Mike Pitts has a timeline on the Richards, Darvill and Parker-Pearson revised chronology for Stonehenge – go to http://mikepitts.wordpress.com/2012/12/01/stonehenge-in-five-easy-stages… … but he adds some uncertainty as it seems a few cremations found there have been C14 dated somewhat earlier than the construction of the bank and ditch. At the moment this remains conjecture, a wisp of a possibility of a future revision of dates, and here are the five stages.
1) 3000-2875BC … the Aubrey Holes, ditch and bank, various postholes and stakeholes.
2) 2500-2400BC … Sarsen trilithons, sarsen circle, double bluestone circle, station stones, heel stone etc
3) 2400-2200BC … central bluestone circle, the Avenue, Beaker burials
4) 2200-2000 … bluestone oval, outer bluestone circle
5) 2000-1600BC … Z holes, and later, the Y holes