  We introduce a new quantity, the mass flux density of galaxies evolving from
the blue sequence to the red sequence. We propose a simple technique for
constraining this mass flux using the volume corrected number density in the
extinction-corrected UV-optical color magnitude distribution, the stellar age
indexes H-delta-a and D_n(4000), and a simple prescription for spectral
evolution using a quenched star formation history. We exploit the excellent
separation of red and blue sequences in the NUV-r band color-magnitude diagram.
The final value we measure, 0.033 M_sun yr^-1 Mpc^-3, is strictly speaking an
upper limit due to the possible contributions of bursting, composite, and
extincted galaxies. However, it compares favorably with estimates of the
average mass flux that we make based on the red luminosity function evolution
derived from the DEEPII and COMBO-17 surveys (Bell et al 2004; Faber et al.
2005), 0.034 M_sun yr^-1 Mpc^-3. We find that the blue sequence mass has
remained roughly constant since z=1 (mass flux 0.01 M_sun yr^-1 Mpc^-3) but the
average on-going star formation of 0.037$ M_sun yr^-1 Mpc^-3 over 0<z<1 is
balanced by mass flux off the blue sequence. We explore the nature of the
galaxies in the transition zone with particular attention to the frequency and
impact of AGNs. The AGN fraction peaks in the transition zone. We find
circumstantial, albeit weak evidence that the quench rates are higher in higher
luminosity AGNs.
