  We discuss the lift of certain D6-antiD6-brane systems to M-theory. These are
purely gravitational configurations with a bolt singularity. When reduced along
a trivial circle, and for large bolt radius, the bolt is related to a
non-supersymmetric orbifold type of singularity where some closed string
tachyons are expected in the twisted sectors. This is a kind of open-closed
string duality that relates open string tachyons on one side and localised
tachyons in the other. We consider the evolution of the system of branes from
M-theory point of view. This evolution gives rise to a brane-antibrane
annihilation on the brane side. On the gravity side, the evolution is related
to a reduction of the order of the orbifold and to a contraction of the bolt to
a nut or flat space if the system has non-vanishing or vanishing charge,
respectively. We also consider the inverse process of reducing a
non-supersymmetric orbifold to a D6-brane system. For $C^2/Z_N\times Z_M$, the
reduced system is a fractional D6-brane at an orbifold singularity $C/Z_M$.
