1. Geologic Map of the O'Neill 1º X 2º Qwaudrangle, Nebraska with configuration maps of surfaces of formations\ Maps University Of Nebraska Lincoln Public content 1990. Diffendal, Jr., Robert. SCALE 1:250,000 CONTOUR INTERVAL 200 FEET Geology mapped principally from 1991-2000 by RFD, M.RV, E.JV, H. LG , and C.LT Editing and layout by R.F....