| Abstract: | This data set maps and describes the geology of the Fifteenmile Valley 7.5‘ quadrangle,
San Bernardino County, California. Created using Environmental Systems Research
Institute‘s ARC/INFO software, the data base consists of the following items: (1) a map
coverage containing geologic contacts and units, (2) attribute tables for geologic units
(polygons), contacts (arcs), and site-specific data (points). In addition, the data set
includes the following graphic and text products: (1) A PostScript graphic plot-file
containing the geologic map, topography, cultural data, a Correlation of Map Units (CMU)
diagram, a Description of Map Units (DMU), an index map, a regional geologic and structure
map, and a key for point and line symbols; (2) PDF files of this Readme (including the
metadata file as an appendix), Description of Map Units (DMU), and a screen graphic of the
plot produced by the PostScript plot file.
The geologic map covers the northernmost part of the San Bernardino Mountains and the
southern Granite Mountains. These two bedrock areas are separated by the wide, alluviated
Fifteenmile Valley. Bedrock units in the San Bernardino Mountains are dominated by large
Cretaceous granitic bodies ranging in composition from monzogranite to gabbro, and include
lesser Triassic monzonite. The Granite Mountains are underlain chiefly by large Triassic
monzonite bodies, and in the western part, by Cretaceous and possibly Jurassic
monzogranite to monzodiorite. Spanning the Pleistocene in age, large alluvial fans, flank
the north side of the San Bernardino Mountains, and are dominated by debris flow deposits.
The central part of Fifteenmile Valley is covered by fine grained alluvial material
deposited by streams flowing into Rabbit Lake and an unnamed dry lake in the northwestern
part of the quadrangle. Young, south dipping reverse faults, some with moderately to well
eroded fault scarps, discontinuously flank the northern edge of the San Bernardino
Mountains. Young and old high-angle faults are mapped within both the San Bernardino and
Granite Mountains.
The geologic map database contains original U.S. Geological Survey data generated by
detailed field observation and by interpretation of aerial photographs. The map was
compiled on a base-stable cronoflex copy of the Fifteenmile Valley 7.5‘ topographic base
and then scribed. This scribe guide was used to make a 0.007 mil blackline clear-film,
which was scanned at 1200 DPI by Optronics Specialty Company, Northridge, California;
minor hand-digitized additions were made at the USGS. Lines, points, and polygons were
subsequently edited at the USGS using standard ARC/INFO commands. Digitizing and editing
artifacts significant enough to display at a scale of 1:24,000 were corrected. Within the
database, geologic contacts are represented as lines (arcs), geologic units as polygons,
and site-specific data as points. Polygon, arc, and point attribute tables (.pat, .aat,
and .pat, respectively) uniquely identify each geologic datum. |
| Genre: | USGS Numbered Series |
| ProdID: | 31368 |
| Citation Author: | Miller, F. K.; Matti, J. C. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | 24 p., 1 over-size sheet, scale 1:24,000 (1 inch = 2,000 feet). |
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| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 2001-132 |
| Citation Search Results Text: | Geologic map of the Fifteenmile Valley 7.5‘ quadrangle, San Bernardino County, California; 2001; OFR; 2001-132; Miller, F. K.; Matti, J. C. |
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| Citation Year: | 2001 |
| Type: | citation/reference |
| Text: | Geologic map of the Fifteenmile Valley 7.5‘ quadrangle, San Bernardino County, California; 2001; OFR; 2001-132; Miller, F. K.; Matti, J. C. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/usgs_thumb.jpg |
| URL (INDEX PAGE): | http://geopubs.wr.usgs.gov/open-file/of01-132/ |
| Date Other: | Tue, 1 Jan 2002 00:00 -0600 |
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