User specifically agrees not to misrepresent these data sets, nor to imply that changes they made were approved by the U.S. Geological Survey. Jack E. Harrison, Earle R. Cressman, James W. Whipple compiled the geology and published the original geologic paper map. Attribute accuracy was verified by manual comparison of the source with hard copy printouts and plots. Polygons intersecting the neatline are closed along the border. Segments making up the outer and inner boundaries of a polygon tie end to end to completely enclose the area.
Line segments are a set of sequentially numbered coordinate pairs.
No duplicate features exist nor do duplicate points in a data string. Intersecting lines are separated into individual line segments at the point of intersection. All nodes are represented by a single coordinate pair which indicates the beginning or end of a line segment. These two maps were the only maps used to create the digital geologic map database. The published paper geologic map was digitized by the EROS Data Center prior to 1994.