  We report the experimental discovery of propagating trains of localized
structures -- oscillons -- on top of Faraday waves in a vertically-vibrated
fluid layer confined in a thin annular cell. These structures emerge
spontaneously beyond a threshold driving level and coexist with the underlying
periodic pattern, which experiences a slow drift; their height significantly
surpassing that of the pattern. Appearing individually or in groups of trains,
they move in the same or opposite directions with velocities largely exceeding
Faraday waves' drift. These results on pattern formation in parametrically
driven systems raise an open question about the theoretical explanation of this
complex behavior.
