  We present an in-depth case study of three molecular clouds associated with
the walls of the Galactic supershells GSH 287+04-17 and GSH 277+00+36. These
clouds have been identified in previous work as examples in which molecular gas
is either being formed or destroyed due to the influence of the shells.
12CO(J=1-0), 13CO(J=1-0) and C18O(J=1-0) mapping observations with the Mopra
telescope provide detailed information on the distribution and properties of
the molecular gas, enabling an improved discussion of its relationship to the
wider environment in which it resides. We find that massive star formation is
occurring in molecular gas likely formed in-situ in the shell wall, at a
Galactic altitude of ~200 pc. This second-generation star formation activity is
dominating its local environment; driving the expansion of a small HII region
which is blistering out of the atomic shell wall. We also find new
morphological evidence of disruption in two smaller entrained molecular clouds
thought to pre-date the shells. We suggest that at the present post-interaction
epoch, the lifetime of this surviving molecular material is no longer strongly
determined by the shells themselves.
