USGS - science for a changing world

Pacific Coastal and Marine Science Center

California Seafloor Mapping Program

Map-Set Publication

USGS and COPC are supporting development of peer-reviewed map sets for California’s mainland State Waters. Each map set contains 10 downloadable pdf map sheets (most at 1:24,000) for a selected coastal “block.” Map sheets show bathymetry, backscatter, perspective views, seafloor “character” (video-supervised automated classification of bathymetry and backscatter), groundtruthing imagery, potential habitats, seismic-reflection profiles, sediment distribution and thickness, and onshore-offshore geology. Some map sets include additional thematic sheets that highlight detailed geomorphology, predicted distribution of benthic macro-invertebrates, and natural offshore hydrocarbon seepage. These map publications also include an explanatory pamphlet and a set of digital data layers (about 20 to 25 per mapping block) that are compiled in a USGS CSMP Data Catalog (Golden, 2014).

Consult the Progress page for the latest news on publications. As of 10/1/14, six map sets have been published; eleven additional map sets are in the USGS publication queue (data are already published in the Data Catalog); and five additional map sets are in peer review. This first phase of map-set publications covers 27 percent of California’s mainland coast. Each map set represents a large collaborative effort (42 co-authors have been involved) representing federal, state, academic, and private-sector partners. The examples shown below are from the “Hueneme Canyon and Vicinity” map set.

color bathy
Sheet 1Full-size(21.5 MB)
gray-scale bathy
Sheet 2Full-size(19.2 MB)

Colored Shaded-Relief Bathymetry (Sheet 1)

Shaded-Relief Bathymetry – gray-scale (Sheet 2)

Fine-scale seafloor geomorphology is revealed in both gray and color-coded shaded-relief digital elevation models (DEM) created from multibeam sonar bathymetry data and bathymetric LiDAR. The gray shaded-relief map (Sheet 2) is used to take advantage of the human eye's ability to discern finer detail in black and white versus color imagery, while the color-coded shaded-relief map (Sheet 1) reveals detailed depth information.

Sheet 3Full-size(26.1 MB)

Acoustic Backscatter (Sheet 3)

Gray-scale backscatter maps show the intensity of an acoustic pulse reflected off the seafloor and recorded by the multibeam transducer. Brighter tones indicate a strong acoustic return (typically a hard bottom consisting of rock or coarse sand) whereas darker tones indicate a weaker acoustic return (typically fine sand or mud). These data aid in the seafloor character, geology, and habitat interpretations because the signal is partially influenced by the composition and roughness of the seafloor.

Sheet 4Full-size(21.6 MB)

Data Integration and Visualization (Sheet 4)

Perspective views are three-dimensional representations of the seafloor that highlight and reveal details of important geomorphic features such as submarine canyons, rocky reefs, or scour depressions. Block diagrams that merge the bathymetry data with seismic-reflection profiles provide insights on the controls of subsurface structure on seafloor morphology. Video-mosaic images created from digital seafloor video display the geologic complexity (rock, sand, and mud; see Sheet 10) and biologic complexity of the seafloor.

seafloor character
Sheet 5Full-size(28.8 MB)

Seafloor Character (Sheet 5)

The seafloor character map is produced using video-supervised maximum likelihood classification of the bathymetry and backscatter (intensity of return) signals from sonar systems (Cochrane, 2008). Derivative roughness (rugosity) and backscatter intensity were used as variants in the classification. The substrate classes are then divided into the California Marine Life Protection Act depth zones.

ground-truth studies map
Sheet 6Full-size(19.3 MB)

Ground-Truth Studies (Sheet 6)

This sheet shows the seafloor character map, tracklines of ground-truthing camera transects, and images from both still and video cameras collected along the tracklines. This imagery is used to validate and inform seafloor character (Sheet 5), potential benthic habitat (Sheet 7), and geologic maps (Sheet 10).

habitat map
Sheet 7Full-size(21.1 MB)

Potential Marine Benthic Habitats (Sheet 7)

The map on Sheet 7 shows “potential” marine benthic habitats, representing a substrate type, geomorphology, seafloor process, or any other attribute that may provide a habitat for a specific species or assemblage of organisms.

ground truth sheet
Sheet 8Full-size(25 MB)

Seismic-Reflection Profiles (Sheet 8)

The seismic-reflection profiles compiled on Sheet 8 provide a third dimension, depth, to complement the surficial seafloor-mapping data presented on Sheets 1 through 7. The seismic-reflection profiles provide information on sediment character, distribution, and thickness, as well as potential geologic hazards, including active faults, areas prone to strong ground motion, and tsunamigenic slope failures.

isopach sheet
Sheet 9Full-size(20.9 MB)

Local and Regional Shallow-Subsurface Geology and Structure (Sheet 9)

Maps on Sheet 9 (largely derived from seismic-reflection profiles) show the distribution and thickness of the uppermost sediment unit; the depth-to-base of this uppermost unit; and both the local and regional distribution of faults and earthquake epicenters.

onshore/offshore geology/geomorphology
Sheet 10Full-size(19.3 MB)

Offshore and Onshore Geology and Geomorphology (Sheet 10)

Merged offshore-onshore geologic map shows and describes (age, composition) different geologic units, contacts and relationships between units, geologic structure (faults and folds), and geomorphic landforms. These maps are collaborations between the USGS (offshore mapping) and the California Geological Survey (onshore mapping).

onshore/offshore geology/geomorphology
Sheet 11Full-size(19.3 MB)

Detailed Geology and Geomorphology (Sheet 11)

Important geologic and geomorphic details are shown on the geology, slope, and curvature maps on this sheet.

onshore/offshore geology/geomorphology
Sheet 12Full-size(25.1 MB)

Predicted Distribution of Benthic Macro-Invertebrates (Sheet 12)

Sheet 12 displays predictive models of occurrence for common benthic macro-invertebrate taxa and maps the probability of occurrence of these taxa in the Santa Barbara Channel. These models are based on real-time biological observations of all macro-organisms made during ground-truth surveys (Sheet 6).

For more information, contact Guy Cochrane or Sam Johnson.

Accessibility FOIA Privacy Policies and Notices logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: Laura Zink Torresan