EL MORRO NATIONAL MONUMENT, NM (AP).- For centuries, Spanish explorers, U.S. Army troops, wagon train emigrants and railroad surveyors carved their names on a huge sandstone outcrop in what's now a national monument famed for those inscriptions.
But the softness of the rock that allowed names to be chipped into the cliff at El Morro National Monument also is letting those signatures erode jeopardizing the history the park is meant to protect.
Over the years, officials have reattached fallen inscriptions, developed grout to keep moisture out of cracks and experimented with coatings to prevent signatures from wearing away.
El Morro Spanish for headlands became a stopping point because of its reliable water, a pool fed by runoff from the cliff.
Hundreds of travelers left their names some famous; others with stories behind them.
"All those things together make them historic," said Steve Baumann, archaeologist at the northwest New Mexico monument.
"Pasa por aqui," wrote provincial governor Don Juan de Onate in 1605, "passed by here."
Onate's inscription, one of the earliest, partially covers one of the prehistoric American Indian petroglyphs also carved on the rock.
Don Diego de Vargas, who led the Spanish reconquest of New Mexico in 1692 after a Pueblo Indian revolt, signed his name that year, saying his conquest was "for the Holy Faith and for the Royal Crown ... at his own expense."
Twelve-year-old Sallie Fox who came through in a wagon train wrote her proper name, Sarah, in 1858.
The deeply incised, printer-like inscription of "P. Gilmer Breckinridge, 1859 VA," is marred by a chip biting into the C in his last name and edging up to the 9 in the date.
Breckinridge came through El Morro with 25 camels from a short-lived Army experiment. He would later resign, join the Confederacy and die in the Civil War.
The same expedition included "E. Pen Long, Baltimore," who left a large signature in flowing, perfect old-fashioned script.
The group, doing reconnaissance, "had all kind of tools with them for marking features on the landscape for mapping purposes," Baumann said. "They would have been well-equipped to make some nice inscriptions."
Although the expedition was in 1857, Breckinridge didn't carve his name until another trip in 1859.
He wasn't the only person to visit El Morro more than once.
"That's the case with Onate," Baumann said. "He was here three times before he left his name."
Artist R.H. Kern carved his name in 1849 and 1850.
Kern and Army Lt. J.H. Simpson, the first English signatures, recorded that they "visited and copied these inscriptions, September 17-18, 1849." They misspelled inscriptions, leaving out the "r."
The largest concentration of signatures comes at the rock's north point, where a ledge now mostly eroded made it easy to write up high. Inscriptions range from Spanish explorers to employees of the Union Pacific railroad in the 1860s.
Park officials removed some inscriptions in the 1920s, deciding anything carved after the monument's establishment in 1906 was graffiti.
The effort didn't get everything. A cove closed to visitors has Army inscriptions dated around 1907.
El Morro has been working with the University of Pennsylvania on preservation since the early 1990s. The latest phase will produce a conservation plan next spring.
The park is "not a museum artifact you can put under glass and keep from changing," said associate professor Randall Mason, who teaches in the school's graduate historic preservation graduate program.
The rock's condition, the soil, the affect of water and the landscape have been studied but "what's missing is what connects all those aspects and the dynamics between them," he said.
Preservation efforts aren't new. In 1926, El Morro's manager experimented with different coatings over the word "colorless" he'd carved on a boulder.
Nothing works completely, Baumann said.
"It's hard to calculate what's going to happen in 50, 100 years," he said. "You try and do something that you think will last, will help at the time and will continue to last and will do as little harm as possible. Ideally, something reversable."
In places, sandstone has split, allowing water in. Insect burrowing is a threat, as is sandstone disintegration and clay washing out, draping over inscriptions.
Even the famed pool could be damaging inscriptions around it. The pool was 11 feet deep this month, but its depth was closer to 3 feet in previous centuries, probably with a sandy beach that let people get close to carve, Baumann said.
"One of the unfortunate consequences of raising the pool is that it appears to have affected these inscriptions, that it seems to have accelerated their deterioration," he said.
When a ranger who worked at El Morro around the '40s returned, he "looked around the pool and said, 'My God, what happened to the inscriptions?' So that fast, we saw some change," Baumann said.
Since 2006, the Center for Desert Archaeology in Tucson, Ariz., has used a laser to scan inscriptions, offering much more detail than photographs. Recent scans can be superimposed on earlier ones, highlighting changes.
It's allowing park officials to assess the rate of erosion for the first time.
"That's a question we want to get at ... how fast are they eroding at different places," Baumann said.
Then there's graffiti up to 40 incidents a year. This year was particularly bad, with 11 in June alone. Graffiti is a violation of the Archaeological Resources Protection Act and carries stiff fines.
A sign by Inscription Rock warns: "It is unlawful to mark or deface El Morro."
"What we're trying to do is preserve this as it was, historically," Baumann said. "And a lot of other inscriptions that occur now graffiti it sort of detracts from that historic feel."