Preliminary digital terrain map of mélange and intact rock determined by interpretation of terrain details in the junction area of Coastal and Central belts of the Franciscan Complex between Gualala and Ukiah, northern California Coast Ranges
A terrain-based map at a resolution of 1:100,000 of a large area of Franciscan Complex between the San Andreas and Maacamas faults east of Point Arena, California, delineates varied areas of erosionally resistant topography and contrasting subdued topography, including an area of interspersed patches of each that form a pattern unlike prior, mostly reconnaissance geologic mapping.
These two terrain types are distinguished using differences in the detailed shapes of individual topographic elements that in these rocks are indicative of relatively intact rock or mélange. Most of the line work in the map is based on interpretation of small-scale aerial photographs (< about 1:50,000) or of slope and curvature maps prepared from a 10-meter elevation grid. Geologic identification of most of the resultant polygons is variously obtained from existing geologic maps, the topographic character determined while mapping the lines, or spatial association with identified polygons, although some in the central part of the map remain identified only by topographic character.
This data release contains two shape files, one containing lines and one polygons, together with a metadata file that describes those files. Database fields in the line file describe type of line (Ltype), the confidence in the existence of geologic lines and their accuracy of location (Quality), how they are mapped (Source), and for some lines their identity also as source-area boundaries or named major faults (Bndry). Fields in the polygon file describe identity (Ptype), how those identities were determined (Source), and terrain hardness (Hardness) as resistant (Hard; Hd), subdued (Soft: SF), or Intermediate (In) in various combinations and relative abundance.
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Complete Metadata
| @type | dcat:Dataset |
|---|---|
| accessLevel | public |
| bureauCode |
[ "010:12" ] |
| contactPoint |
{ "fn": "Carl M Wentworth", "@type": "vcard:Contact", "hasEmail": "mailto:cwent@usgs.gov" } |
| description | A terrain-based map at a resolution of 1:100,000 of a large area of Franciscan Complex between the San Andreas and Maacamas faults east of Point Arena, California, delineates varied areas of erosionally resistant topography and contrasting subdued topography, including an area of interspersed patches of each that form a pattern unlike prior, mostly reconnaissance geologic mapping. These two terrain types are distinguished using differences in the detailed shapes of individual topographic elements that in these rocks are indicative of relatively intact rock or mélange. Most of the line work in the map is based on interpretation of small-scale aerial photographs (< about 1:50,000) or of slope and curvature maps prepared from a 10-meter elevation grid. Geologic identification of most of the resultant polygons is variously obtained from existing geologic maps, the topographic character determined while mapping the lines, or spatial association with identified polygons, although some in the central part of the map remain identified only by topographic character. This data release contains two shape files, one containing lines and one polygons, together with a metadata file that describes those files. Database fields in the line file describe type of line (Ltype), the confidence in the existence of geologic lines and their accuracy of location (Quality), how they are mapped (Source), and for some lines their identity also as source-area boundaries or named major faults (Bndry). Fields in the polygon file describe identity (Ptype), how those identities were determined (Source), and terrain hardness (Hardness) as resistant (Hard; Hd), subdued (Soft: SF), or Intermediate (In) in various combinations and relative abundance. |
| distribution |
[ { "@type": "dcat:Distribution", "title": "Digital Data", "format": "XML", "accessURL": "https://doi.org/10.5066/P1HRMWDE", "mediaType": "application/http", "description": "Landing page for access to the data" }, { "@type": "dcat:Distribution", "title": "Original Metadata", "format": "XML", "mediaType": "text/xml", "description": "The metadata original format", "downloadURL": "https://data.usgs.gov/datacatalog/metadata/USGS.68da9f8bd4be021b36eb5f73.xml" } ] |
| identifier | http://datainventory.doi.gov/id/dataset/USGS_68da9f8bd4be021b36eb5f73 |
| keyword |
[ "Boonville", "Boonville fault", "California", "Cedars fault", "Franciscan Complex", "GIS", "Gualala", "Mélange", "Point Arena", "USGS:68da9f8bd4be021b36eb5f73", "Ukiah", "Yorkville", "biota", "digital map database", "terrain", "topography" ] |
| modified | 2025-12-16T00:00:00Z |
| publisher |
{ "name": "U.S. Geological Survey", "@type": "org:Organization" } |
| spatial | -123.7500, 38.6250, -123.1250, 39.2500 |
| theme |
[ "geospatial" ] |
| title | Preliminary digital terrain map of mélange and intact rock determined by interpretation of terrain details in the junction area of Coastal and Central belts of the Franciscan Complex between Gualala and Ukiah, northern California Coast Ranges |
