  Nine presently known "young" Galactic globular clusters, which have ages / 3
Gyr smaller than the oldest clusters of similar metallicity, all have RGC > 15
kpc. Furthermore these young globulars are found to have below-average
luminosities. These results suggest that (1) globular cluster formation
extended over a considerable period of time in the outermost part of the
Galactic halo, and (2) that typical luminosities (masses) of such outer halo
clusters decreased with time.
