Over the next three days the snow line rises higher as we descend the canyon. Tributaries join the Middle Fork and the river deepens and becomes easier to raft. We find wolf tracks as large as Lynn’s hand. One night we camp in a stand of reddish ponderosa pine and build a huge bonfire with driftwood hauled off the gravel beach. At our final camp, with the 3,000-foot-high cliffs of the Impassible Canyon tilting upward in rocky steps, Griffin and Drew accept that they are not going to see, let alone kill, a black bear. But with a box of ammo left, I figure something has to die, so I offer up my now-retired tele boards. I stand the spent skis up against a log and we take turns emptying clips into them in the gathering dusk.