  A quantitative theory, based on the Zeldovich approximation, to provide an
approximate description of the evolution of structure is presented. We give an
expression for the characteristic scale of superlarge-scale structure which can
also be applied to power spectra with a Harrison-Zeldovich asymptotic. The
evolution of the characteristic scale of large-scale structure is described
with an analytical expression. It corresponds to the mean separation of
filaments or chains of galaxies.
  We apply the theory to some simulations and show that the theoretically
defined characteristic scale for LSS does also correspond to the 'physical
measurement' of the mean separation of dark matter LSS elements. This supports
our claim for a new theory for the quantitative description of the formation
and evolution of large-scale structure in the universe.
