  We present numerical simulations to describe the nucleosynthesis and
evolution of pre-Galactic clouds in a model which is motivated by cold dark
matter simulations of hierarchical galaxy formation. We adopt a SN-induced
star-formation mechanism and follow the chemical enrichment and energy input by
Type II and Type Ia SNe. We utilize metallicity-dependent yields and include
finite stellar lifetimes. We derive the metallicity distribution functions, the
age-metallicity relation, and relative elemental abundances for a number of
alpha- and Fe-group elements. We find that the dispersion of the metallicity
distribution function of the outer halo is reproduced by contributions from
clouds with different initial conditions. Clouds with initial masses greater
than that of present globular clusters are found to survive the first 0.1 Gyr,
suggesting that such systems may have contributed to the formation of the first
stars, and could have been self-enriched. More massive clouds are only stable
when one assumes an initial mass function that is not biased towards massive
stars. The predicted relative abundances of some alpha- and Fe-group elements
show good agreement with the observed values down to metallicities below [Fe/H]
= -4 when the iron yields are reduced relative to stellar models. The observed
scatter is also reproduced for many elements including the observed bifurcation
in [alpha/Fe] for stars with low [Fe/H]. However, the predicted dispersion may
be too large for some alpha elements unless a limited range of progenitor
masses is assumed. The results suggest that the low-mass SNeII were absent at
the very low metallicities, and that the upper mass limit for the first stars
that contributed to nucleosynthesis may be < 40 solar masses.
