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By Dan McKenzie and W. J. Morgan. Nature 224, 125–133. The original paper develops plate-velocity constraints for the migration and kinematic stability of triple junctions.

W. J. Morgan contributed to the kinematics of plate tectonics. With Dan McKenzie, he analysed how the relative motions of three plates constrain the evolution of a triple junction.^[ref]

The physical issue is compatibility: three separately specified boundary motions must meet at one moving junction. This makes a plate reconstruction more restrictive than drawing plausible boundary lines independently and helps distinguish configurations that can persist from those requiring a change of geometry.