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)
HM-01-15 1877 Geologic Map HM-01-15 1877 Geologic Map, Sheet XV: SW CO and parts of NM, AZ and UT (Hayden)
HM-01-16 1877 Geologic Map HM-01-16 1877 Geologic Map, Sheet XVI: South-Central CO and Part of NM (Hayden)