California State Waters Map Series-Offshore of Point Reyes, California

Open-File Report 2015-1114
By: , and 
Edited by: Janet T. Watt and Susan A. Cochran

Links

  • More information: USGS Index Page
  • Document: Pamphlet (1.1 MB pdf)
  • Plates:
    • Sheet 1 (14.6 MB pdf) Colored Shaded-Relief Bathymetry, Offshore of Point Reyes Map Area, California By Peter Dartnell and Rikk G. Kvitek
    • Sheet 2 (18.7 MB pdf) Shaded-Relief Bathymetry, Offshore of Point Reyes Map Area, California By Peter Dartnell and Rikk G. Kvitek
    • Sheet 3 (23.9 MB pdf) Acoustic Backscatter, Offshore of Point Reyes Map Area, California By Peter Dartnell, Mercedes D. Erdey, and Rikk G. Kvitek
    • Sheet 4 (16.2 MB pdf) Data Integration and Visualization, Offshore of Point Reyes Map Area, California By Peter Dartnell
    • Sheet 5 (25 MB pdf) Seafloor Character, Offshore of Point Reyes Map Area, California By Mercedes D. Erdey and Guy R. Cochrane
    • Sheet 6 (27.5 MB pdf) Ground-Truth Studies, Offshore of Point Reyes Map Area, California By Nadine E. Golden, Guy R. Cochrane, and Lisa M. Krigsman
    • Sheet 7 (6.9 MD pdf) Potential Marine Benthic Habitats, Offshore of Point Reyes Map Area, California By Charles A. Endris, H. Gary Greene, Bryan E. Dieter, Erik N. Lowe, and Mercedes D. Erdey
    • Sheet 8 (33.3 MB pdf) Seismic-Reflection Profiles, Offshore of Point Reyes Map Area, California By Janet T. Watt, Samuel Y. Johnson, John L. Chin, and Ray W. Sliter
    • Sheet 9 (9.4 MB pdf) Local (Offshore of Point Reyes Map Area) and Regional (Offshore from Salt Point to Drakes Bay) Shallow-Subsurface Geology and Structure, California By Janet T. Watt, Samuel Y. Johnson, Stephen R. Hartwell, and Ray W. Sliter
    • Sheet 10 (17 MB pdf) Offshore and Onshore Geology and Geomorphology, Offshore of Point Reyes Map Area, California By Janet T. Watt, Michael W. Manson, and H. Gary Greene
  • Companion File: Data Catalog-Offshore of Point Reyes, California Each GIS data file is listed with a brief description, a small image, and links to the metadata files and the downloadable data files.
  • Metadata: Metadata
  • Download citation as: RIS | Dublin Core

Abstract

This publication about the Offshore of Point Reyes map area includes ten map sheets that contain explanatory text, in addition to this descriptive pamphlet and a data catalog of geographic information system (GIS) files. Sheets 1, 2, and 3 combine data from four different sonar surveys to generate comprehensive high-resolution bathymetry and acoustic-backscatter coverage of the map area. These data reveal a range of physiographic features (highlighted in the perspective views on sheet 4) such as the flat, sediment-covered seafloor in Drakes Bay, as well as abundant “scour depressions” on the Bodega Head–Tomales Point shelf (see sheet 9) and local, tectonically controlled bedrock uplifts. To validate geological and biological interpretations of the sonar data shown in sheets 1, 2, and 3, the U.S. Geological Survey towed a camera sled over specific offshore locations, collecting both video and photographic imagery; these “ground-truth” surveying data are summarized on sheet 6. Sheet 5 is a “seafloor character” map, which classifies the seafloor on the basis of depth, slope, rugosity (ruggedness), and backscatter intensity and which is further informed by the ground-truth-survey imagery. Sheet 7 is a map of “potential habitats,” which are delineated on the basis of substrate type, geomorphology, seafloor process, or other attributes that may provide a habitat for a specific species or assemblage of organisms. Sheet 8 compiles representative seismic-reflection profiles from the map area, providing information on the subsurface stratigraphy and structure of the map area. Sheet 9 shows the distribution and thickness of young sediment (deposited over the last about 21,000 years, during the most recent sea-level rise) in both the map area and the larger Salt Point to Drakes Bay region, interpreted on the basis of the seismic-reflection data, and it identifies the Offshore of Point Reyes map area as lying within the Bodega Head–Tomales Point shelf, Point Reyes bar, and Bolinas shelf domains. Sheet 10 is a geologic map that merges onshore geologic mapping (compiled from existing maps by the California Geological Survey) and new offshore geologic mapping that is based on integration of high-resolution bathymetry and backscatter imagery (sheets 1, 2, 3), seafloor-sediment and rock samples (Reid and others, 2006), digital camera and video imagery (sheet 6), and high-resolution seismic-reflection profiles (sheet 8), as well as aerial-photographic interpretation of nearshore areas. The information provided by the map sheets, pamphlet, and data catalog have a broad range of applications. High-resolution bathymetry, acoustic backscatter, ground-truth-surveying imagery, and habitat mapping all contribute to habitat characterization and ecosystem-based management by providing essential data for delineation of marine protected areas and ecosystem restoration. Many of the maps provide high-resolution baselines that will be critical for monitoring environmental change associated with climate change, coastal development, or other forcings. High-resolution bathymetry is a critical component for modeling coastal flooding caused by storms and tsunamis, as well as inundation associated with longer term sea-level rise. Seismic-reflection and bathymetric data help characterize earthquake and tsunami sources, critical for natural-hazard assessments of coastal zones. Information on sediment distribution and thickness is essential to the understanding of local and regional sediment transport, as well as the development of regional sediment-management plans. In addition, siting of any new offshore infrastructure (for example, pipelines, cables, or renewable-energy facilities) will depend on high-resolution mapping. Finally, this mapping will both stimulate and enable new scientific research and also raise public awareness of, and education about, coastal environments and issues.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title California State Waters Map Series-Offshore of Point Reyes, California
Series title Open-File Report
Series number 2015-1114
DOI 10.3133/ofr20151114
Year Published 2015
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Pacific Coastal and Marine Science Center
Description Pamphlet: iv, 39 p.; 10 Sheets: 52 x 36 inches or smaller ; Metadata; Data catalog
Country United States
State California
City Point Reyes
Projection Universal Transverse Mercator projection, Zone 10N
Scale 24000
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details