  We present the evolution of dust and molecular gas properties in a sample of
11 $z\sim0.03$ starburst to post-starburst (PSB) galaxies selected to span an
age sequence from ongoing starburst to 1 Gyr after the starburst ended. All
PSBs harbour significant molecular gas and dust reservoirs and residual star
formation, indicating that complete quenching of the starburst due to
exhaustion or expulsion of gas has not occurred during this timespan. As the
starburst ages, we observe a clear decrease in the star-formation efficiency,
molecular gas and SFR surface density, and effective dust temperature, from
levels coincident with starburst galaxies to those of normal star-forming
galaxies. These trends are consistent with a natural decrease in the SFR
following consumption of molecular gas by the starburst, and corresponding
decrease in the interstellar radiation field strength as the starburst ages.
The gas and dust contents of the PSBs are coincident with those of star-forming
galaxies and molecular gas-rich early-type galaxies, and are not consistent
with galaxies on the red-sequence. We find no evidence that the global gas
reservoir is expelled by stellar winds or AGN feedback. Our results show that
although a strong starburst in a low-redshift galaxy may cause the galaxy to
ultimately have a lower specific SFR and be of an earlier morphological type,
the galaxy will remain in the "green valley" for an extended time. Multiple
such episodes may be needed to complete migration of the galaxy from the blue-
to red-sequence.
