Nov 152017
 
Water Resources Investigation WRI 2017-1a, The Upper Pierre Aquifer of the Cheyenne Basin, Northeastern Colorado, Geologic Cross Sections

Our friends over at the Colorado Division of Water Resources (CDWR) have just released Water Resources Investigation WRI 2017-1a, The Upper Pierre Aquifer of the Cheyenne Basin, Northeastern Colorado, Geologic Cross Sections, authored by Ralf Topper, Clinton D. Meyer, Marshall Haworth, Kevin C. Donegan, Hillary Banks, Aaron Bandler, Andrew Flor, and Matthew A. Sares.

Summary:

This report is a compilation of ten regional geologic cross sections created from interpretation of geophysical logs from 200 oil and gas wells. It is the first of a two-part hydrogeologic study of the Upper Pierre aquifer within the Cheyenne Basin of northeastern Colorado and consists of a short text report along with 11 plates. The cross sections depict the following geologic/hydrogeologic intervals: South Platte River alluvial aquifer, Ogallala Formation, White River Formation, Laramie Formation, Fox Hills Sandstone, Upper Pierre Shale upper confining layer, Upper Pierre aquifer, Pierre Ash, and the Upper Pierre Shale lower confining layer.

The text, maps, and cross sections may be downloaded from the DWR Homepage in the “New!” section in the middle of the page.

Contact Matthew A. Sares, Manager, Hydrogeological Services with any questions.

Jun 272017
 
OF-16-02 Geologic Map of the Watkins Quadrangle, Arapahoe and Adams Counties, Colorado

We’ve just uploaded the next of our free STATEMAP quadrangle map products to our online store: the Geologic Map of the Watkins Quadrangle, Arapahoe and Adams Counties, Colorado. The STATEMAP series in general provides a detailed description of the geology, mineral and ground-water resource potential, and the geologic hazards of an area. This free release from the CGS includes two plates (with a geologic map, cross-section with correlation, oblique 3D view, legend, and description) along with the corresponding GIS data package that allows for digital viewing, all in a single zip file.

Location of the Watkins Quadrangle, Arapahoe and Adams Counties, Colorado.

Location of the Watkins Quadrangle, Arapahoe and Adams Counties, Colorado.

Matt Morgan, Senior Research Geologist and CGS Deputy Director, along with Senior Engineering Geologist (Emeritus) Jon White generated this map with special input from Richard Madole (surficial geology) and Shannon Mahan (OSL analysis), both of the USGS. This free release from the CGS includes two PDF plates (with a geologic map, cross-section with correlation, oblique 3D view, and legend) along with the corresponding GIS data package that allows for digital viewing, all in a single ZIP file. Continue reading »

Apr 122017
 
OF-16-05 Geologic Map of the Longmont Quadrangle, Boulder and Weld Counties, Colorado

We just uploaded the most recent of our STATEMAP mapping products to our online store: the Geologic Map of the Longmont Quadrangle, Boulder and Weld Counties, Colorado. The STATEMAP series in general provides a detailed description of the geology, mineral and ground-water resource potential, and the geologic hazards of an area. This particular 7.5-minute, 1:24,000 quadrangle is located immediately east of the Front Range uplift of Colorado and includes most of the town of Longmont within its borders. The geologic map plates were created via traditional field mapping, structural measurements, photographs, and field notes acquired by the investigators. Richard F. Madole, Scientist Emeritus at the USGS was the lead geologist for the project. This free release from the CGS includes two plates (with a geologic map, cross-section with correlation, oblique 3D view, legend, and description) along with the corresponding GIS data package that allows for digital viewing, all in a single zip file.

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From the map history: Continue reading »

Jan 312017
 

A collaboration between the CGS and the Denver Museum of Nature & Science (DMNS) has resulted in a new stratigraphic chart for the state of Colorado. This beautifully (offset-)printed 42″ x 39″ color chart was designed from the ground up to illustrate the Proterozoic to Holocene stratigraphy that spans the state’s many sedimentary basins. A collaborative effort led by Robert Raynolds and James Hagadorn, the chart 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. Printed on heavy-duty 100# coated cover stock, these rolled posters may be purchased from the CGS online bookstore. They will make a fine gift for geoscientists, rockhounds, or anyone interested in how Colorado’s magnificent landscapes came to be.

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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, depicted in the map below. 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 http://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 chart scaffolds on the work of Richard H. Pearl’s 1977 compilation (Rocky Mountain Association of Geologists, Special Publication 2). With the exception of the Carboniferous and Permian periods, this data has been re-cast against the International Commission on Stratigraphy’s chronostratigraphic chart v. 2015/01, updated at http://stratigraphy.org.


Citation: Raynolds, R. G., and James W. Hagadorn. “MS-53 Colorado Stratigraphy Chart.” Stratigraphic. Map Series 53. Denver, CO: Colorado Geological Survey and the Denver Museum of Nature & Science, January 2017.