Welcome from the State Geologist of Colorado

Title: Welcome from the State Geologist of Colorado

Author: Vince Mathews

Publication: The Outcrop, June 2009, p. 6-10, 14

INTRODUCTION

Colorado has some of the most diverse, well-displayed geology anywhere in the world. From rocks billions of years old to sand dunes shifting today, the state has an incredible array of geologic features of all types. Geologists have marveled at Colorados spectacular geology for more than a century. Dr. F. V. Hayden wrote in 1869, “I do not know of any portion of the West where there is so much variety displayed in the geology as within a space of ten miles square around Colorado City (today’s Colorado Springs). Nearly all the elements of geological study revealed in the Rocky Mountains are shown on a unique scale in this locality.I hope that you will spend some time getting out and experiencing our fantastic geology firsthand.

Do you think Denver’s mile-high elevation is impressive? Colorado ‘s average elevation is more than a quarter of a mile higher. Want to stretch your legs? We have 58 named peaks over 14,000′ in elevation. To get from the lowest point where the Arikaree River enters Kansas to the highest point in the Sawatch Range requires an elevation gain of 2.11 vertical miles.

Our State Geologist, Vince Mathews, welcomes you to Colorado.

Interested in starting a frontier gas play in Precambrian rocks?  We have the largest exposure of Precambrian rocks in the lower 48. Indeed, we have more granitic rocks than the “Granite State.” The Pikes Peak batholith alone covers 1,300 square miles. If you are interested in metamorphic rocks, you can start at the mouth of Big Thompson Canyon in biotite­, garnet,  staurolite, kyanite, and sillimanite zones. In the sillimanite zone you begin to see migmatites and  pegmatite  offshoots  from the 600-squaremile batholith around Estes Park. Eventually you reach the batholith and Rocky Mountain National Park (RMNP). Interested in glacial features? You can drive eight miles from a terminal moraine at the RMNP Entrance Station right up into the cirque.Along the way, you will pass between prominent lateral moraines and into the u-shaped valley that is grooved and  polished on  its walls and floors.  Bored by these remnants of past glaciations and hunger for the real thing? Hike up to Andrews Glacier. Or, hike up to one of the many spectacular rock glaciers in RMNP. Have you seen or visited only the Front Range?  If so, you have just scratched the surface of the scenery and underlying geology of Colorado. The San Juan Mountains of southwestern Colorado look nothing like the Front Range. Their colorful, rugged strata derived from a complex of calderas, volcanic strata, metamorphic and intrusive Rocks and sedimentary strata; giving them the nickname of “Switzerland of America.”

Looking to the north from the San Juans you can see Grand Mesa’s 11,000- foot-high, basalt-capped plateau on the horizon. These flows are only part of the extensive  Late Tertiary and Quaternary basaltic volcanism associated with  Rip Grande Rifting. From Grand Mesa you can look down on the impressive monoclines of Colorado National Monument, or the intriguing  stratigraphy of the Book Cliffs. On the way from Grand Mesa to Denver, you will drive over a 4,150-year-old basalt flow.

The horst in Leadville Limestone along Highway 550 north of Durango has iron-stained tufa mounds where mineral-rich waters from below used the faults to migrate to the surface. UTM 251832E 4148850N. Photo by Vince Mathews, CGS.

Want to study eolian strata and processes? You can visit huge stacks of late- Paleozoic eolian strata in Dinosaur National Monument or Mesozoic eolian strata in Colorado National Monument. Or, you may want to wander through the Permian dunes of the famous Lyons quarries. Don’t like dunes that old? Try the Pleistocene dunes on the eastern High Plains in the 5,000-square-mile, Wray dune field. If you want to understand those features you observed in the old dunes, visit the Great Sand Dunes National Park and Preserve (GSDNPP) where the tallest dune in North America resides (20 stories higher than the tallest building in downtown Denver). In this modern dune field you can slog up slip faces and get blasted with migrating volcanic sand grains. A sharp eye can spot star dunes, lunette dunes, transverse dunes, barchan dunes, coppicee dunes, parabolic dunes, and reversing dunes. And,  while you are at the GSDNPP you can stroll over to the Holocene fault scarp on the bounding fault of the Sangre de Cristo Range that has experienced 20,000+ feet of displacement during the Neogene.The Sangre de Cristo fault is shown on the National Earthquake Hazard Map as being  capable  of  generating a  magnitude  7.5  earthquake. Maybe you will get lucky while you are examining the fault!

And, don’t forget to visit the rest of our wonderful geologic hazards. The world-famous four-mile long Slumgullion landslide is worth the drive, Just southwest of Denver is the zip code with the largest dollar loss from swelling soil in the nation. Drive up I-70 to Georgetown and Silver Plume to see debris flows, avalanche chutes, and rockfalls.

Need energy? Colorado is a major producer in all sectors: uranium coal, oil, natural gas, wind, and solar. Uranium mining began more than a century ago. Over 20,000 mining claims were filed on federal land in the state in just the past three years. We have all or parts of seven of the 52 largest natural gas fields (including three of the top ten) in the United States. Natural gas production has set a new record for each of the past 25 years making us the sixth largest producer of natural gas in the nation. We have the fifth largest gas reserves and the largest reserves of coal bed methane in the nation. In oil we have the 16th and 65th largest oil fields in the United States. We have the largest reserves of compliance coal in the nation. As a consequence we send our low sulfur, low mercury, and low ash coal to 27 other states. Our productivity per miner is 33% higher than the national average. And, we do it safely. We are fourth in the nation for wind energy and have the 16th largest solar PV facility in the world.

Into structural  geology? We have it all. Like folds? Try our  homoclines, monoclines, anticlines , sync lines, domes,  basins, salt cored folds , basement cored folds, refolded folds, syndepositional folds, evaporite­ flowage folds, disharmonic folds, and forced folds. Prefer faults? We have thrust faults, reverse faults, normal faults, grabens, and a horst? And what a horst! Iron-stained tufa mounds were deposited on top of each bounding fault as mineral-rich waters found pathways up the faults. Maybe you just like fossils. You came to the right place! This is the home of dinosaurs, the first discovery of a T-Rex fossil and first Triceratops. Indeed, South Table Mountain in Golden was the first place in the  world where it was recognized back in the 1940s that the K/T contact had abundant dinosaur fossils in the Cretaceous strata below and only mammals in the overlying Tertiary layers. You can see dinosaur bones and tracks in place at wonderful Dinosaur Ridge near Morrison. Or, you can visit dinosaurs in one of seven museums around the state, beginning with the Denver Museum of Nature and Science. And, have you seen CU-Denver’s Track Museum just down the street from the Convention Center?

If dinosaurs aren’t your bag, we have the world’s only known fossil tsetse flies and the world’s oldest fossils of ferrets, cheetahs, and roses. Or, perhaps you prefer 300- million-year-old fish poop and cockroaches . The diversity, abundance, and preservation of insects at Florissant Fossil Beds National Monument are unparalleled. They even have giant Sequoia stumps. And, of course, the famous Green River Formation holds world class fossils in addition  to the worlds’ largest oil shale resource.

Welcome, and enjoy experiencing Colorado!

anticline 2009
This syncline/anticline pair is exposed above the Gypsum exit ramp from I-70 and is in Penn-Perm evaporites of the Eagle evaporite basin. UTM 332632E, 4391095N. Photo by Vince Mathews, CGS
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