Oregon Department of Geology and Mineral Industries has released highly detailed geological maps of Jackson and Josephine counties as part of the agency's Lidar Data Quadrangle. Lidar, a laser-mapping technology, allows for amazingly detailed and accurate mapping of the Earth's surface.
More detailed coverage information for the Rogue Valley area is provided in this index map PDF:
Lidar Data Quadrangle series publications are available on DVD and require specialty GIS software to view and use. LDQ series publications can be purchased directly via the web tool, http://www.oregongeology.org/sub/lidardataviewer/index.htm, or from the Nature of the Northwest Information Center, 800 NE Oregon St., Suite 177, Portland, OR 97232.
You may also call 503-872-2750 or order online at http://www.naturenw.org. There is a $4.95 shipping and handling charge for all mailed items.