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23 Eruption of Mount St. Helens
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In the course of the gigantic eruption of the Mount St. Helens volcano in the year 1980, within hours and days geological formations were created which correspond very closely to others which, up to now, were thought to have been formed in a process taking thousands to millions of years. The observations of Mount St. Helens illustrate the fact that the geological formations of our Earth could have been formed in a series of short catastrophic events.
Before the eruption in 1980, Mount St. Helens, located in north western USA, was approximately 400 m higher than it is today. As a result of the heat generated by the eruption, the snow in the area of the summit of the nearly 3,000 m high mountain, mingled with sediment and rock debris. The streams of mud and debris flowed down into the valley at speeds of up to 150 km/h and, within a short amount of time, eroded canyons up to 200 m deep in the solid rock.
Regarding other canyons in America, most geologists assume that they were slowly carved out by the water of rivers during very long periods of time (slow erosion). The eruption of Mount St. Helens proves, however, that such geological formations can develop in a very short amount of time.
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Eruption Mount St. Helens
As a result of the explosion, around a million tree trunks were hurled into the nearby Spirit Lake. New canyons and new river systems and lakes were created and the water level of Spirit Lake was raised by approximately 75 m (1).
After the eruption, the lake was covered with an immense mat of Douglas fir, noble fir, hemlock fir, silver fir, western red cedar and Alaska yellow cedar. Careful observations have shown that the trunks tend to float in an upright position with the roots downwards. In the course of time the trees sank and were deposited on the lakebed. Some of the trees embedded themselves upright on the lakebed.
If we were to find these trunks in fossilised form within rock strata, they would appear to us to be a naturally-growing forest. It would seem that a forest of noble firs was followed by a forest of hemlock firs and finally by a forest of Douglas firs. The buried forests in the Ruhr Coal Basin can be cited as an example from the historical past. At that time, many tons of cortex trees up to 12 m high during the Carboniferous period were completely buried in the mud (2).
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Mount St. Helens in 1980 and 2007
The formation of peat and coal:
The waves in Spirit Lake caused friction between the tree trunks. This caused the water-soaked bark pieces to break off from the trunks, gradually covering the lakebed. Thus, within a few years, a peat layer, consisting of up to twenty-five percent tree bark and being several centimetres thick, was created. Studies showed that this peat has a close structural relationship to brown coal. Perhaps in Spirit Lake we are witnessing the first stage of the formation of coal.
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