On the Shape of the Tail of a Two Dimensional Sand Pile
  We study the shape of the tail of a heap of granular material. A simple theoretical argument shows that the tail adds a logarithmic correction to the slope given by the angle of repose. This expression is in good agreement with experiments. We present a cellular automaton that contains gravity, dissipation and surface roughness and its simulation also gives the predicted shape. 
J.J.Alonso and H.J.Herrmann (Laboratoire P.M.M.H., \'Ecole   Sup\'erieure de Physique et Chimie Industrielles, Paris)