The waves at Pine Trees surf break constantly reshape the shoreline. And when really big surf comes in, the resulting erosion can briefly uncover Hawaiian petroglyphs.
That's exactly what happened Thursday, and resident Avi Salvio was lucky enough to snap photos of two petroglyphs she spotted before they disappeared under sand again less than 24 hours later.
"They're a really special thing to see, but they disappear really fast," Salvio said.
Normally, you wouldn't even see the lava rock on the beach. That's because it's typically covered with at least 10 feet of sand.
University of Hawaii anthropology professor James Bayman said petroglyphs were created by pecking one rock with another rock.
Because the carvings at Pine Trees are rarely seen, not much is known about them. But Bayman says they could easily date back several hundred years.
It's been reported there are as many as 70 carvings chiseled into the lava rock there, mostly depicting human like figures and dogs.
Bayman says dogs were very meaningful in Hawaiian culture; their meat was reserved for men with a very high status.
In 42 years, Adam Salvio says he's only seen the carvings four times.
"As you're watching during the day the sand will cover them up and you try to sweep the sand off of them so they'll stay up a little longer," said Adam Salvio.
He always appreciates the rare glimpse of history.
"You're realizing that people were here so long ago and you know they were at your same beach and you're just reliving history again and you're doing the same thing that they've done, playing in the same area. It's pretty cool."
Residents say there are more petroglyphs at Rock Piles and Ke Iki Beach.