When Mt. St. Helens erupted, we saw how quickly hundreds of feet of geologic formations can form. Within days, several hundred feet of new layers were deposited. Many of these layers were created by catastrophic mud flows traveling at high velocities. Geologists were impressed with the fact that the layers were not jumbled masses of material, but very finely sorted layers. These fine layers were unexpected. They formed simultaneously as the result of flow patterns within the larger flow; as parts of the mud slurry moved more rapidly, or slowly, than adjacent parts. Could this explain other geologic formations as well?
Another lesson learned from the eruption of Mt. St. Helens is that it does not take as long to form certain landforms as we had previously thought. Badlands, such as those in Badlands National Park, consist of gullies and ridges thought to take millions of years to erode. But scientists observed steam blasts, erupting to the surface, from trapped water in the hot volcanic layers at Mt. St. Helens. These eruptions produced steam pits having the same erosional features as the Badlands. How long did it take? Less than a day!