  We construct a duality cycle which provides a complete supergravity
description of geometric transitions in type II theories via a flop in
M-theory. This cycle connects the different supergravity descriptions before
and after the geometric transitions. Our construction reproduces many of the
known phenomena studied earlier in the literature and allows us to describe
some new and interesting aspects in a simple and elegant fashion. A precise
supergravity description of new torsional manifolds that appear on the type IIA
side with branes and fluxes and the corresponding geometric transition are
obtained. A local description of new G_2 manifolds that are circle fibrations
over non-Kahler manifolds is presented.
