In surface-channel sound propagation, a set of caustics is formed that significantly facilitates sound scattering by volume inhomogeneities, thereby creating reverberation and prereverberation sound fields. The prereverberation time is primarily governed by the width of scattering pattern, which depends on sound frequency and parameters of the inhomogeneities. Kinematic calculations are carried out for the prereverberation effects as functions of the distance, number of ray cycles, and width of the scattering pattern for highly anisotropic volume inhomogeneities. The calculated reverberation times well agree with those experimentally measured (tenths to hundreds of milliseconds at ranges of several hundreds of kilometers).