UNLV geologist advocates for preservation of state’s own piece of the Grand Canyon

Frenchman Mountain isn’t the easiest hike in Las Vegas, but the sharp incline and oppressive heat don’t deter UNLV geologist Steve Rowland from revisiting the place he’s dedicated much of his career to studying.

The paths to the summits of the Frenchman Mountain-Rainbow Gardens area start out as loose, gravelly trails but give way to layers of rock in starkly contrasting colors and composition.

Jagged rocks jut out at sharp angles, leaning away from Las Vegas to the west and toward Lake Mead to the east, reflecting billions of years of tectonic plate movement.

If you have a question about the site, chances are Rowland’s got the answer.

The mountain is located on property managed by the Bureau of Land Management in northeast Las Vegas, about 3 miles from Nellis Air Force Base.

When Rowland was hired as a faculty member at UNLV in 1978, his curiosity took him for the initial time to Frenchman Mountain.

“Frenchman Mountain certainly caught my interest,” he said. “The Great Unconformity was right there.”

The mountain is full of history, Rowland said. He spoke earlier this summer at a lecture hosted by Wetlands Park Friends about the importance of preserving the unique geological history of Frenchman Mountain from the region’s urban sprawl.

“There’s no other place on earth that has a more complete, more accessible interval of Earth history than Frenchman Mountain,” said Rowland, who also leads schoolchildren on field trips to the site.

About 15 million years ago, during the Miocene Period, the land that would become Frenchman Mountain was much closer to the Grand Canyon, he said. Tectonic plate activity pulled the mountain about 40 miles to the west, which is why its rocks are noticeably tilted about 50 degrees to the east, he said.

Rowland said he partnered with researchers from the Denver Museum of Nature and Science to sample soil from different layers of Frenchman Mountain, giving the name Frenchman Mountain dolostone to a dolomite-heavy rock layer. The dolostone layer continues from the mountain to the Grand Canyon.

“You have a piece of the Grand Canyon right here. It’s so accessible,” Rowland said.

When Rowland began studying the dolostone layer in the 1990s with his then-student, now co-researcher Slava Korolev, there was no way to tell how old the layer was. There were no fossils in that part of Frenchman Mountain and no other clues, he said.

Through a modern process called carbon isotope stratigraphy, James Hagadorn of the Denver Museum of Nature and Science was able to take Rowland’s samples from Frenchman Mountain and the Grand Canyon and determine the similar layers were all the same age.

The dolostone layer formed over 7 million years, about 500 million years ago, Rowland said.

“We couldn’t precisely correlate rocks from Frenchman Mountain with anywhere else … and of course, the continents have drifted since then,” Rowland said. “We weren’t able to make it more precise than that until we had carbon isotope work done.”

Rowland said the youngest layers at the top of the Grand Canyon have been eroded, but Frenchman Mountain and Rainbow Gardens give a clear look at Mesozoic, Triassic, Jurassic and Miocene period rocks.

The Great Unconformity, where the continuity of different rocks from different periods gets interrupted by a layer of sandstone, is also found in both locations. Rowland said the layers of rocks on either side of the unconformity are about 1.2 billion years apart in age.

“They were exposed to the earth’s surface (and) the sea level rose and covered that exposed surface with sandstone,” Rowland said.

While the summits reward hikers with a view worth the exertion, too often the trails are strewn with trash and broken glass.

Rowland said the 32,000-acre area is designated by the BLM as an “area of critical environmental concern,” but that status doesn’t afford it much protection.

Bertha Gutierrez, the Nevada program director for the Conservation Lands Foundation, said the Nevada Legislature in 2021 passed a resolution urging Congress to protect the land.

Advocates are calling for the site to be designated a national conservation area, national recreation area or national monument.

In 2022, Get Outdoors Nevada launched a petition for the site to be named a national monument.

“A lot of the community really loves this area,” Gutierrez said. “There’s a lot of recreation that happens there.”

Rowland said that because the area is close to Lake Mead National Recreation Area, some proponents have suggested extending the area to include Frenchman Mountain and Rainbow Gardens under National Park Service protection.

Rowland said he was part of an effort to designate the area as a protected interpretive site in 1995, but vandals destroyed the plaques he and others raised money for. He said ultimately he hopes the area receives protection for its educational, historical and cultural importance.