The December issue of Antiquity features an article by Tim Darvill, Pete Marshall, Mike Parker Pearson and Geoff Wainwright called “Stonehenge remodelled”. It’s designed to be the definitive summary of the current rethinking about the monument’s construction history. You can see an abstract here, though you need to subscribe to read the paper.
http://antiquity.ac.uk/ant/086/ant0861021.htm
There is a much fuller study published by English Heritage available online (though not currently live).
http://research.english-heritage.org.uk/report/?15075
Read more, including a summary of the dates and stages at Mike Pitts' blog
http://mikepitts.wordpress.com/2012/12/01/stonehenge-in-five-easy-stages-or-perhaps-six/
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