Geology of the onshore part of San Mateo County, California: A digital database

Base Map layers were prepared from scale-stable printing negatives of the U.S. Geological Survey Palo Alto (1982 edition) and San Francisco (1978 edition) 1:100,000 topographic map, which has a 50 meter contour interval. Scanned and vectorized images were transformed from scanner coordinates to projection coordinates with digital tics placed by hand at map corners. The images were then trimmed interactively by hand using ALACARTE to conform to the area of the geologic coverages. Small mismatches at the boundaries caused by slight differences in the original scans remain in the three base map coverages. These base map layers are digital images but no information other than location is attached to the lines. The base maps are provided for reference only.

The geologic map information was digitized from stable originals of the geologic maps at 1:24,000 and 1:62,500 scale. The author manuscripts (pencil on mylar) were scanned using a Altek monochrome scanner with a resolution of 800 dots per inch. The scanned images were vectorized and transformed from scanner coordinates to projection coordinates with digital tics placed by hand at quadrangle corners. The scanned lines were edited interactively by hand using ALACARTE, color boundaries were tagged as appropriate, and scanning artifacts visible at 1:24,000 were removed.
The source map (see lines in coverage sm_so) subdivides the mapped region into 20 numbered sections. The authors of OFR 98-137 relied on a variety of published and unpublished sources of information to compile the map. The references and comments listed here indicate which sources of information were used by the authors to map each section.
1. Bonilla (1965). See also Hall (1965a and b).
2. Darrow (1963), modified from Pampeyan (1994), and field checking by authors.
3. Lawson (1914), extensively modified from Pampeyan (1994), and field checking by authors.
4. Jack (1969). See also Glen (1959) and Pampeyan (1994).
5. McLauglin (1969); some field checking by E.E. Brabb, 1969, and E.H. Pampeyan, 1971.
6. Pampeyan (1970b and 1993)
7. Unpublished geologic mapping by S.A. Brooks, K.F. Oles, and Eugene Borax, Union Oil Company of California, 1956, scale 1:24,000; some data from Classen (1959). Additional field work by T.W. Dibblee, Jr. 1947-49, and by E.E. Brabb, 1968-69.
8. New mapping by authors.
9. Thomas (1951) and field reconnaissance by E.E. Brabb, 1969, and E.H. Pampeyan, 1963.
10. Schlocker and other (1965), and Brown (1972).
11. Esser (1958), and Mack (1959), modified by field checking by E.E. Brabb, 1968-69.
12. Pampeyan (1970a and 1993). Some data from Dibblee ( 1966).
13. Helley and Graymer (1997).
14. Touring (1959). See also Cummings and others (1962). Bedrock geology modified from unpublished maps, scale 1:24,000, by F.J. Noble, S.A. Brooks, Eugene Borax, K.F. Oles, R. S. Fiske, H.L. Fothergill, R.N. Hacker, and J.H. van Amringe, Union Oil Company of California, 1951-57. Additional field work by T.W. Dibblee, Jr., 1947-49 and E.E. Brabb, 1958, 1968-69.
15. Dibblee (1966) and Johnson and Ellen (1968).
16. Dibblee (1966). Some data from Cummings (1960) and Cummings and others (1962).
17. Unpublished geologic mapping, scale 1:24,000 by S.A. Brooks and R.S. Fiske, Union Oil Company of California, 1956. Additional field work by T.W. Dibblee, Jr., 1947-49, J.C. Clark and E.E. Brabb, 1969-70, and T.R. Simoni, 1971. Some San Gregorio fault lines from Weber and Lajoie (1980) and Roberta Smith (written communication, 1993). See also Hall and others (1959).
18. Brabb (1960). See also Cummings and others (1962) and Brabb (1964).
19. Cummings (1960). See also Cummings and others (1962).
20. Clark (1970), Clark and Brabb (1978), and Brabb, Clark, and Throckmorton (1977). More recently Clark (1981).