The data supplied in this publication are made available with geographic coordinates to allow the data to be incorporated into a Geographic Information System (GIS). The data layers along with additional base-map layers have been compiled into an ESRI™ ArcView® project file (usSEABED_Pacific.apr) (zip file, 32 MB), which is located within the Data directory of this publication. The project file serves to provide examples of how the data can be displayed in a GIS. It contains several views demonstrating the possibilities of the various data files. A variety of base map layers that can be used to accompany these data can be found on the Coastal and Marine Geology Program's U.S. Pacific Pacific Coast Map Server. Several have been included below and are used in the project file. Other examples of ways to visualize these data are also included.
For those who do not have the ESRI™ software or a compatible GIS data browser available on their computer, a free viewer, ArcExplorer®, is available from ESRI. Please note that the ArcExplorer® software is limited to the Microsoft Windows operating systems.
Clicking on the layer name under the column header "Data Layer Name & Description" in the table below will open a new window with a graphical representation of that layer. Federal Geographic Data Committee (FGDC) metadata are included with data layers in four formats in the table below: (HTML, FAQ, XML, and text).
A downloadable zip archive file containing the elements that comprise the ArcView® shapefile for each data layer is also provided. In addition to the ArcView shapefile, the usSEABED data layers are available in an ASCII text format as an alternate way to view and examine the data sets. The first record of the ASCII file contains the name of the data fields for that file. Each zip file includes:
- ArcView® shapefile for each layer (with associated files)
- Comma-delimited text version of the data file
- Metadata to accompany data file (four versions)
- Browse graphic of the data layer
- A README file
The zip files were created using WinZip 9.0. Users may obtain a free version of the software from www.winzip.com.
PAC_SRC — A comma-delimited text file containing a list of sources included in the output files. The "DataSetKey" number within this file gives a relational link between the source data set and the data files listed below.
Also provided are lists (Data Sources and by DataSetKey) of all sources of data with links to associated HTML metadata and browse graphics.
usSEABED Pacific (California, Oregon, Washington) Data:
To map the coded information on Color and Roughness in a GIS, load the ArcView® legends "munsell.avl" or "rgh_pt.avl" which are available with the database. ArcView® legends may be imported into ArcGIS®. To make your own legends for other applications, employ a classification that uses a "unique value" process.
Color of sediment is described either in terms (brown, light greenish gray) or in Munsell color codes given in values of hue (spectral content), value (lightness), and chroma (saturation). Munsell codes are explained in a publication of the Geological Society of America (Goddard, and others, 1951).The dbSEABED program converts the former into average values of Munsell codes, rounded to increments of 5 in hue, 3 in value, and 3 in chroma (Jenkins, 2003). An ESRI™ ArcView® legend is included for ease of mapping.
This is a coded output representing the V:H of the seabed roughness element which is observed with greatest aspect ratio. That feature may be fixed roughness like a cobble, or moveable roughness like ripples. The outputs can only report observed roughness elements, so are influenced by the size scales of samplers and observations.
The V and H values are the centimeter values of the height and horizontal dimensions written in integer log 2 (base 2). For example "4:6" represents 16 cm height over length scale of 64 cm. Powers <0 are set to zero (i.e., scales <1 cm are not considered). The horizontal length H is the length of expression of a feature, rather than wavelength of repetition. Where a feature is elongated, H is taken normal to elongation (i.e., equals ripple wavelength).
Roughness: AVL | JPG