Version history for Langenheim, V.E., Roberts, C.W., McCabe, C.A., McPhee, D.K., Tilden, J.E., and Jachens, R.C., 2006, Preliminary isostatic gravity map of the Sonoma Volcanic Field and vicinity, Sonoma and Napa Counties, California: U.S. Geological Survey Open- File Report 2006-1056 [available on the World Wide Web at URL http://pubs.usgs.gov/of/2006/1056/ ]. Version 1.0 July 31, 2008 Shapefiles created from the spreadsheet by J. Watson. March 6, 2006 Fixed a mistake in the data file of2006-1056_gravity.xls -- it doesn't affect the map and most people, but the terrain correction distance is different for the CDMG data than the others. February 28, 2006 Initial release online at http://pubs.usgs.gov/of/2006/1056/