If the user has modified the data in any way they are obligated to describe the types of modifications they have performed on the hardcopy map. User specifically agrees not to misrepresent these data sets, nor to imply that changes they made were approved by the U.S. Geological Survey. G. Stephen Pitts assisted with the design of the data model, entered the explanatory and source text, assisted in creating the look-up tables, and wrote the metadata. Accuracy of the Attribution was verified by manual comparison of the sources with hard copy printouts and plots. Polygons intersecting the neatline are closed along the border.
Line segments are a set of sequentially numbered coordinate pairs.
No duplicate features exist nor 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. The map boundary came from the scan, was projected to Lambert Conformal Conic. From subsequent mapping, errors are known to exist with the structure and geochronology.