text: The fill from two of the stoneholes has been carbon dated to between 2900 and 2600 BCE ( 3870 + \/ -90 , 4130 + \/ -90 )
simplified: The fill from two of the stoneholes has been carbon dated to between 2900 and 2600 BC ( 3870 + \/ -90 , 4130 + \/ -90 )