During the Analysis of the bone bed, it became obvious that not only was there a vertical sequence in the emplacing of the groups of units, but that the groups were, for the most part, congregated into locally restricted piles of bone units, unit groups, and non-articulated bones, each more or less separated from other similar piles (Figs. 30I, 31I). Something of this sort had already been noted by Chubbuck in the pattern of the bone outcropping on the surface before the site was excavated, but its full significance was not realized until the bone piles in the undisturbed portions of the site had been discovered. The presence of such piles of bone units suggested not only that a definite pattern had been followed in cutting up the buffalo, but that a number of cooperating social units of some kind had been engaged, each group processing a number of animals and disposing of the rejectamenta as they finished each butchering unit, or that the group successively undertook the butchering of one lot of bison before moving on to the next.