  We have performed a deep spectroscopic survey of extremely red galaxies on
the GOODS-South field, using GMOS on Gemini South. We present here spectra and
redshifts for 16 ERGs at 0.87<z<2.02, to a limit K=20.2. The ERHs are a mixture
of spheroidals, mergers and spirals, with one AGN. For at least 10 of these
galaxies we observe [OII] emission lines. We perform an age-dating analysis by
fitting the spectra and 9-band photometry of the ERGs with models of passively
evolving stellar populations combined with a younger star-forming component.
The best-fitting ages for the old stellar components range from 0.6 to 4.5 Gyr,
with a mean 2.1 Gyr. Masses range from 3 to 20 times 10^10 solar masses. The
star-forming component typically forms a few per cent of the total mass, with
dust reddening averaging E(B-V)=0.35. Its timescale tends to be short for
mergers (<50 Myr) and longer (200-800 Myr) for spiral ERGs.
