In order for a disk to transition from the protoplanetary to debris disk phase, its primordial gas and dust must somehow be cleared from the system.  We are very interested in exactly how this transition takes place, particularly since this is the time in the life of a disk when it is likely to be forming planets.  We have investigated this stage of evolution by making careful imaging studies of systems that seem to be at various stages of the clearing process.  We have resolved giant dust cavities in young disks, and have modeled gas and dust in two types of systems at older (~10 Myr) ages: those that retain a molecular gas disk despite evolved debris-like dust, and those that have apparently primordial dust properties but greatly reduced molecular gas masses.  Click the icons below to check out some relevant papers.