  We present a millimeter wave study of a cluster of bipolar CO outflows
embedded in the western end of the Circinus molecular cloud complex, G317-4,
that is traced by very high optical extinction. For an assumed distance of 700
pc, the entire Circinus cloud is estimated to have a mass of about 5E4 solar
masses. The opaque western portion that was mapped in this study has a mass of
about 10E3 solar masses, contains a number of embedded infrared sources and
various compact 1.3 mm continuum sources, and has a remarkable filamentary
structure with numerous cavities which appears to be the fossil remnants of
past star formation activity. The profusion of outflows in this region are
disentangled and linked to driving IRAS sources. Thus, the mapped portion of
Circinus contains at least 10 CO emitting molecular outflows. Assuming that
star formation has continued at a steady rate for the last several hundred
thousand years, the Circinus cloud is expected to have produced dozens of young
stars. Their outflows have severely altered the structure and kinematics of
this cloud as evidenced by the multitude of prominent cavities and dust
filaments that outline their boundaries. This level of star formation activity
is consistent with the numerous post-outflow phase H-alpha emission line stars
that have been found in this region. The Circinus cloud complex is an
archetypical case where star formation activity may have profoundly affected
the structure of a molecular cloud, producing its strikingly filamentary and
cavitated appearance and providing further evidence that star formation may be
a self regulated process.
