In their mode of propulsion they were like the nuées ardentes of Mount Pelée and the “sand flow” of the Valley of Ten Thousand Smokes, Alaska. So rapidly did they rush down the steep upper slopes of Mount Mazama that they did not begin to dump their loads until they entered the canyons below or passed on to gentler gradients. Indeed, near their source they probably eroded the surface over which they moved, as the glowing avalanches of Mount Pelée, Merapi, and Komagatake are known to have done.
Before generalizing further, it seems best to discuss the main characters of the flows.
Fig. 23. Map of pumice, drift, rock outcrops, and main glacial striae |
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