Ought to (or May) Trump Be Added to Mount Rushmore?

President Trump has made no secret of his fondness for Mount Rushmore and his desire to join its rock-star lineup.

During his first term, Mr. Trump told Kristi Noem — then a U.S. representative from South Dakota, now Mr. Trump’s Secretary of Homeland Security — that his “dream” was to be on Mount Rushmore. She later gave Mr. Trump a model of Mount Rushmore with his face on it.

The idea has resurfaced since Mr. Trump returned to office. A congresswoman from Florida sponsored a bill in January to “direct the Secretary of the Interior to arrange for the carving of the figure of President Donald J. Trump on Mount Rushmore National Memorial.” It was referred to the House Committee on Natural Resources, which has yet to act on it.

In March, Interior Secretary Doug Burgum said in an interview with Lara Trump, Mr. Trump’s daughter-in-law, that “they definitely have room” for Mr. Trump’s face on Mount Rushmore.

Wait. Is this possible?

As with all things Trump, it can be hard to decipher the difference between everyday rhetoric and future action. But those in charge of the memorial are taking such overtures seriously.

The National Park Service, which oversees Mount Rushmore National Memorial, and which is currently led by Mr. Burgum, has cited two reasons that more faces cannot be added. First, it considers Mount Rushmore to be a completed work of art. Second, there is no room. “The carved portion of Mount Rushmore has been thoroughly evaluated, and there are no viable locations left for additional carvings,” the park service said in a statement.

Those are the frames for the debate, now and in the future. One is philosophical. The other is geological. One is a question of should; the other is a question of could.

Mount Rushmore is a cultural touchstone, American shorthand for the best of the best. “Who belongs on your Mount Rushmore?” is the opening to a debate on any niche subject, as if we might carve such a monument to athletes, musicians or writers.

But the real thing is about presidents. Gutzon Borglum, the sculptor who designed the massive carvings and oversaw their construction for 14 years, starting in 1927, chose the four presidents and their precise locations.

What would he make of President Trump? And where would he put him?

It was a historian named Doane Robinson who dreamed of carved faces in the Black Hills as a way to draw tourists. He envisioned Western heroes, like Wild Bill Hickok and Sacagawea, on spires along a winding road in an area called the Needles. They probably would have looked like giant Pez dispensers.

Mr. Borglum was recruited. Already an accomplished sculptor, he became enamored of the broader canvas of Mount Rushmore, named for a New York lawyer who was scouting tin mines in 1885. “A mountain of granite rock that rose above the neighboring peaks,” Charles Rushmore described it then.

Mr. Borglum soon homed in on memorializing former presidents to represent the nation’s first 150 years.

Now the United States is a year from turning 250, and those who wish to preserve the memorial are nervous about the motivations of those who might change it.

“You wouldn’t add another face to Borglum’s Mount Rushmore just like you wouldn’t add one to da Vinci’s ‘Last Supper,’” said Dan Wenk, who was the superintendent of Mount Rushmore National Memorial from 1985 to 2001. “But I recognize that these types of ideas are no longer off the table.”

In the past, some have pushed for Franklin D. Roosevelt, others for John F. Kennedy. The strongest push, before now, was in the 1990s for Ronald Reagan.

The thought of amending Mount Rushmore faded until Mr. Trump suggested himself. It’s a provocative idea. Historians recently ranked him as one of the worst presidents in American history, while the four on Mount Rushmore are all in the top five.

But plenty are taking Mr. Trump’s Mount Rushmore ambitions at 60-foot-face value. Theoretically, the president could direct his administration to carve his face there. Given his penchant for chipping away at norms, who’s to say that Mr. Trump wouldn’t figure out a way to chip away at Mount Rushmore?

“Fortunately, from my view, and not just for Trump but anybody else,” Mr. Wenk said, “they’re fighting against the reality of the rock.”

Standing in front of Mount Rushmore, as about 2.5 million visitors do every year, it’s easy to imagine where additional faces might be carved.

Could another face go there? Or there? Or even over there?

The answer, again and again, is no, according to geologists and those who have studied Mount Rushmore closely. Or, at least, probably not. Barring some inventive approach — holograms, anyone? — a new face is unlikely.

