Deep rumblings through the earth, echoings from crags and cañons through the communicative air, suddenly heralded the triumphant starting of an enormous slide. About three hundred feet up the heights, a broken end-on embankment of rocks and snow, it came coasting, dusting into view, plunging towards me. As a rock-ledge separated the two ravines above the junction, I felt secure, and I did not realize until too late that I was to coast down on the slide. Head-on, it rumbled heavily toward me with its mixed and crumbling front, making a most impressive riot of moving matter. Again and again the snowy monster smashed its shoulder into the impregnable farther wall. At last, one hundred feet high and twice as wide, came its impinging, crumbling front. At times the bottom caught and rolled under, leaving the overhanging front to cave and tumble forward with snowy splashes. This crumbling front was not all snow; occasionally an iceberg or a cargo of stones fell forward. With snow flying from it as from a gale-swept, snow-piled summit, this monster of half a million tons roared and thundered by in a sound-burst and reverberation of incomparable depth and resonance, to plunge into a deeper, steeper rock-walled gorge. It probably was moving thirty-five or forty miles an hour and was gaining in velocity every second. The noise of its passing suppressed the sounds of the slide that started in the gulch above me. Before I could realize it, this slide swept down, and the snow on which I was standing burst up with me into the air, struck and leaped the low ledge, rammed the rear end of the passing slide, and landed me, snowshoes down, on top of it. The top was unstable and dangerous; it lurched, burst up, curled under, yawned, and gave off hissing jets of snow powder; these and the plunging movements kept me desperately active, even with my broad snowshoes, to avoid being swallowed up, or overturned and smothered, or crushed in the chaotic, fissuring mass. As its speed increased, I now and then caught a glimpse, through flying, pelting snow-particles, of shooting rocks which burst explosively through the top. At timber-line the gorge walls abruptly ended and the channel curved swiftly to the left in a broad, shallow ravine. The momentum of this monster carried it out of the ravine and straight ahead over a rough, forested ridge.