Question: Which phase saw rearrangement of the bluestones?
About the article "Stonehenge", section "Stonehenge 3 IV (2280 BC to 1930 BC)".

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 3 IV (2280 BC to 1930 BC).
This phase saw further rearrangement of the bluestones.
They were arranged in a circle between the two rings of sarsens and in an oval at the centre of the inner ring.
Some archaeologists argue that some of these bluestones were from a second group brought from Wales.
All the stones formed well-spaced uprights without any of the linking lintels inferred in Stonehenge 3 III.
The Altar Stone may have been moved within the oval at this time and re-erected vertically.
Although this would seem the most impressive phase of work, Stonehenge 3 IV was rather shabbily built compared to its immediate predecessors, as the newly re-installed bluestones were not well-founded and began to fall over.
However, only minor changes were made after this phase.
The volume is split into four parts.
Part 1 deals with the geography and history of Stonehenge, including previous work at the site, and the site in its modern setting.
Part 2, entitled "Stonehenge, the monument in its setting" tackles the Mesolithic and earlier Neolithic evidence from the site, and then moves on to describe the development of the monument, including the three major phases of development, and the post-Bronze Age use of the site.
Part 3 deals with the artefacts and ecofacts (environmental data), and Part 4 is the discussion section.
The analysis showed that Atkinson's phasing of the monument no longer held, and a new scheme was set out: Phase 1, c.2950-2900 BC *Construction of ditch, inner bank, outer counterscarp bank *Construction of Aubrey Holes (interpreted as a ring of posts) *Primary fill accumulated in the ditch, and an organic layer over it Phase 2, c.2900-2400 BC *Secondary ditch fill accumulated, including some deliberate backfill *Post settings within the earthwork from the centre towards the southern entrance; also in the northeast entrance *Towards the end of the phase, cremations put in the partially filled Aubrey Holes and the upper ditch, and on and just inside the inner bank Phase 3, c.2550-1600 BC *3i: Bluestones set up in the Q and R Holes and then dismantled *3ii: Construction of the sarsen circle and the trilithons.
Possibly coeval with 3iii *3iii: Construction of another bluestone setting which included bluestone trilithons.
Possibly coeval with 3ii *3iv: Rearranged bluestones then set in a circle and oval *3v: The oval later rearranged to form a bluestone horseshoe *3vi: Digging of Y and Z Holes to take stones (presumed bluestones) but these were left unfilled The Avenue was also constructed during Phase 3. 
Bringing Back the Bluestones is a stage play by Derek Webb about a group from Pembrokeshire, called CarregLas, campaigning to have the Stonehenge bluestones returned to Wales. 
Main article: Claisen rearrangementDiscovered in 1912 by Rainer Ludwig Claisen, the Claisen rearrangement is the first recorded example of a rearrangement.
This rearrangement is a useful carbon-carbon bond-forming reaction.
An example of Claisen rearrangement is the [3,3 rearrangement of an allyl vinyl ether, which upon heating yields a γ,δ-unsaturated carbonyl.
The formation of a carbonyl group makes this reaction, unlike other sigmatropic rearrangements, inherently irreversible.  
 of Stonehenge.
The term "bluestone" in Britain is used in a loose sense to cover all of the "foreign" stones at Stonehenge.
It is a "convenience" label rather than a geological term, since at least 20 different rock types are represented.
One of the most common rocks in the assemblage is known as Preseli Spotted Dolerite—a chemically altered igneous rock containing spots or clusters of plagioclase feldspar.
It is a medium grained dark and heavy rock, harder than granite.
Preseli bluestone tools, such as axes, have been discovered all over the British Isles.
Many of them appear to have been made in or near Stonehenge, since there are petrographic similarities with some of the spotted dolerites there.
The bluestones at Stonehenge were placed there during the third phase of construction at Stonehenge around 2300 BC.
It is assumed that there were about 80 of them originally, but this has never been proven since only 43 remain.
The stones weigh between 2 and 4 tons each.
The majority of them are believed to have been brought from the Preseli Hills, about 250 miles away in Wales, either through glaciation (glacial erratic theory) or through humans organizing their transportation.
If a glacier transported the stones, then it must have been the Irish Sea Glacier.
In such event, one would expect to find other bluestones near the Stonehenge site, but no such bluestones have been found.
Recently the archaeological find of the Boscombe Bowmen has been cited in support of the human transport theory, while new glacier modelling supports the erratic theory.
Preseli Bluestone dolerite axe heads have been found around the Preseli Hills as well, indicating that there was a population who knew how to work with the stones.
A summary which outlines the major aspects of the Stonehenge "bluestone conundrum" has recently been published.
A new book devoted specifically to the problem of bluestone provenance and transport concludes that the Stonehenge bluestones are essentially an ill-sorted assemblage of glacial erratics.
Research into the origin of the bluestones is ongoing as of 2012.