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Flooding and erosive flows following a 2004 rainstorm caused this bridge collapse in El Paso County. East Sand Creek had been

Case study: Fluvial Hazard Zone

“The Fluvial Hazard Zone (FHZ) is defined as the area a stream has occupied in recent history, may occupy, or…

ON-001 Colorado Earthquake and Fault Map

The Great Colorado ShakeOut 2022

It’s coming up in less than four weeks! The Great Colorado ShakeOut is a public earthquake drill that takes place…

MS-53 Colorado Stratigraphy Chart, from Robert Raynolds and James Hagadorn, 2017. Credit: Colorado Geological Survey and the Denver Museum of Nature and Science.

MS-53 Colorado Stratigraphy Chart

A collaboration between the CGS and the Denver Museum of Nature & Science (DMNS) has…

Earthquake damage: significant cracking and displacement in adobe wall of garage, Trinidad, Colorado, August 2011. Photo credit: T.C. Wait for the CGS

The Great ShakeOut

The origins of The Great ShakeOut project lie, unsurprisingly, in Southern California, one of the more…

Excerpt drone shot from Dr. Christian Shorey's

Earth Explorations vlog/podcasts

Dr. Christian Shorey—Teaching Professor of Environmental Science and Climatology in the Geology and Geological Engineering Department…

Pyrite, a metallic sulfide mineral, found in the dump of the Allan Emory Mine in Summit County, Colorado. Photo credit: Colorado Geological Survey.

Case Study: NARD

Are pristine mountain waters always clean and pure? Can streams unaffected by human activities and livestock influences be unfit…

Skyline Drive, a one-way road along Skyline Ridge (a hogback of Dakota sandstone) northwest of Cañon City, Colorado, features spectacular views of geological and paleontological features. Seen here, geologist Dr. Adam Jackson introduces the track impressions of a group of 30-foot-long, six-ton, armored Ankylosaurs. Photo credit: Cindy Smith.

Fremont County geologic attractions

Fremont County, two hours south of Denver, is located on the south-central Front Range of Colorado in a geological region…

North Table Mountain stands between Golden and the wider Denver metro area in the background. Photo credit: Vince Matthews for the CGS.

Golden Rocks: The Geology and Mining History of Golden, Colorado

We’ve received the go ahead to help distribute this marvelous (and FREE!) 100+ page digital publication from the talented…

The Flatirons overlooking Boulder, Colorado are comprised of once flat-lying Permian Fountain Formation sedimentary rock that were tilted to 50 degrees by the orogenic uplift of the Rocky Mountains. Photo credit: Vince Matthews for the CGS.

Unfolding the Geology of the West

Our collaborators and friends up in Boulder at the Geological Society of America (GSA) are making…

Munroe Quarry near Livermore, Colorado in Larimer County, which produces gypsum from the Permo-Triassic Lykins Formation. Photo credit: Colorado Geological Survey.

Case Study: Lykins Formation

Small but significant areas of Colorado are underlain by bedrock that is composed of evaporative…

An expansive view of most of Colorado looking from the south-south-west from the International Space Station (ISS). Photo credit: NASA.

NASA Earth Observatory

One of our favorite online feeds is from the NASA Earth Observatory along with their…

Interstate-70 running through Glenwood Canyon is one of the most spectacular segments of the US Interstate system. Photo credit: Vince Matthews for the CGS.

The Glenwood Canyon Highway

This recent RMPBS/Colorado Experience video traces the history of transportation through Colorado’s spectacular Glenwood Canyon. It…

Pierre Shale (gray) exposed along St. Vrain Creek in Weld County, Colorado. Photo credit: Stephen Keller for the CGS.

Recent reports published

OF-20-11 Alkaline Complexes of the Wet Mountains Area, Colorado: A Geological Summary, Bibliography, and Data Compilation…

On the Cumbres & Toltec Scenic Railroad Geology Train trip, there will be plenty of opportunities to debark and get close-up views of the fascinating geology along the way. Photo credit: CTSRR.

Cumbres and Toltec Geology Train

We just found out about this year’s Cumbres & Toltec Geology Train adventures in southwest Colorado and northwest New Mexico.

Headscarp of an ongoing landslide in the now-shuttered Pikeview Quarry in El Paso County, Colorado, September 2009. Photo credit: T.C. Wait for the CGS.

Welcome to the CGS RockTalk blog

We’ve decided to revive one of our most popular print publications — RockTalk — as a blog so that…

By August 2005, the entire rock slope had been laid back to 45 degrees along with the installation of stability-enhancing rock reinforcement anchors. Photo credit: Vince Matthews for the CGS.

Case Study: Clear Creek Canyon rockslide

Rockfalls and rock slides are common along transportation corridors in the Rocky Mountains. Clear Creek Canyon just west of Golden…