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California State Waters Map Series — Offshore of Santa Cruz, California

Open-File Report 2016-1024
By: , , , , , , , , , , , , , , , and 
Edited by: Guy R. Cochrane and Susan A. Cochran
https://doi.org/10.3133/ofr20161024

Links

  • Document: Pamphlet (pdf)
  • Sheets:
    • Sheet 1 (pdf) Colored Shaded-Relief Bathymetry, Offshore of Santa Cruz Map Area, California By Peter Dartnell, Andrew C. Ritchie, and David P. Finlayson
    • Sheet 2 (pdf) Shaded-Relief Bathymetry, Offshore of Santa Cruz Map Area, California By Peter Dartnell, Andrew C. Ritchie, and David P. Finlayson
    • Sheet 3 (pdf) Acoustic Backscatter, Offshore of Santa Cruz Map Area, California By Peter Dartnell, Andrew C. Ritchie, and David P. Finlayson
    • Sheet 4 (pdf) Data Integration and Visualization, Offshore of Santa Cruz Map Area, California By Peter Dartnell
    • Sheet 5 (pdf) Seafloor Character, Offshore of Santa Cruz Map Area, California By Mercedes D. Erdey and Guy R. Cochrane
    • Sheet 6 (pdf) Ground-Truth Studies, Offshore of Santa Cruz Map Area, California By Nadine E. Golden, Guy R. Cochrane, and Lisa M. Krigsman
    • Sheet 7 (pdf) Potential Marine Benthic Habitats, Offshore of Santa Cruz Map Area, California By Bryan E. Dieter, Charles A. Endris, H. Gary Greene, and Mercedes D. Erdey
    • Sheet 8 (pdf) Seismic-Reflection Profiles, Offshore of Santa Cruz Map Area, California by Samuel Y. Johnson, Stephen R. Hartwell, and Ray W. Sliter
    • Sheet 9 (pdf) Local (Offshore of Santa Cruz Map Area) and Regional (Offshore from Pigeon Point to Southern Monterey Bay) Shallow-Subsurface Geology and Structure, California By Samuel Y. Johnson, Stephen R. Hartwell, Janet T. Watt, Ray W. Sliter, and Katherine L. Maier
    • Sheet 10 (pdf) Offshore and Onshore Geology and Geomorphology, Offshore of Santa Cruz Map Area, California By Samuel Y. Johnson, Stephen R. Hartwell, and Clifton W. Davenport
  • Related Works:
  • Dataset: Data Catalog (html) The GIS data layers for this map are accessible from “Data Catalog—Offshore of Santa Cruz, California,” which is part of California State Waters Map Series Data Catalog. Each GIS data file is listed with a brief description, a small image, and links to the metadata files and the downloadable data files.
  • Data Release: USGS data release
  • Metadata: Metadata
  • NGMDB Index Page: National Geologic Map Database Index Page
  • Download citation as: RIS | Dublin Core

Introduction

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology.

The Offshore of Santa Cruz map area is located in central California, on the Pacific Coast about 98 km south of San Francisco. The city of Santa Cruz (population, about 63,000), the largest incorporated city in the map area and the county seat of Santa Cruz County, lies on uplifted marine terraces between the shoreline and the northwest-trending Santa Cruz Mountains, part of California’s Coast Ranges. All of California’s State Waters in the map area is part of the Monterey Bay National Marine Sanctuary.

The map area is cut by an offshore section of the San Gregorio Fault Zone, and it lies about 20 kilometers southwest of the San Andreas Fault Zone. Regional folding and uplift along the coast has been attributed to a westward bend in the San Andreas Fault Zone and to right-lateral movement along the San Gregorio Fault Zone. Most of the coastal zone is characterized by low, rocky cliffs and sparse, small pocket beaches backed by low, terraced hills. Point Santa Cruz, which forms the north edge of Monterey Bay, provides protection for the beaches in the easternmost part of the map area by sheltering them from the predominantly northwesterly waves.

The shelf in the map area is underlain by variable amounts (0 to 25 m) of upper Quaternary shelf, estuarine, and fluvial sediments deposited as sea level fluctuated in the late Pleistocene. The inner shelf is characterized by bedrock outcrops that have local thin sediment cover, the result of regional uplift, high wave energy, and limited sediment supply. The midshelf occupies part of an extensive, shore-parallel mud belt. The thickest sediment deposits, inferred to consist mainly of lowstand nearshore deposits, are found in the southeastern and northwestern parts of the map area.

Coastal sediment transport in the map area is characterized by northwest-to-southeast littoral transport of sediment that is derived mainly from ephemeral streams in the Santa Cruz Mountains and also from local coastal-bluff erosion. During the last approximately 300 years, as much as 18 million cubic yards (14 million cubic meters) of sand-sized sediment has been eroded from the area between Año Nuevo Island and Point Año Nuevo and transported south; this mass of eroded sand is now enriching beaches in the map area. Sediment transport is within the Santa Cruz littoral cell, which terminates in the submarine Monterey Canyon.

Benthic species observed in the Offshore of Santa Cruz map area are natives of the cold-temperate biogeographic zone that is called either the “Oregonian province” or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, the eastern limb of the North Pacific subtropical gyre that flows from southern British Columbia to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 300 km south of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off of central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment.

Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater, Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. The large extent of exposed inner shelf bedrock supports large forests of “bull kelp,” which is well adapted for high-wave-energy environments. The kelp beds are the northernmost known habitat for the population of southern sea otters. Common fish species found in the kelp beds and rocky reefs include lingcod and various species of rockfish and greenling.

Suggested Citation

Cochrane, G.R., Dartnell, P., Johnson, S.Y., Erdey, M.D., Golden, N.E., Greene, H.G., Dieter, B.E., Hartwell, S.R., Ritchie, A.C., Finlayson, D.P., Endris, C.A., Watt, J.T., Davenport, C.W., Sliter, R.W., Maier, K.L., and Krigsman, L.M. (G.R. Cochrane and S.A. Cochran, eds.), 2016, California State Waters Map Series — Offshore of Santa Cruz, California: U.S. Geological Survey Open-File Report 2016–1024, pamphlet 40 p., 10 sheets, scale 1:24,000, http://dx.doi.org/10.3133/ofr20161024.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Chapter 1. Introduction
  • Chapter 2. Bathymetry and Backscatter-Intensity Maps of the Offshore of Santa Cruz Map Area (Sheets 1, 2, and 3)
  • Chapter 3. Data Integration and Visualization for the Offshore of Santa Cruz Map Area (Sheet 4)
  • Chapter 4. Seafloor-Character Map of the Offshore of Santa Cruz Map Area (Sheet 5)
  • Chapter 5. Ground-Truth Studies for the Offshore of Santa Cruz Map Area (Sheet 6)
  • Chapter 6. Potential Marine Benthic Habitats of the Offshore of Santa Cruz Map Area (Sheet 7)
  • Chapter 7. Subsurface Geology and Structure of the Offshore of Santa Cruz Map Area and the Pigeon Point to Southern Monterey Bay Region (Sheets 8 and 9)
  • Chapter 8. Geologic and Geomorphic Map of the Offshore of Santa Cruz Map Area (Sheet 10)
Publication type Report
Publication Subtype USGS Numbered Series
Title California State Waters Map Series — Offshore of Santa Cruz, California
Series title Open-File Report
Series number 2016-1024
DOI 10.3133/ofr20161024
Year Published 2016
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Pacific Coastal and Marine Science Center
Description Pamphlet: iv, 40 p.; 10 Sheets: 60.0 x 36.0 inches or smaller; Data Catalog; Metadata
Country United States
State California
City Santa Cruz
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details