Even Mr. Borglum’s early visions for Mount Rushmore were denied, again and again, by the secrets inside the rock. Most of Mount Rushmore is granite — Harney Peak Granite, named for the tallest mountain in the Black Hills — but it also has veins of other types of less-carvable rock.

For example, Mr. Borglum’s early plans called for torsos, not just faces, of the presidents. But those were scrubbed when he discovered the dark, flaky, layered schist below the lighter-colored granite, unsuitable for carving.

Harder to see throughout the sculpture are veins of large crystals, called pegmatite, too large and weak to be carved as finely as Mr. Borglum had hoped.

He worked around several veins of rose quartz, including one that forced Mr. Borglum to move Roosevelt tight against Jefferson and narrow his face. Those weaker crystals are why Lincoln’s hair was left unruly, one of many places where the rock was not suited for such delicate sculpting.

The trickiest thing about carving on Mount Rushmore, though, might be the tangled web of fissures, cracks and flakes of various sizes and depths. Many are visible. Look closely at the faces. Some presidents look like scarred victims of a knife fight.

Park rangers note that the reason Jefferson appears to be peering into the distance, beyond the horizon, is not because he represented expansion of a young nation. Rather, flaws in the rock in Jefferson’s right cheek forced Mr. Borglum to tilt Jefferson’s head back and to the left, so that fractures would cut under his nose, not across it.

Those cracks also left a hole in Jefferson’s lip, the one place on the mountain where a piece of granite was added to fill a gap.

Beginning in 1989, scientists assessed the stability of the rock and mapped 144 fractures and other discontinuities on and around the four faces. The intersection of fractures creates blocks, or large chunks, not unlike the pieces of glass in a shattered windshield.

In 1998, a network of gauges was strung across Mount Rushmore to monitor the cracks and blocks. The worry is less about seismic activity (unusual in the area) and more about rock movement during freeze-thaw cycles, both seasonally and from night to day. Horizontal cracks are mostly sealed to keep water out, while vertical cracks are left open to let water drain.

“One of the concerns about an additional face is that you could activate these fractures,” said Paul Nelson, a geomechanical engineer who spent years overseeing the Rock Block Monitoring System at Mount Rushmore. “If you remove material, you could be removing support.”

In other words, he pointed out, a new face next to Lincoln might cost Abe his nose. Nelson concluded that it would be “extremely difficult, if not impossible, to carve an additional face on Mount Rushmore.”

Some of those limitations can be seen from where most visitors notice a polished sculpture.

In this era, imaginations are being stretched and no idea can be dismissed, including at Mount Rushmore. Could smaller versions of presidential heads be carved around the current ones? Maybe, though no one is proposing a 10-foot Trump head sitting on Washington’s lapel or anywhere else.

Could a pre-made carving be attached to Mount Rushmore? If portions of the rock are not strong enough to be carved, they are likely not strong enough to hold something. A cubic foot of granite weighs about 170 pounds. Another material, if it could be adhered, would age differently, beyond other issues.

What about changing one of the current faces into someone new? Not impossible, but those who want to see Mount Rushmore protected take solace in knowing that all four presidents on it remain popular and in good standing.

Perhaps more likely than a fifth president on Mount Rushmore are other ideas already in motion. Mr. Trump himself has proposed a National Garden of American Heroes, a sculpture garden to honor 250 Americans. His administration already has a list of potential honorees, but not a place for them. South Dakota officials are pitching the Black Hills as a home, within view of Mount Rushmore.

Another group is proposing a sculpture garden and learning center in the Black Hills, aimed at “preserving all chapters of the American story” that might align with the president’s vision.

Maybe a monument to Mr. Trump will be a showpiece of one of those nearby projects, rather than on Mount Rushmore itself.

Robin Borglum Kennedy hopes so. She is the granddaughter of Mr. Borglum and the daughter of Lincoln Borglum, who helped his father carve Mount Rushmore and served as the memorial’s first superintendent. She was born in 1941, the year the sculpture was considered complete.

Ms. Borglum Kennedy (no, no relation) is vehemently against any changes to the mountain, now or deep into the future. She sees Mount Rushmore as a historical memorial more than a political one. Her grandfather, after all, chose four men who were already dead.

“It was conceived as a tribute to the ideals of America,” she said, “not to any one man.”

But that’s a matter of philosophy, not science.