Archaeologists say they've discovered what they believe is the world's oldest lunar calendar in a field in Scotland.

Excavations of a field in Aberdeenshire uncovered a series of 12 pits that appear to mimic the phases of the moon and mark out lunar months, the BBC reported.

Researchers at the University of Birmingham said the ancient monument was likely created by hunter-gatherers about 10,000 years ago.

If so, the Mesolithic calendar is thousands of years older than previous known formal time-measuring monuments created in Mesopotamia, they said.

Experts who examined the pits said they may have contained a wooden posts, aligned on the midwinter sunrise to provide the hunter-gatherers with an annual "astronomic correction."

"The evidence suggests that hunter-gatherer societies in Scotland had both the need and sophistication to track time across the years, to correct for seasonal drift of the lunar year and that this occurred nearly 5,000 years before the first formal calendars known in the Near East," Birmingham landscape archaeology Vince Gaffney said.

"In doing so, this illustrates one important step towards the formal construction of time and therefore history itself."

The findings have been published in the journal Internet Archaeology.