Discontinuous (random-inhomogeneous) bed is considered in the framework of model of percolation layer, for which the conception of correlation length is introduced. We present The problem of computing the correlation length of the percolation layer of finite thickness, in which some dimensions are larger than the correlation length, the other ones – are less, the volume fraction of conductors is close to the percolation threshold. The comparison of model results with empirical data is given.
