Dynamical topology change in M theory

We study the topology change in M theory compactifications on Calabi--Yau three-folds in the presence of G flux (the four form field strength). In particular, we discuss vacuum solutions in strongly coupled heterotic string theory in which the topology change is inevitable within a single space--time background. For rather generic choices of initial conditions, the field equations drive the Kaehler moduli outside the classical moduli space of a Calabi--Yau manifold. Consistency of the solution suggests that degenerate flop curves -- just as wrapped M theory fivebranes -- carry magnetic charges under the four form field strength