  We reconsider the study of the geometric transitions and brane/flux dualities
in various dimensions. We first give toric interpretations of the topology
changing transitions in the Calabi-Yau conifold and the $Spin(7)$ manifold. The
latter, for instance, can be viewed as three intersecting Calabi-Yau conifolds
according to $\cp^2$ toric graph. Orbifolds of such geometries are given in
terms of del Pezzo complex surfaces. Second we propose a four-dimensional
F-theory interpretation of type IIB geometric transitions on the Calabi-Yau
conifold. This gives a dual description of the M-theory flop in terms of toric
mirror symmetry. In two dimensions, we study the geometric transition in a
singular $Spin(7)$ manifold constructed as a cone on SU(3)/U(1). In particular,
we discuss brane/flux duality in such a compactification in both type IIA and
type IIB superstrings. These examples preserve one supercharge and so have
${\cal N}= 1/2$ supersymmetry in two dimensions. Then, an interpretation in
terms of F-theory is given.
