Before the circle was moved to make way for the M90 it was excavated. Four phases of activity were recognized.
Phase 1 Was a class 1 henge monument containing a concentric ring of nine pits and a cremation lay outside the entrance.
Phase 2 A small burial cairn with kerb of of stones surrounded by a ring of standing stones. This monument was almost completely destroyed by later phases.
Phase 3 A ring of eight standing standing stones, graded in height from SW to NE; recumbent stones lay between the three tallest monoliths on the south-west arc. At the centre was a possible ring cairn which was accompanied by cremated burials in pits.
Phase 4 The centre of the monument was used as a metal working workshop for smelting iron and casting bronze.
Information from
The excavation of a henge, stone circles and metal working area at Moncreiffe, Perthshire
Margaret E C Stewart with contributions by Joanna Close-Brooks, H McKerrell,and Lisbeth M Thorns.
Proceedings of the Society of Antiquities of Scotland, 115 1985