Though they might look static, glaciers are actually rivers of ice flowing with real power, albeit in slow motion. Sometimes they ripple over obstacles like standing waves in a rapid. Sometimes they crash together in dueling cascades. Deep in the rugged glacial wilderness south of Chakachamna Lake, about 90 miles west of Anchorage, I flew over this bowl of intersecting glaciers as the sun was setting on a mid-September day. These glaciers were all converging on each other, merging with a hint of arrested violence, topsy-turvy in every direction.