On the Upper Blaeberry, Thompson constructs a rough log raft--safer than canoe, for it will neither sink nor upset--whipsawing two long logs over a dozen spruce rollers. A sapling tree for a pole, packs in a heap in the center on brush boughs to keep them free of damp, and down the Blaeberry whirls the explorer with his Indian guides. Here, the water is clearest crystal from the upland snows. There, it becomes milky with the silt of glaciers grinding over stone beds; and glimpses through the forests reveal the boundless ice fields. By October, snow begins to fall on the uplands. The hoary evergreens become heaped with drifts in huge mushrooms. The upper snow fields curl over the edges of lofty precipices in great cornices that break and fall with the boom of thunder, setting the avalanches roaring down the mountain flanks, sweeping the slopes clean of forests as if leveled by some giant trowel. Somewhere between Howse’s Pass and the Blaeberry, Thompson had wintered, following his old custom of making the explorations pay by having his men trap and hunt and trade with the Sarcees and Kootenay Indians as he traveled. Advancing in this slow way, it was June of 1807 before he had launched his raft on the Blaeberry. Spring thaw has set the torrents roaring. The river is a swollen flood that sweeps the voyageurs through the forests, past the glaciers, on down to a great river, which Thompson does not recognize but which is the Columbia just where it takes a great bend northward at the modern railway stations of Moberly and Golden.