  Thin and Thick disk metallicities overlap, but alpha(Fe) relations differ;
there is also a hiatus in time before the first thin-disk stars, with a minimum
metallicity [Fe/H] = -0.6. Thus there are two `G-dwarf' problems. We fit
metallicity distribution functions (MDFs) for the two disks derived by Wyse &
Gilmore (1995) with analytical models (for O and Mg). The Thick disk fits a
simple inflow model with effective yield and final [Mg/H] about the same as for
the Thin Disk, excluding continuous mass loss from the former as a source of
prompt initial enrichment (PIE) for the latter. The Thin disk has a narrow MDF
fitted (rather poorly) with a closed model having PIE from some other source,
or more elegantly with a slow infall model similar to the `two-inflow' scenario
of Matteucci et al., but with a PIE and a severe break in the age-metallicity
relation. Implications for radio-active cosmochronology are investigated.
