It wasn’t until 1956 that the age of the Earth was accurately measured. The Precambrian era suddenly became much longer!
Initially all rock on Earth was igneous. The magma that cooled down on the surface is referred to as VOLCANIC. The magma which cooled down below the surface is referred to as PLUTONIC. It took a long time for a crust to form.
The pattern of present day volcanoes provides clues as to what happened next. The pattern of earthquakes was even more informative alerting researchers to the existence of lines of activity on the floors of the ocean.
There was a strong correlation between mountain building and volcanic activity. But there had to more to it than that. How were the mountains formed and how were the isolated island volcanoes to be explained?
An earthquake at 8:32:17 a.m. on Sunday, May 18, 1980, caused the entire weakened north face to slide away, creating the largest landslide ever recorded. This allowed the partly molten, high-pressure gas- and steam-rich rock in the volcano to suddenly explode northwards toward Spirit Lake in a hot mix of lava and pulverized older rock, overtaking the avalanching face. An eruption column rose 80,000 feet (24 km; 15 mi) into the atmosphere and deposited ash in 11 U.S. states and significant ash in two Canadian provinces. At the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles (80 km) to the southwest. Less severe outbursts continued into the next day, only to be followed by other large, but not as destructive, eruptions later that year. Thermal energy released during the eruption was equal to 26 megatons.
It is funny the effects volcanoes have on people….
So now on to hot spots. Just checking you are all awake!
The Giant’s Causeway
We finish with a quiz. This is the largest volcano in the solar system. Where is it? (clue earlier).
I don’t think I’m going to manage to visit this one…. (adventure before dementia)