A prehistoric deer antler pick found during a 2007 excavation of the Stonehenge Cursusan earthwork located near Stonehengeis displayed by a dig team member in an undated photo.

Radiocarbon dating of the ancient construction tool gives a new date of 3630 to 3375 B.C. for the Cursus, a cigar-shaped ditched enclosure that extends for almost 2 miles (3.2 kilometers).

This shows it was built a thousand years before Stonehenge's massive sandstone structures were erected, archaeologists say.

The monument's two parallel ditches were found to be free of other animal bones or human artifacts, indicating it was a sacred site.

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