This layer is a georeferenced raster image containing the slope map of Hueneme Canyon and the surrounding vicinity in California. A smoothed slope was used as an interpretation aid for mapping geomorphology of Hueneme Canyon. The slope raster, in conjunction with bathymetry data, amplitude data, and seismic reflection profiles, was used to interpret geology and geomorphology of Hueneme Canyon. The slope raster was generated in two steps. First, the source elevation data were combined into a single elevation raster and smoothed using a FocalMean algorithm in ArcGIS 9.3.1, as follows: focalmean([elevation_source], circle, 4, data) This operation smoothes the data by calculating the mean of all cells for which the cell center is within a 4-cell radius of the target cell - essentially calculating a rolling mean of elevation over the entire grid. Second, the slope, in degrees, of the smoothed source elevation data was calculated using the 3D-analyst slope function in ArcGIS 9.3.1. This function calculates the maximum rate of change in a plane fitted through a 3x3 neighborhood around the target cell. The rate of change is calculated using the average maximum technique of Burrough and McDonell (1998). 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 as an interpretive aid for geologic mapping purposes. 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. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.