Lithology and aggregate quality attributes for the digital geologic map of Colorado

This geologic map was prepared as a part of a study of digital
methods and techniques as applied to complex geologic maps. The
geologic map was digitized from the original scribe sheets used to
prepare the published Geologic Map of Colorado (Tweto 1979).
Consequently the digital version is at 1:500,000 scale using the
Lambert Conformal Conic map projection parameters of the state base
map. Stable base contact prints of the scribe sheets were scanned on
a Tektronix 4991 digital scanner. The scanner automatically converts
the scanned image to an ASCII vector format. These vectors were
transferred to a VAX minicomputer, where they were then loaded into
ARC/INFO. Each vector and polygon was given attributes derived from
the original 1979 geologic map.