May 152017
 

Can you name the features of the endless Rocky Mountain skyline as seen from the Front Range? Where are they actually located? The OF-16-03 Colorado Rocky Mountain Front Profiles poster is the key to finding out. Similar profiles created in the past featured approximate or artistic interpretations of the many summits. This poster accurately locates the elevation points as they exist in geographic space.

The CGS is proud to present this unique perspective of the dramatic Front Range of Colorado as a large 54×28 in (137×71 cm) poster offset-printed on premium glossy stock. The author and designer of this special edition poster, Larry Scott, is a long-time member of the CGS staff. A talented illustrator, he handles the design work on our maps, books, pamphlets, posters, and other print material. This special project is the realization of his long-standing interest in Colorado topography.

The elevation profiles are drafted horizon lines of the heights of the Continental Divide eastward towards the High Plains. Each mesa, hogback, hill, mountain top, and points in between were plotted by intersecting its specific elevation with its latitude. The relative viewing elevation is about 9,500 ft (2900 m), the halfway point of the vertical scale. This allows one to see what cannot typically be seen from ground-level along the Front Range. If you’ve ever flown into/out of Denver International Airport — altitude 5430 ft (1655 m) — and are sitting on the west side of the plane, this is what you might see a few minutes after taking off or before landing. From this vantage, many of the great mountain ranges of central Colorado to come into view; the Sangre de Cristo, the Sawatch, the Mosquito, and others up to and occasionally beyond the Continental Divide.

Below the three profiles are 32 selected highlights of notable geographic, historic, and geologic locations as indicated via numbered circles. Many of these cite special locations for viewing the various peaks and summits. For example, on a clear day in Denver — something that happens around 300+ days a year — a perfect place to see the mountain horizon is from City Park on the west steps of the Museum of Nature and Science. At an elevation of 5,500 ft (1675 m), this panoramic vista includes much of the Front Range with the downtown Denver skyline in the foreground.

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From the Explanation:

Each profile is a one-degree section beginning in the south at 37° 42′, the central section at 38° 42’, and the northern section at 39° 42’. As the south-north extent of Colorado lies between 37° and 41° latitude, these profiles represent three-quarters of the Colorado Rocky Mountain Front Range. This refers the region of mountains that descend to the plains from the Pikes Peak massif in the south, north to the Wyoming border and inclusive of all summits east to the Continental Divide. South of Pikes Peak, the mountains begin to trend southwesterly all the way to Cañon City where the Arkansas River cuts through the Royal Gorge and flows out onto the piedmont. South of Cañon City, the Wet Mountains form a barrier that drops to the plains along Interstate-25 (I-25). Further south, though not shown, the mountains lay more to the west in a broad stretch, dramatically reappearing in the form of the Spanish Peaks, which extend eastward from the spine of the southernmost Sangre de Cristo Mountains in Colorado, the Culebra Range. To the north, beyond Rocky Mountain National Park, the mountains descend steadily to the Cache la Poudre River, marking the terminus of the Northern Section.

An excerpt:

Clear Creek Canyon — Long before there was an I-70 to access the high country there were only Native American foot trails along Clear Creek. In 1858, after trace amounts of gold were discovered in Cherry Creek south of Denver, gold seekers soon began looking in the mountains. Early in January 1859, George Jackson found gold at “Jacksons Bar”, where Chicago Creek joins Clear Creek in present-day Idaho Springs. The “gold rush” was on and the canyon became the gateway to the mining camps, most notably those in the Central City area via North Clear Creek. The Colorado Central Railroad (1871-1939) occupied the canyon in those days, later becoming the roadbed for US-6. The road was not completed in the canyon until 1952 due to political infighting and the time needed to complete six tunnels in the narrow spots. Rockfall remains a constant threat along the Canyon, with a notably large event closing the road in the summer of 2005 for almost three months—the longest full-road closure in state history.


Citation: Scott, Lawrence. OF-16-03 Colorado Rocky Mountain Front Profiles. Profile. Open File Report. Golden, CO: Colorado Geological Survey, May 2017.
May 032017
 

The CGS recently installed the first of five new seismic recording stations that will collect information on seismic events around the state and the region. The CGS seismic network acts in conjunction with those maintained by the University of Colorado and Colorado State University, the Incorporated Research Institutions for Seismology (IRIS), and the US Geological Survey‘s National Earthquake Information Center (NEIC) — to provide near real-time earthquake detection. The addition of our monitoring capacity, the wider network allows the geoscience research community to better understand background seismicity in Colorado and better discriminate between natural and induced seismic events that may occur in the region.

The CGS already operates four other stations with Streckeisen STS-2 Broadband Sensors (capable of sensing ground motions over the frequency band 0.01 Hz (100 sec) to 15 Hz). They were part of a national consortium — USARRAY — that was a portable seismic network migrating around to different locations in the US several years ago. State-level organizations were allowed to ‘adopt’ some of the stations that were deployed within each state. The CGS purchased the four stations in 2010 — they are included on the map below as red boxes.

