A layperson's simple observation may help solve a Stonehenge mystery that scientific expertise couldn't. A historic preservation worker noticed that the grass didn't grow so well in certain areas near the ancient monument, the BBC reports. It's possible that giant stones were once placed there, suggesting that the outer ring of the site may once have been a full circle. Tim Daw made the discovery while gazing at the grass, "thinking we needed to find a longer hosepipe to get the parched patches to green up." That's when he had "a sudden lightbulb moment."
"I remembered that the marks were where archaeologists had looked without success for signs that there had been stone holes, and that parch marks can signify them," he notes. An earlier scientific survey of the site sought to investigate the full-circle theory, which has divided experts, the BBC notes; the survey found no sign of a full circle. "I am still amazed and very pleased that simply really looking at something that tens of thousands of people had unwittingly seen can reveal secrets that sophisticated machinery can't," Daw adds. Dry, hot periods can make such "parch marks" show up, the BBC notes: In the past, the Telegraph reports, such weather has revealed remnants of Roman forts and other ancient sites. (Another big Stonehenge discovery emerged earlier this year.)