The tides have revealed a gallery of petroglyphs on a beach in Hawaii that experts say have never been recorded before.

The glyphs are pecked into the sandstone floor of the beach at Waianae, on the western coast of Oahu, which is typically covered with a thick blanket of sand.

But in late July, tourists arrived at the beach to find the bedrock exposed and the rock festooned with a series of human-shaped figures, their feet pointing toward the ocean.

Most of the petroglyphs are about a third of a meter (about 1 foot) tall, but at least one is 1.5 meters (5 feet) in length.

U.S. Army archaeologist Alton Exzabe, who was called to the site to survey it, said that the glyphs have likely been exposed before, thanks to similarly random acts of time and tide, but they’ve never been recorded before by scientists.

“What’s exciting for me is, I grew up coming to this beach, and now as an archaeologist working for the Army, helping to manage this site, we discovered these petroglyphs that have never been recorded,” said Exzabe, in a press statement.

“Some people have said they’ve seen them before, but this is quite a significant find.”

At least 17 petroglyphs have been discovered so far, spanning more than 18 meters (60 feet) of sandstone.

The most salient of the glyphs is a nearly-life-size anthropomorph, complete with articulated fingers and toes.

“The ones with the fingers, for me, are pretty unique,” Exzabe said.

“I believe there are some elsewhere with fingers, but fingers and hands are pretty distinct, as well as the size of them.

“We find a lot of petroglyphs that are a foot or so tall, but this one measures four to five feet from head to toe. It’s pretty impressive.”

Exzabe added that this kind of find is a first for military property on the island.

“The Army in Hawaiʻi manages several thousand archaeological sites, but this is the first one with petroglyphs directly on the shoreline,” he said.

However, similar beach-bench petroglyphs have been found elsewhere on Oahu and throughout the Hawaiian Islands.

In 2014, a freak winter storm brought on by El Niño revealed a series of petroglyphs etched into the volcanic bedrock at Waimea, on Oahu’s North Shore. [See the briefly-exposed glyphs: “Monster Surf Exposes Rare Petroglyphs in Hawaii“]

There, more than 70 images were found, mostly of humans and dogs. And although that rock art had been recorded before, it hadn’t been seen since at least 2010.

By contrast, even locals at Waianae do not appear to have been aware of the newly-recorded petroglyphs there.

Glen Kila is a descendant of the first inhabitants of Nene’u, a beach settlement just north of the site, and he, too, was unfamiliar with the rock art gallery that appeared just a short walk from his house.

He added that the significance of such glyphs is best understood by the cultural group that made them.

“These petroglyphs can only be interpreted by the lineal descendants who are familiar with its history and culture,” Kila said, in the same press statement.

“It’s very important to know about the lineal descendants of the area and their understanding of these petroglyphs.”

Regarding the meaning of the images, he said: “They record our genealogy and religion.” [Learn about recent finds from Hawaii’s ancient history: “Prehistoric Temples on Maui Reveal Origins of Island’s First Kingdom“]

Archaeologists believe Native Hawaiian petroglyphs, known as kii pohaku, have served many functions, from telling stories, to providing directions to passersby, to commemorating significant local events.

And the Waianae images were probably carved a century or two before the first European contact with the islands.

According to Hawaii’s Department of Land and Natural Resources, the glyphs are believed to be about 400 years old.

Given the uniqueness of the Waianae petroglyphs — and the fact that they’re the newest to the archaeological record — Exzabe and his colleagues documented them quickly before the sands returned and obscured them from view once more.

They’re now all but gone.

But the state’s historic preservation officer said that his office intends to protect the images so their legacy can remain unspoiled.

“They are an important part of Hawaii’s culture,” said Alan Downer, with Hawaii’s historic preservation office.

“And while sands have covered them again, in time they will reappear, and we want to make sure people know that they are fragile and culturally sensitive and should only be viewed, not touched.”