  We study the nonlinear evolution of unstable flux compactifications, applying
numerical relativity techniques to solve the Einstein equations in $D$
dimensions coupled to a $q$-form field and positive cosmological constant. We
show that initially homogeneous flux compactifications are unstable to
dynamically forming warped compactifications. In some cases, we find that the
warping process can serve as a toy-model of slow-roll inflation, while in other
instances, we find solutions that eventually evolve to a singular state.
Analogous to dynamical black hole horizons, we use the geometric properties of
marginally trapped surfaces to characterize the lower dimensional vacua in the
inhomogeneous and dynamical settings we consider. We find that
lower-dimensional vacua with a lower expansion rate are dynamically favoured,
and in some cases find spacetimes that undergo a period of accelerated
expansion followed by contraction.
