Ancient Native American petroglyphs in Bears Ears national monument could be damaged or ruined following the Trump administration’s announcement earlier this week to reduce the park by more than 85%, according to artnet News.

There are an estimated 100,000 cultural and archaeological sites in Bears Ears, according to Utah Diné Bikéyah, a coalition of Native American groups working to protect the land.

The move opens up vast swaths of the monument to potential industrial activity, which could threaten rock paintings and engravings that first appeared thousands of years ago, according to artnet News.  

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“Roads, well pads, and open pit mines will obliterate the sites,” David Whitley, a prehistoric archaeology expert at ASM Affiliates, told artnet News. “Pollution generated by these activities will quickly degrade the remainder.”

For Native American groups in the region, the decision to reduce the park feels like a betrayal, according to an op-ed by the Navajo activist Julian Brave NoiseCat, since they had been lobbying to safeguard the sacred area for decades.

Other Native Americans fear that stripping federal protections from the land will lead to artifacts being looted or damaged by tourists, NPR reports.

Read More: Trump Wants to Mine, Frack, and Log on Public Lands. Here’s Why That Can’t Happen.

“What I'm afraid's going to happen is every pot hunter, every grave robber, every artifact person that's trying to make a buck will basically inundate the place and dig up what's left,” Shaun Chapoos, a tribal leader involved in the effort to protect Bears Ears, told NPR.

This looting and recreational destruction of artifacts has already begun, according to National Geographic. Since Bears Ears was established in 2016, the area has seen a spike in tourism. Most of these visitors are unsupervised and unaware of the area’s cultural and scientific importance, National Geographic reports, and go on to damage precious sites.

Chapoos added that this everyday impact could then give way to destructive industrial activities like fracking and coal mining.

“They'll destroy irreplaceable pieces of history,” Chapoos said. “And I'm afraid that, you know, they'll try to speed up the process to do fuel development as far as fossil fuels without following legal process. And that always leads to disaster.”

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The reduction announcement included Bears Ears and another Utah National Monument, Grand Staircase-Escalante, established in 1996, in what is the largest reduction of public lands in US history.

National monuments are created by presidents under the Antiquities Act, unlike national parks, which are created by Congress and have stronger protections. The Antiquities Act doesn’t say that presidents have the authority to reduce or remove national monuments, only to grant them.  

Read More: 12 Gorgeous Photos of the Monuments That Will Be Shrunk by Trump's Executive Order

Native American groups, along with environmentalists and recreation industry groups, will challenge President Trump’s decision on the grounds that it was illegal and that only Congress can reduce or remove monuments.

The Trump administration argues that the reduction was legal and that shrinking the monuments is just a way to reverse federal overreach.

A lawsuit filed on Wednesday will pit these two perspectives against each other and could set an important precedent that shapes how public lands are managed in the future, according to the New York Times.  

In the meantime, the fate of ancient art hangs in the balance.