For more information about Sandbox model for avalanches visit:

  http://ccdw.org/~cjj/sand/

This program is a demostration for the avalanche model system described in
the paper:

  Title		Cohesion-induced deepening transition of avalanches
  Author	Chun-Chung Chen
  Journal	Phys. Rev. E 66, 061304 (2002).
  URL		http://link.aps.org/abstract/PRE/v66/e061304

