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