  We present results from a spectroscopic study of the very low mass members of
the Southern open cluster Blanco 1 using the Gemini-N telescope. We obtained
intermediate resolution (R~4400) GMOS spectra for 15 cluster candidate members
with I~14-20 mag, and employed a series of membership criteria - proximity to
the cluster's sequence in an I/I-Ks color-magnitude diagram (CMD), kinematics
agreeing with the cluster systemic motion, magnetic activity as a youth
indicator - to classify 10 of these objects as probable cluster members. For
these objects, we searched for the presence of the Li I 6708 A feature to
identify the lithium depletion boundary (LDB) in Blanco 1. The I/I-Ks CMD shows
a clear mass segregation in the Li distribution along the cluster sequence;
namely, all higher mass stars are found to be Li-poor, while lower mass stars
are found to be Li-rich. The division between Li-poor and Li-rich (i.e., the
LDB) in Blanco 1 is found at I=$18.78 \pm 0.24$ and I-Ks=$3.05 \pm 0.10$. Using
current pre-main-sequence evolutionary models we determine an LDB age of $132
\pm 24$ Myr. Comparing our derived LDB age to upper-main-sequence isochrone
ages for Blanco 1, as well as for other open clusters with identified LDBs, we
find good chronometric consistency when using stellar evolution models that
incorporate a moderate degree of convective core overshoot.
