  In a hierarchical cosmogony present-day galaxies build up by continuous
merging of smaller structures. At a redshift of three the matter content of a
typical present-day galaxy is split into about ten individual protogalactic
clumps. Numerical simulations show that these protogalactic clumps have a
typical distance of about 100 kpc, are embedded in a sheet-like structure and
are often aligned along filaments. Artificial QSO spectra were generated from
hydrodynamical simulations of such regions of ongoing galaxy formation. The
metal and hydrogen absorption features in the artificial spectra closely
resemble observed systems over a wide range in HI column density. Detailed
predictions of the column density as a function of impact parameter to
protogalactic clumps are presented for HI,CII,CIV,SiIV,NV and OVI. The expected
correlations between column densities of different species and their role in
understanding the physical properties of the gas from which galaxies form are
briefly discussed. The model is able to explain both high-ionization
multi-component heavy-element absorbers and damped Lyman alpha systems as
groups of small protogalactic clumps.
