  Using three newly identified galaxy clusters at z~1 (photometric redshift) we
measure the evolution of the galaxies within clusters from high redshift to the
present day by studying the growth of the red cluster sequence. The clusters
are located in the Spitzer Infrared Array Camera (IRAC) Dark Field, an
extremely deep mid-infrared survey near the north ecliptic pole with photometry
in 18 total bands from X-ray through far-IR. Two of the candidate clusters are
additionally detected as extended emission in matching Chandra data in the
survey area allowing us to measure their masses to be M_{500}= 6.2 \pm 1.0
\times 10^{13} and 3.6 \pm 1.1 \times 10^{13} solar masses. For all three
clusters we create a composite color magnitude diagram in rest-frame B-K using
our deep HST and Spitzer imaging. By comparing the fraction of low luminosity
member galaxies on the composite red sequence with the corresponding population
in local clusters at z=0.1 taken from the COSMOS survey, we examine the effect
of a galaxy's mass on its evolution. We find a deficit of faint galaxies on the
red sequence in our z~1 clusters which implies that more massive galaxies have
evolved in clusters faster than less massive galaxies, and that the less
massive galaxies are still forming stars in clusters such that they have not
yet settled onto the red sequence.
