Ongoing eruptions eroded the thick sediment dumped at the base of the volcano, producing multiple channels and canyons.
One such channel was dubbed ‘Little Grand Canyon’ (figure 6), being about 1/40 Its side walls were up to 40 m (140 ft) high, its width up to 45 m (150 ft), and a small stream of water ran through it.
Its smoke and rumbling were warning that something big was building up.
Officials set up an exclusion zone around the volcano based on scientists’ ideas about how an eruption would occur.
The Mount St Helens eruption also demonstrated how canyons can be formed much faster and in a different manner than conventionally thought.The big surprise was that the sediment deposited in fine layers called laminae.You would expect a catastrophic, high speed ash flow to churn the fine particles and form a uniform, well-mixed deposit.When we see what the volcano did in such a short time, we can better appreciate how the catastrophe of Noah’s Flood formed the much larger geological features on planet Earth.For many years, geologist Dr Steven Austin researched the geological effects of the Mount St Helens eruption and its aftermath.Someone coming across that canyon could easily conclude that it was eroded slowly and gradually by the small creek now running through it, over many hundreds or thousands of years.