HM-01-18 1877 Geologic Map HM-01-18 1877 Geologic Map, Sheet XVIII: Geologic Cross Sections of the Western Slope and Central CO (Hayden)
HM-01-17 1877 Geologic Map HM-01-17 1877 Geologic Map, Sheet XVII: Geologic Cross Sections of the Front Range and Central CO (Hayden)