyzed with a Coulter laser particle-size analyzer (LPSA), after organic matter had been removed using a hydrogen peroxide solution. At some submerged locations where sampling was attempted, no sample was recovered. The field crew observed this occurring in places where the substrate was too coarse-grained to be collected by the bed-material sampler (cobbles), where large particles were embedded in finer (poorly sorted) matrix, and where sediment was covered by algal mats thick enough to prevent the sampler from accessing the sedimentary substrate. Locations where sampling was attempted but no sample was recovered are indicated in the ‘Comments’ column within the data spreadsheet. The sediment samples were collected under a Cultural Resources Management Permit issued by the Yurok Tribe, whose support the USGS acknowledges gratefully.