Geologic maps and structure sections of the southwestern Santa Clara Valley and southern Santa Cruz Mountains, Santa Clara and Santa Cruz Counties, California

The geology of this area was mapped by R. J. McLaughlin, J. C. Clark, E. E. Brabb, and E. J. Helley between 1988 and 1996; part of the Mt. Madonna quadrangle was mapped by C. J. Colon from 1991-1992. The geology of the New Almaden area is partly compiled from Bailey and Everhart, 1964. The geology along the San Andreas fault is partly incorporated from Sarna-Wojcicki and others, 1975 and from U. S. Geological Survey Staff, 1989.
Numerous scientists within the U.S. Geological Survey and from academia, have contributed to this database:
Critical paleontologic support was provided by: K. McDougall-Reid and Richard Pierce (deceased), Tertiary benthic foraminifers; D. Bukry, Tertiary nannofossils; J. Barron, Tertiary diatoms; C. Powell, W. Addicott, and J. Vedder, Tertiary macrofossils; W. V. Sliter (deceased), Mesozoic foraminifers; B. Murchey, Y. Isozaki, and I. Hattori, Mesozoic radiolaria; and W. Elder and D.L. Jones, Mesozoic macrofossils.
Isotopic data for age and provenance determinations were provided by R. Kistler and D. Champion, Rubidium and Strontium; J. Nakata, D. Sorg and P. Russell, K-Ar and Ar-Ar radiometric ages; and J. Wooden, U-Pb radiometric age.
A fission track age investigation, conducted in the map region in 1992-1994 by T. Dumitru, R. BŸrgmann, and Ramon Aerosmith, of Stanford University, in cooperation with the senior author, has contributed substantially to an understanding of the structural history of this area.
The senior author (McLaughlin) also wishes to acknowledge the following scientists for their collaborative and cooperative work, that has strongly influenced interpretations of the geology and crustal structure of the map region: R. Jachens, A. Griscom and V. Langenheim (U.S.G.S.), modeling of gravity and aeromagnetic data; R. BŸrgmann (Stanford, now at U.C. Berkeley), geodetic data; C.M. Wentworth and R.G. Stanley (U.S.G.S.), regional geology; R. Wells, D. Ponti, C. Prentice, D. Schwartz, S. Ellen, and K. Schmidt, (all at the U.S.G.S.), and W. Cotton ( W. Cotton and Associates), detailed work on surface deformation and active fault relationships following the 1989 Loma Prieta earthquake.
The authors wish to acknowledge the many owners of large land parcels and ranches in rural areas of Santa Clara and Santa Cruz Counties, who have cooperated with these mapping investigations by providing access to their properties and showing interest in the work. We also thank the following private and public agencies for their cooperation in allowing access and gate keys to their properties, including the San Jose Water Company; Mid- Peninsula Open-Space District; and the Santa Clara County Park system.
We also wish to thank the California Division of Forestry, particularly CDF Burrel Fire Station of Santa Cruz County, for providing lodging to the senior author (McLaughlin) in the course of mapping investigations.
This digital database was compiled in ARC/INFO, a commercial G.I. S.(ESRI). The digital compilation was done using the 1996 version 3.0 of the menu interface ALACARTE (originally published as version 1.0 by Fitzgibbon and Wentworth, 1991). The digitization of geologic contacts, development and integration of various data sets into the digital map database were largely supervised by C. M. Wentworth (1988-1997). Numerous individuals have compiled and edited parts of the digital files for this publication at different times, including T. A. Lindquist (1988), P. Showalter (1989-1990), C. E. Nelson (1994), L. Gerhardt ( 1996), C. R. Randolph, T. E. May, and J. L. Minnick (1996-1998), and Z. C. Valin (1996-2001). The digital geology was initially compiled as a part of the geologic map database for the San Jose, California 1:100,000-scale quadrangle (Wentworth and others, unpublished, 1999) but the maps are herein released at 1:24,000.
Geologic mapping was at a scale of 1:24,000, which is therefore the scale of maximum resolution. Enlargement of these maps to scales substantially less than 1:24,000 is here considered inappropriate.
Technical reviews of this report were provided by P. Stone ( Western Earth Surface Processes Team, U.S.G.S.) and by M. C. Blake, Jr., (Emeritus). R. Graymer (Western Earth Surface Processes Team, U.S.G.S.) reviewed the database. Technical editing of this report for publication by the U.S. Geological Survey was provided by J. Zigler, and preparation of the database website was by R. Koch and C. Donlin (all at Western Publications Unit, U.S.G.S.).
Note: Authorship of the geology of this publication resides in the first five names in the author list in the order given. The last nine names starting with Z.C. Valin, are the digital database authors in the order given.