EarthWorks Geospatial Catalog

Submarine Landslide Scarps: Hueneme Canyon and Vicinity, California, 2012

Author(s)
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Description
This line shapefile represents submarine landslide scarps of the geologic/geomorphic map of the Hueneme Canyon and surrounding vicinity in California. The offshore map area is characterized by two major physiographic features: (1) the nearshore continental shelf and upper slope; and (2) Hueneme Canyon and parts of three smaller, unnamed submarine canyons incised into the shelf southeast of Hueneme Canyon. The nearshore, shelf and slope are underlain by recent sediments and characterized by active sediment transport. Shelf and slope morphology and evolution result from drainage incision into deltaic sediments of the Oxnard plain during sea-level lowstand and subsequent sedimentation as sea level rose about 125 to 130 m over the last ~18,000 to 20,000 years (Lambeck and Chappell, 2001). Hueneme Canyon extends about 15 km offshore from its nearshore canyon head. The canyon is relatively deep (~150 m at the California's State Waters 3-nm limit) and steep (canyon walls as steep as 25 degrees to 30 degrees). The heads of the three smaller unnamed canyons southeast of Hueneme Canyon are not connected to the nearshore. During the last sea-level lowstand, these canyons were connected to coastal watersheds that fed coarse-grained sediment directly to Hueneme submarine fan (Normark and others, 2009). In the ensuing transgression, Hueneme Canyon maintained its connection with the shoreline as it eroded headward, while these smaller canyons were isolated and abandoned. "Outer" canyon walls in both Hueneme Canyon and the smaller unnamed canyons extend upward to the shelf edge and vary from smooth to deeply incised. "Inner" canyon walls occupy an intermediate position between the shelf edge and canyon floor. Both outer and inner canyon walls formed primarily by landsliding. Three different landslide units are mapped in Hueneme Canyon based on their morphology and relative age inferred from crosscutting and (or) draping relationships. Landslide units are undifferentiated where these morphology and relative age indicators are not distinct. The landslide units commonly include both steep erosional scarps and paired hummocky landslide deposits, and it is this genetic pairing (scarps with landslides) that distinguishes the scarps within landslide units from the scarps within the canyon-wall units. Lower-relief, sediment-draped, deep-seated slumps are mapped as separate landslide units. The map was published in Scientific Investigations Map 3225. This layer is part of the USGS Data Series 781.In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP) to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats and geology within the 3-nautical-mile limit of California's State Waters. CSMP has divided coastal California into 110 map blocks, each to be published individually as United States Geological Survey Open-File Reports (OFRs) or Scientific Investigations Maps (SIMs) at a scale of 1:24,000. Maps display seafloor morphology and character, identify potential marine benthic habitats and illustrate both the seafloor geology and shallow (to about 100 m) subsurface geology. Data layers for bathymetry, bathymetric contours, acoustic backscatter, seafloor character, potential benthic habitat and offshore geology were created for each map block, as well as regional-scale data layers for sediment thickness, depth to transition, transgressive contours, isopachs, predicted distributions of benthic macro-invertebrates and visual observations of benthic habitat from video cruises over the entire state. This coverage can be used to aid in assessments and mitigation of geologic hazards and to provide sufficient geologic information for land-use and land-management decisions both onshore and offshore.These data are intended for science researchers, students, policy makers, and the general public. This information is not intended for navigational purposes.The data can be used with geographic information systems (GIS) software to display geologic and oceanographic information. Additionally, this coverage can provide a geologic map for the public and geoscience community to aid in assessments and mitigation of geologic hazards in the coastal region and sufficient geologic information for land-use and land-management decisions both onshore and offshore. This information is not intended for navigational purposes.
Publisher
Geological Survey (U.S.)
Place(s)
California, Ventura County (Calif.), and Pacific Ocean
Subject(s)
Coasts, Geomorphology, Ocean bottom, Seismic reflection method, Geoscientific Information, and Oceans
Year
2012
Held by
Stanford
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Use and reproduction
This item is in the public domain. There are no restrictions on use.
Copyright
This work is in the Public Domain, meaning that it is not subject to copyright.
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