  We present a theoretical derivation of a rheology for dense granular flow,
based on the process of inelastic collapse of neighboring particles. This
collapse creates regions of correlated motion, which control the viscous
behavior of the flow on a large scale. The result is a rheology that obeys the
scaling form observed experimentally by Pouliquen and by the "G.D.R. Midi"
group author. We identify the nature of the constraints imposed by inelastic
collapse on the grain-scale motions in the flow; finally, we show using an
energy cascade argument that the inelastic collapse need not proceed to the
final endpoint in order for the correlations we have identified to build up.
