We present a two-dimensional, time independent, kinematic simulation of a g
ravel streambed that models impacts between clasts as elastic collisions wi
thout momentum transfer between discrete, circular disks. The prototype bed
forms that we seek to simulate are the "stone cells" observed in Harris Cr
eek, south central British Columbia. The basic algorithm causes simulated s
tones to cluster into longitudinal structures that resemble such gravel bed
forms as imbricate clusters and cluster bed forms. A modified algorithm in
corporating programming rules such as stone rotation, entrainment probabili
ty inversely proportional to stone size, and the shielding effects of neigh
bors causes simulated stones to cluster into structures that resemble trans
verse ribs. Trials incorporating the rotation rule, with or without additio
nal 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 m
ost control on the development of an extended surface structure.