We present a two-dimensional, time independent, kinematic simulation of a gravel streambed that models impacts between clasts as elastic collisions without momentum transfer between discrete, circular disks. The prototype bed forms that we seek to simulate are the stone cells observed in Harris Creek, south central British Columbia. The basic algorithm causes simulated stones to cluster into longitudinal structures that resemble such gravel bed forms as imbricate clusters and cluster bed forms. A modified algorithm incorporating programming rules such as stone rotation, entrainment probability inversely proportional to stone size, and the shielding effects of neighbors causes simulated stones to cluster into structures that resemble transverse ribs. Trials incorporating the rotation rule, with or without additional rules, produce a cobble structure most similar to the prototype. Of all the parameters in the simulation, the number of stones seems to have the most control on the development of an extended surface structure. ¿ 1999 American Geophysical Union