  According to a popular scenario supported by numerical models, the mass
assembly and growth of massive galaxies, in particular the Early-Type Galaxies
(ETGs), is, below a redshift of 1, mainly due to the accretion of multiple
gas--poor satellites. In order to get observational evidence of the role played
by minor dry mergers, we are obtaining extremely deep optical images of a
complete volume limited sample of nearby ETGs.
  These observations, done with the CFHT as part of the \AD, NGVS and MATLAS
projects, reach a stunning 28.5)29 mag.arcsec-2 surface brightness limit in the
g' band. They allow us to detect the relics of past collisions such as faint
stellar tidal tails as well as the very extended stellar halos which keep the
memory of the last episodes of galactic accretion.
  Images and preliminary results from this on-going survey are presented, in
particular a possible correlation between the fine structure index (which
parametrizes the amount of tidal perturbation) of the ETGs, their stellar mass,
effective radius and gas content.
