McCalpin, J.P., 1996, General geology of the northern San Luis Valley, Colorado, in Thompson, R.A., Hudson, M.R. and Pillmore, C.L. (eds.), Geologic Excursions to the Rocky Mountains and Beyond: Field Trip Guide for the 1996 Annual Meeting, Geological Society of America, Denver, CO, Oct. 28-31, Field Trip 20, Section II, Geology and Hydrogeology; CD-ROM, Special Publication 44, Colorado Geological Survey, Denver, CO, 11 p.