I was once asked by a student if there was any danger that the Missoula Floods might occur again... a reasonable question from the standpoint of a student initially trying to grasp the scale and destructive power of these events. From my perspective though, I had not even considered the possibility, because the floods clearly depended on a set of conditions that no longer exist. So it took me a moment to find an answer, and to frame it in such a way as to not sound dismissive. I responded, "None whatsoever. The floods were caused by the breach of a glacial dam, and that glacier and the ones associated with it no longer exist."
Despite the ease of dismissing the potential hazard, it's not the least bit foolish, as one thinks about the potential devastation if there was a recurrence, to be concerned. Had I been standing (or more likely, on a boat) at this same location, looking in the same direction as above, at the time of the flood that deposited these erratics, there would have been no land in the scene before the ridge on the horizon. Everything else we see in this photo would have been submerged in nearly freezing, turbid, and turbulent water. Much better to raise the question of a possible risk, and finding it easily dismissed, than to ignore a potential risk and discovering too late that it's all too real.