Hurricane Fault responsible for some of Southern Utah’s most iconic views

ST. GEORGE — A fracture in Earth’s crust transforms the landscapes in its midst.  It uplifts the land to its east and the Virgin River cuts through layers of dirt and rock, carving deep, narrow canyons. Elsewhere, headwaters run down red stone, sculpting an amphitheater as it flows toward the valley below.

Geologic formations at Cedar Breaks National Monument, Utah, Aug. 30, 2022 | Photo by Alysha Lundgren, St. George News

These iconic places wouldn’t exist without the Hurricane Fault.

Located in Southwest Utah, this natural wonder is a fracture in Earth’s crust that has shifted, Casey Webb, a geology professor at Southern Utah University, said in a YouTube video.

According to a Utah Geological Association 2019 publication, the fault is 155 miles long, stretching from south of the Grand Canyon to Cedar City.

“The Hurricane Fault is one of the most prominent geologic structures in southwestern Utah,” the document states.

Webb told St. George News that the Earth’s crust in the West’s Basin and Range Province is being pulled apart, causing it to thin. The stress of this action is causing fractures to form.

The National Park Service stated the earthquakes occurring along the fault over the past 10 million years lowered land to the west while uplifting the east side.

Fractures running parallel to the Hurricane Fault can be seen in this Satellite image of Zion National Park | Image courtesy of Google maps, St. George News

The fault forced up the Markagunt Plateau approximately 2,000-8,000 feet, Webb said. The rise in elevation steepened water flows, like the Virgin river’s, increasing the downcutting power and speed necessary to incise the bedrock to form steep and narrow canyons at Zion National Park.

“Without that fault, this canyon isn’t there,” he said. “Doesn’t exist.”

According to the National Park Service, the uplift was “not chaotic, but (a) very slow vertical hoisting of huge blocks of the crust” causing Zion to rise from near sea level to as high as 10,000 feet.

“Uplift is still occurring,” according to the website. “In 1992 a magnitude 5.8 earthquake caused a landslide visible just outside the south entrance of the park in Springdale.”

Zion National Park as seen from the Kayenta Trail, Zion National Park, Utah, date not specified | Photo by Alysha Lundgren, St. George News

While the rocks at Cedar Breaks are ancient, the National Park Service said, the infant landscape is “in a constant state of change.”

Before the uplift, the monument’s rock layers were buried deep within the Earth, “immune to the elements,” the website states.

“Only after the Hurricane Fault thrust the rocks into the sky were water, ice and gravity able to vigorously attack them and begin carving their masterpiece,” the park service states.

However, Cedar Breaks National Monument was not downcut by a major stream or river, Webb said. Instead, the monument’s amphitheater was eroded by Coal Creek’s headwaters, which eventually flow through Cedar City.

While the Virgin River has more of a “set path,” the watershed at Cedar Breaks can change rapidly and follows more routes, creating a more rounded, stepped shape, Webb said.

In this file photo, hikers explore The Narrows in Zion National Park, Utah, date unspecified | Provided by the National Park Service, St. George News

Additionally, the “tensional stress” of the Earth’s crust thinning causes fracture joints and faults throughout Zion National Park. These cracks run parallel to the Hurricane Fault and are pathways to erosion, he said.

The fault remains active and produces earthquakes that can be detected with seismographs, Webb said in the video. The fault is large enough to produce earthquakes measuring 6.0 or more on the Richter scale.

To learn more about Zion National Park’s geology, click here. To read about how Cedar Breaks National Monument was formed, click here. To hear more about the Hurricane Fault, watch Webb’s video here.

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Copyright St. George News, SaintGeorgeUtah.com LLC, 2022, all rights reserved.

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