The set-up for a typical recording station includes the seismometer and its associated data recorder, a power system, and a communications system. The install site is carefully chosen for its relative acoustic silence — such that human-caused (road and air-traffic) and natural (wind, animal) noise levels are minimal at the relevant frequencies. The CGS cooperates with the Colorado State Land Board and the Colorado State Parks system in locating optimal sites for the stations in the CGS network. The particular station illustrated here is our Briggsdale Seismic Station #T25A-1 near Greeley, Colorado. 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 »

Mar 142017
 

We just found out about this year’s Cumbres & Toltec Geology Train adventure in southwest Colorado/northwest New Mexico — 18 June 2017. It’s a special opportunity to enjoy some of that Rio Grande Rift, Brazos Uplift, Tusas Mountains, San Luis Basin, and San Juan Sag scenery.

Our very own Peter Barkmann, geologist extraordinaire and veteran Geology Train guide, will be on board for an informative and energized day in the high country.

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On June 18th, a special train will depart to traverse spectacular geology along the 64 miles of Cumbres & Toltec track. But simply experiencing the incredible overviews of the Rio Grande Rift, the eruptive evidence of the San Juan Volcanic field, the Precambrian core of the Tusas Mountains, recent glacial deposits, and snapshots of the Jurassic, will not be enough. This special train will stop at many outcrops and rail cuts along the right of way, to mingle, marvel and collect photographs, samples and experiences only accessible on the train route.

ALL ABOARD!

Feb 172017
 

The current annual Colorado Mineral and Energy Industry Activities report 2015-16 is now available. Following up on the 2014 report, this report, based on 2015 production data, sketches a comprehensive overview of Colorado’s mineral resource production. Of note is the fact that total value of mineral and energy fuels production in Colorado for 2015 is estimated to be $13.43 billion, a 29% decline from the $18.8 billion production value in 2014. The decline was caused primarily by a precipitous decrease in oil and gas market prices which provide 70% of Colorado mineral resource revenue. Oil and gas production actually registered at all-time highs of 127.6 Mbbl and 1,709 Bcf, respectively.

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Nonfuel mineral production — including metals, industrial minerals, and construction materials — posted a modest 3.9% increase in revenue. Increased production of crushed stone, cement, and sand and gravel aggregate accounted for the increase. With a 2015 production of 21,790 metric tons of molybdenum from two mines, Colorado is the largest molybdenum producer in the U.S. Although just one mine in the state publicly reported gold production in 2015, Colorado remains the third largest producer of the metal in the U.S. as it was in 2014.


Citation: Cappa, James A., Michael K. O’Keefe, James R. Guilinger, and Karen A. Berry. “IS-79 Colorado Mineral and Energy Industry Activities 2015-16.” Mineral and Energy Industry. Information Series. Golden, CO: Colorado Geological Survey, 2016.
Feb 062017
 

With all the precipitation in the Rockies this year (we’re at +153% normal snowpack at the moment), we thought we would re-release a publication that highlights at least one important aspect of Colorado snowfall — that is, the significant danger of avalanches. The Snowy Torrents: Avalanche Accidents in the United States 1980-86, compiled and written by Nick Logan and Dale Atkins and illustrated with Larry Scott’s fine pencil drawings, was first published in 1996. We still have a few hard-copies available and, because of that, yes, we do charge for the PDF download. However, Larry went back and re-made the PDF from the original publication file, producing a file that is far better than the rather poor digital scan we had offered previously.

The volume details 146 oft-times harrowing stories surrounding avalanches, the lives they claim, survivors and witnesses, along with assessments as to what happened, why it happened, and what could have been done to prevent loss of life and/or property. The authors are never judgmental, and their clear-eyed accounts contain a wealth of wisdom that will add to the knowledge-base of any winter backcountry enthusiast.

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Citation: Logan, Nick, and Dale Atkins. SP-39 The Snowy Torrents: Avalanche Accidents in the United States, 1980–86. Special Publications 39. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 1996.
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.
Jan 232017
 

The CGS’s Matt Morgan and Jon White were two of the co-authors on one of the top-ten Geological Society of America (GSA) 2016 book chapters and journal articles, this out of 600 papers. The article describes a comprehensive forensic analysis of the massive West Salt Creek rock avalanche that occurred in late May 2014 in western Colorado (USA). The analysis relied on large-scale (1:1000) structural mapping accomplished via high-resolution unmanned aircraft system imagery along with seismic data generated by more than twenty stations within approximately 500 miles (800 km) of the event. The avalanche was the largest mass-movement slope failure in the historical record of Colorado: it killed three people and narrowly avoided destroying a gas wellhead.

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Citation: Coe, Jeffrey A., Rex L. Baum, Kate E. Allstadt, Bernard F. Kochevar, Robert G. Schmitt, Matthew L. Morgan, Jonathan L. White, Benjamin T. Stratton, Timothy A. Hayashi, and Jason W. Kean. 2016. “Rock-Avalanche Dynamics Revealed by Large-Scale Field Mapping and Seismic Signals at a Highly Mobile Avalanche in the West Salt Creek Valley, Western Colorado.” Geosphere 12 (2): 607–31. doi:10.1130/GES01265.1.