As a detailed follow-up to the earlier MS-53 Colorado Stratigraphic Chart, a new collaboration between the CGS and the Denver Museum of Nature and Science (DMNS) generated this stratigraphic chart for the state of Colorado focusing on the Cretaceous period. The chart was designed from the ground up to illustrate Cretaceous stratigraphy spanning the state’s many sedimentary basins. It builds upon the work of dozens of colleagues and updates Richard Pearl’s seminal 1974 stratigraphy chart. The chart leverages the community’s stratigraphic work in both the subsurface and outcrop, and depicts new geochronologic constraints for many units. To facilitate comparison of strata to external forcing factors, the chart employs a linear timescale. Each unit’s dominant depositional environment is depicted as are major mountain building events, erosional events, and regional unconformities. This high-resolution PDF file may easily be printed up to its original size ~42×30-inches. Digital PDF download. MS-54D
From the chart itself:
Colorado’s stratigraphy is dominated by gaps. The distribution of strata reflects the tectonic and climatic evolution of each of the region’s eleven basin areas. To foster comparison of these patterns, we have organized the stratigraphy using a linear timescale and illustrated where orogenic uplift has led to removal of strata or nondeposition. Not all orogenic features are illustrated on the chart. For example, some orogenies caused sediment ponding and accumulation in intermontane basins, such as during the Laramide in northwestern Colorado. In the past ~10 Ma, regional uplift has raised Colorado and has allowed the modern landscapes to be created due to erosion. The chart’s color scheme for stratigraphic units gives a sense of dominant lithologies and depositional environments across basins. Updates to this chart, as well as additional stratigraphic resources, such as stratigraphic and structural cross-sections, may be found at https://coloradostratigraphy.org. To learn more about the unit names on this chart, resources are available at the U.S. Geological Survey’s Geolex site. This data has been re-cast against the International Commission on Stratigraphy’s chronostratigraphic chart v. 2015/01, updated at https://stratigraphy.org.