MI-16 1979 Geologic Map of Colorado (Tweto) Download Publication Details The definitive and now-classic state geologic map and explanation sheet for Colorado — “held as one of the finest examples of a state geologic map” — as compiled/mapped by Ogden Tweto. See MI-63 Geologic Sections Across Colorado (Tweto) for cross sections. The original paper map is unfortunately out of print but may occasionally be found on Ebay for those who miss the legacy format! 1 plate (1:500,000). Digital PDF download. MI-16D Citations Tweto, Ogden. “MI-16 Geologic Map of Colorado.” Geologic. Miscellaneous Investigations. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 1979. https://coloradogeologicalsurvey.org/publications/tweto-geologic-map-colorado-1979.