It’s May 8, 1980. At 8:32 a.m. an earthquake of magnitude 5.1 is happening at Mount Saint Hellens, Washington USA. This mount is a volcano and the earthquake generates an eruption.
The top of the mountain at 400 meters is blasted. A mix of debris (gas, mud, and snow) generates an avalanche. The hole that has formed in the blasted top is releasing the pressure inside the volcano. Water contained in blows up in a steam explosion. The power of this explosion is 10 megatons (more than the power of a nuclear bomb).
Experts have expected the explosion to happen upwards. Instead, it happens northwards. Debris avalanche run 10 miles away and displace the waters of the nearby Spirit Lake. A wave of more than 250m meters is generated from the lake, and the water comes back in the form of mudflows.
A mudflow, also known as mudslide or mud flow, is a form of mass wasting involving fast-moving flow of debris and dirt that has become liquified by the addition of water. Such flows can move at speeds ranging from 3 meters/minute to 5 meters/second.
Wikipedia
Six major rivers in the area are affected by the mudflows. Mudflows are also generated by melted snow.
Pyroclastic flows coming from the eruption, and multiple eruptions are releasing liquids and gases. Dense clouds of debris are moving from the top to the valley.
The landscape before the explosion is radically changed. The forest that surrounded the mountain was destroyed, and all trees fell down. Debris has deposited and formed more than 240 meters of rock layers. Where there was only sky, now you find a solid rock.
At the north fork of the Toutle River, if we go upstream, near the volcano, we can find a very interesting area. This is called the Little Grand Canyon. This area presents a cliff formed by erosion, where rock layers formed during the eruptions are shown.
This canyon has formed in three phases. During the first eruption, the avalanche of debris deposited a massive and fragmental deposit that formed the lower part of the cliff. This massive layer has been deposited during the afternoon of May 18.
Underneath the area of the canyon, there was a huge buried glacier. Due to the heat produced by the deposit, the ice of the glacier became steam and started reaming its way out to the surface. A big steam explosion occurred. So in the first week after the eruption, you could see a huge pit 300 meters wide, 600 meters long, and 30 meters high, left from the explosion.
June 19, at 9 pm, a new eruption occurred, and pyroclastic flow started coming from the volcano in the form of dense black clouds rich in deposits. The eruption ended at midnight, and a new 8 meters layer was formed in only 3 hours. The layer deposited, as can be observed in the canyon, is composed of many fine layers.
Debris from the pyroclastic flow deposited in the pit, and sat there until March 19, 1982. When a mudflow filled the pit. The mudflow overflowed and fell into the river, carving the canyon on its way.
Rheology is the science that studies mudflow movement and transformation. In order to understand how a mudflow can carve a canyon in one day, we must know that, when a mudflow starts, it is very hard to stop it. Mudflows are very powerful, and they can overcome barriers, carry away whole forests of trees, and destroy bridges and houses. A mudflow can just be stopped by friction and leave down its sediment or can lose its deposit and become a dilute flow. A dilute flow has only 5% of the deposit. A dilute flow is very powerful and it is able to dig in the solid rock. This is what happened in Mt. St. Helens, where the Little Grand Canyon was eroded in one day.
So the higher layer of the cliff of the canyon is deposited mud.
What can geology learn from Mount Saint Helens? First of all that we don’t need millions of years in order to form rock layers. We only need the right conditions and mud.
Second: what happened on a small scale in Mount St Helens, explains what happened on a large scale during the flood in the rest of the world. Geologic formations like the Grand Canyon in Colorado, have the same features we see in Mt St Helens. So it’s reasonable to think that similar conditions on a larger scale occurred and formed the Grand Canyon quickly and not in millions of years.
Third: geologists have always thought that canyons are formed by millions of years of erosion, instead, they are formed in days by the drainage of mud.
Once again we have evidence that Noah’s flood is the most reasonable explanation for rock layers and consequently fossils formation.
Resources
https://creation.com/lessons-from-mount-st-helens
https://answersingenesis.org/geology/mount-st-helens/mt-st-helens/