Volcanic mountains

Four Colorado volcanic sites that provide insight into the state’s historic past

After 50 years of little activity, the Cumbre Vieja volcano in La Palma, Spain sent a plume of toxic smoke into the sky in 2021. The eruption devastated the surrounding area with a barrage of ash and molten lava which did not end for 85 days.

Natural disasters like this may seem quite remote from Colorado, but did you know that the Centennial State is home to several volcanoes? In fact, the state’s volcanic past is largely responsible for the diverse topography that can be found in Colorado today.

Here is a brief overview of some volcanic sites that are worth mentioning:

1. Caldera de La Garita

La Garita Caldera is a 22 mile wide and 62 mile long depression in the San Juan Mountain landscape. Some scientific accounts suggest that the site was home to the largest volcanic eruption in Earth’s history.

A caldera is formed when an eruption caused by the pressure is so powerful that the volcano itself collapses as a result.

The eruption of La Garita Caldera occurred around 28 million years ago. “… he created the San Juan Mountains we know today by completely destroying the volcanoes that were here before,” the United States Geological Survey (USGS) said in a report.

“La Garita made a hole in the state of Colorado that you could have seen from space, a glowing sore as large as all of Mineral County,” the report read.

Today, La Garita Caldera is considered extinct, but its potency can still be seen by the dramatic geological changes it has left behind.

2. Dotsero

Could Colorado's only active volcano erupt again soon?  1

This enlarged aerial image gives a better overview of the shape of the Dotsero crater. Photo credit: @ 2019 Google Maps.

Dotsero – located in northwest Colorado near the junction of the Eagle River and the Colorado River – is Colorado’s last active volcano.

For a volcano to be considered extinct, it cannot have erupted within the past 10,000 years. Dotsero last erupted just 4,152 years ago.

Dotsero marr is about 700 meters wide and about 400 meters deep.

“A maar is a large, low-relief volcanic crater formed by shallow explosive eruptions. Explosions are usually caused by the heating and boiling of groundwater as magma invades the water table. Maars often fill with water. to form a lake, “according to the USGS said on their site.

Although an eruption is not expected anytime soon, the USGS has classified Dotsero as a moderate threat.

Today, the site attracts many hikers, and the lava flow from the latest eruption is actually crossed by drivers on I-70.

3. Huerfano Butte

Butte Huerfano

Photo credit: Maxfocus. Photo file. (iStock).

The Huerfano Butte is a volcanic plug located approximately 10 miles from Walsenburg, Colorado, in Huerfano County. It has been called “the volcano that never existed” because despite its volcanic potential, there is no geological evidence that it ever erupted.

A volcanic plug or neck forms when magma solidifies inside the vent of a volcano.

“Seen from a distance, Huerfano Butte appears to be a volcanic pass, but there is no evidence that the magmas associated with Huerfano Butte have vented to the surface,” SpanishPeaksCountry.com said in a report.

Today, volcanic activity is unlikely to return to the cap.

4. Guffey Volcanic Center

Scientists believe that 34 million years ago, the Guffey Volcanic Center, located in County Teller and near Pikes Peak, housed a series of stratovolcanoes similar in strength and structure to Mount Saint Helens.

“When these volcanoes erupted, they were sending lava and debris flows into the paleovalleys below. McIntyre Mountain and Witcher Mountain are remnants of these massive flows,” the National Park Service (NPS) said in a report. article about the center.

The Guffey eruptions sent lahars – volcanic mud flows – into the surrounding valleys, the results of which can still be seen today.

“A lahar flowed east from the slopes of the Guffey volcanic center. There it crossed the stream of the Florissant paleovallée, blocking the flow and creating Lake Florissant,” the NPS said.

Another flow flooded the valley and petrified the stumps of the redwoods that once grew there. Those Upper Cretaceous the stumps can still be visited today, seen by visitors along with a number of fossilized plants and insects.

Hike through a petrified forest on this Colorado trail

The Great Stump, as it is called at Florissant Fossil Beds, rests next to the Petrified Forest Loop Trail. Only one redwood tree remains from around 34 million years ago, when this part of Teller’s country looked more tropical. Photo credit: Seth Boster, The Gazette

Here are a few other places to visit in Colorado that have volcanic histories:

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