The fact that timber from the face of the mountain is spread in relatively uniform fashion over the entire surface of the slide is interpreted to mean that there was little tumbling action—that the slide moved as a single, if shattered, mass. One important scientific controversy has emerged from the earthquake. It relates to the time relationship, or sequence between the initial shock, the tidal waves, or seiches, how fast the huge quantities of water which overtopped the dam moved down the valley, and whether these slugs of water had rushed through the canyon in time to reach the site of the slide before the mountain fell. The stretch of the Madison running through the canyon is fresh, fast water, but normally it takes up to two hours for an object to run the sparkling, seven-mile, trout-rich stretch from Hebgen Dam to the mouth of the canyon. The big surges of water—the seiches overtopping the dam—would make it a lot faster. There are two big, related questions. Could the big surges of water reach the point of the slide soon enough? And just how soon after the first shock did the mountain fall? [Illustration: Ruined building on the fault line.] For the first couple of days after the quake, the theory persisted that the slide must have happened quite some time after the first shock—as late as 5:00 A. M., according to some theorists. But, as the facts, and the testimony of folks trapped near the slide—the Osts, Fredericks, Smiths, and Mrs. Bennett—became available, it was apparent that the slide must have closely followed the initial shock. Even if you discount the disrupted time sense of people under stress—when a minute can seem like an hour, and vice versa—it’s difficult to imagine that more than 20 minutes elapsed between the first shock and the slide. According to one set of calculations, big waves could have swept from the dam to the slide site in 18 minutes or so. [Illustration: A man stands in the gap left by the earthquake-caused simple fault scarp. (U. S. Geological Survey)] [Illustration: Something slipped here! Before the quake caused the ground drop, creating this magnificent scarp, the ground surface shown here was continuous. (U. S. Forest Service)] [Illustration: Surface elevation after quake.] Hebgen Lake Hebgen Fault Red Canyon Fault Although the quake caused much settling of the earth packed against the downstream side of Hebgen Dam’s concrete core, the relatively slight displacement of the sod cover is interpreted to mean that all three tidal waves passed over the dam before this earth subsided and separated from the core. Thus the water would have begun its race down the valley before the heavy earth-settling shocks hit the dam area. Those who support the high-water-at-the-moment-of-the-slide theory point to the great volume of water damage way below the slide.