If you go What: Presentation on lithophones by Marilyn Martorano When: 11:30 a.m. to 12:30 p.m. Nov. 8 Where: Community Room at Front Range College’s Boulder County Campus, 2121 Miller Drive, Longmont Cost: Free A handful of unnaturally elongated stones sat on display at the Great Sand Dunes National Park and Preserve museum for decades with no one ever knowing exactly what they were.

Many were too big and perfectly shaped to be used for a mortar and pestle or metate. Without any sharp edges, it also seemed unlikely they were used for some kind of weapon. Utterly confounded, Longmont-based archaeologist Marilyn Martorano finally struck the ancient rocks with a mallet and was stunned to hear a metallic ringing emit from the solid rock.

“We had seen them in the museum for years and it just bugged me,” she said. “I had sort of given up and I had to return these stone to the museum the next day so I thought, ‘well, this is a crazy idea, but what the heck’ and grabbed one of my daughter’s drumsticks in the car and started tapping them. What I heard blew my mind.”

With several stones to play on, Martorano soon discovered that depending on their size, each stone emitted different notes and when laid out together they made a kind of ancient xylophone or marimba. Like a marimba, each stone is roughly four and a half times longer than they are wide and had acoustical nodes notched at the one-quarter mark on either end.

After her accidental breakthough in 2013, Martorano knew she needed more time to study these relatively unknown stones and prove her theory. Just a year later, after partnering with the nonprofit advocacy group, Friends of the Dunes, she was awarded a grant from the History Colorado Center’s state historical fund.

Over the next three years she found that even though the stones, some of which dated back as far as 6,000 years, have been found on every continent except Antarctica, almost no one knew much about them.

“Nobody I know in archeology here in Colorado ever talked about sound as a function,” she said. “I think that’s why it took so long to figure it out. Back in 2013 there was hardly any information about them online”

Discovering their use, however, was just the beginning.

“There’s no doubt in my mind that whoever fashioned these stones understood acoustical properties, that there are places you can hit where it will resonate and there are certain mathematical ratios where another pitch will happen,” said Michael DeLalla a professor of musicology at Front Range Community College who also owns and records for Falling Mountain Music. “And, if they understood that, in what other parts of their lives did those ratios work?”

For instance, ancient Greeks understood those mathematical ratios not only in terms of music, but in terms of nature. Pythagoras didn’t just devise the Pythagorean theorem, he created the first western scales based on those mathematical ratios.

“We all grew up with these burlesque ideas of about people back then and how crude and uncivilized they must have been,” DeLalla said. “This hypothesis holds so many levels of sophistication for me. These people were not just concerned with survival, they had many of the same intellectual pursuits and interests and curiosities and sophistication as we do.”

For example, with some of the stones weighing more than 10 pounds it seemed unlikely the hunters and gatherers roaming the United States at the time would have the ability to haul these large stones where ever they went. Also found in the Sahara and the Sand Dunes sticking straight up out of the sand, Martorano believes the stones were not only used as musical instruments but also as a sort of geographical marker.

“We know through ethnographic data that different groups in historic times would meet at certain times of the year,” she said. “This may sound kind of funny, but my idea is that they were coming together for a celebration and wanted to have music there. It was a rock concert.”

With such insights Martorano sees the discovery of these “singing rocks” as a sort of de-fogged window into the past. If researchers can better understand how the rocks and the lithophones they comprised were used, she said, it could help better define who these people were and how their society operated.

“I think having more broad knowledge about these lithophones will cause more to be found, perhaps in a context we can date and glean more information from,” she said. “That the great part about sand, the wind is always unearthing things beneath it, so I think we’re just at the beginning.”

John Spina: 303-473-1389, jspina@times-call.com or twitter.com/jsspina24