  We consider the roughening of small angle grain boundaries consisting of
arrays of dislocations and found two transitions, corresponding to fluctuations
of the dislocations along and perpendicular to the boundaries. The latter
contributes to a large scale fluctuation of the orientation of the crystal but
the former does not. The transition temperatures of these transitions are very
different, with the latter occuring at a much higher temperature. Order of
magnitude estimates of these temperatures are consistent with recent
experimental results from elasticity and X-ray measurements in solid $^4$He.
