The upper course of Shatford Creek, located west of Penticton, British Columbia, is a step-pool channel. This implies that hydraulic mean depth was about 0.4 m, which is the same as the size of the dominant, step-forming boulders. This implies that the channel ought to be able to move metre class boulders. These figures imply that the largest boulders in the channel should be poised for movement. In fact, the channel is stable.
Effective stresses remain below the threshold to move the large, structure-forming boulders.
The reluctance of the boulders to move is greatly increased by their imbricate structure. The stability of the channel is the consequence of the step structure formed by the largest stones present.