On May 22, 1915, at about 4:00 p.m., Lassen Peak produced a violent explosive eruption that ejected rock and pumice and formed a larger and deeper crater at its summit. Within 30 minutes, volcanic ash and gas formed a column that reached altitudes of more than 30,000 feet (9,100 m) and could be seen from the city of Eureka, 150 miles (240 km) to the west. This column underwent a partial collapse, generating a pyroclastic flow composed of hot ash, pumice, rock, and gas that destroyed 3 square miles (7.8 km2) of land and spawned a lahar extending 15 miles (24 km) from the volcano and again reaching Hat Creek Valley.[69] Smaller mudflows also formed on every side of the volcano, as well a layer of pumice and volcanic ash that reached as far as 25 miles (40 km) northeast; volcanic ash was detected up to 280 miles (450 km) east at the city of Elko, Nevada.[70] Additionally, the lava flow on the volcano's northeastern flank was removed by this eruption, but not the similar deposit on the western flank.[67]
The eruptive output volume totaled 0.007 cubic miles (0.029 km3), dwarfed by the 1980 eruption of Mount St. Helens, which had a volume of 0.24 cubic miles (1.0 km3). The region on the volcano's northeastern flank destroyed by the eruptions, 3 square miles (7.8 km2) in area, is now known as the Devastated Area, and it along with other deposits from the volcano has been altered by erosion and regrowth of vegetation,[70] though the vegetation in Devastated Area is sparse due to its siliceous (rich in silica), nutrient-deprived soil, which cannot sustain normal tree growth due to its lack of water retention.[71] Due to their small size and thin deposits, the 1915 eruptions will likely not be well-preserved geologically.[70]
After 1915, steam explosions continued for several years, indicating extremely hot rock beneath Lassen Peak's surface. In May 1917, an especially strong steam explosion formed the northern crater on Lassen Peak's summit,[70] with eruptions lasting two days and producing an ash cloud that extended 10,000 to 12,000 feet (3,000 to 3,700 m) into the sky. June saw 21 additional explosions reported, further transforming the crater and creating a new vent on Lassen Peak's northwestern summit. In June 1919, steam eruptions occurred, and similar activity was observed on April 8 and April 9 in 1920, followed by steam eruptions lasting 10–12 hours in October of the same year. During February 1921, white steam erupted from eastern fissures on the volcano.[35] In total, about 400 eruptions were observed between 1914 and 1921,[66] which were the last eruptions in the Cascades before the 1980 eruption of Mount St. Helens,[72] which was the only other volcanic eruption in the contiguous United States during the 20th century.[73]
--Wikipedia
Quincy, California, where I live, is less than fifty miles away from Mt. Lassen. If it ever blows again during my lifetime I’ll probably know it as happens. Although very unlikely to happen, what an experience that would be. Over my lifetime I’ve visited Lassen Volcanic National Park many times. It’s a wondrous place, sort of a mini-Yellowstone, and within a mere couple of hours driving time from here. In 2009 I finally got the chance to hike to the peak of Mt. Lassen.
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Plate tectonics, the movement and interaction of Earth’s ever-changing and fragmented lithosphere, more specifically our continental and oceanic crustal plates, is what brings us the beauty of mountains, the fascination of volcanic eruptions and lava flows, and the terror of earthquakes and tsunamis.
Without volcanoes and earthquakes though, we wouldn’t be here. In the long, long, long story of our planet’s evolution volcanoes have given us the very land and soil and water upon which terrestrial life depends. The great diversity of life on Earth that we experience every day is because our land masses have split apart and moved about time and again over the past three billion years or so.
Sciencing.com
Despite their reputation as destructive forces, volcanoes actually were critical to the development of life on Earth. Without volcanoes, most of Earth's water would still be trapped in the crust and mantle. Early volcanic eruptions led to the Earth's second atmosphere, which led to Earth's modern atmosphere. Besides water and air, volcanoes are responsible for land, another necessity for many life forms. Volcanoes may be devastating in the moment, but ultimately Earth's life would not be the same, if it existed at all, without volcanoes.
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Atmosphere
As the Earth's mass accumulated, the less dense gases trapped in the Earth began to rise to the surface. Volcanic eruptions carried gases and water out from the Earth's interior. Using today's eruptions as a model, scientists believe the atmosphere generated by those volcanoes consisted of water vapor, carbon monoxide, carbon dioxide, hydrochloric acid, methane, ammonia, nitrogen and sulfur gases. Evidence for that early atmosphere includes extensive banded iron formations. These rock formations do not occur in oxygen-rich environments like Earth's present atmosphere.
The increasingly thick atmosphere accumulated as the proto-Earth cooled. Eventually the atmosphere reached its maximum capacity to hold water and the rain started. The volcanoes kept erupting, the Earth kept cooling and the rain kept coming down. Eventually the water began to accumulate, forming the first ocean. That first ocean contained fresh water.
Beginnings of Life
Some of the oldest rocks on Earth, about 3.5 billion years old, contain fossils identified as bacterial. Slightly older rocks, about 3.8 billion years old, contain traces of organic compounds. In 1952, graduate student Stanley Miller set up an experiment to simulate the conditions in early Earth's oceans and atmosphere. Miller's sealed system contained water and inorganic compounds like those found in volcanic gases. He removed the oxygen and inserted electrodes to simulate the lightning that usually accompanies volcanic eruptions, due the atmospheric disruptions by the volcanic dust and gases. To simulate natural evaporation and condensation, Miller put his experimental brew through cycles of heating and cooling for a week, while passing electric sparks through the flask. After a week, Miller's sealed system contained amino acids, the building blocks of living materials.
When we think of earthquakes and tsunamis today we tend to not look past property destruction and loss of life. But earthquakes themselves are only a byproduct of plate tectonics. In essence, they are but the release of energy stored up when one (very slowly) moving piece of Earth’s fragmented crust gets jammed up against another and comes to a halt, continuously building up more and more stored energy, and then suddenly overcomes friction and moves in one relatively great big jump. It’s the plate tectonics underneath it all (ooh, did I just pun?) that we should be thinking of in terms of earthquakes and the evolution of life on Earth.
The Conversation
When Charles Darwin published his theory of evolution by natural selection in 1859, the world hadn’t even heard of plate tectonics. The notion that continents drifted on molten rock currents deep in the Earth’s mantle was unimaginable.
So it would have come as a shock to Darwin to think the movement of the Earth’s continental plates could have been a major driver of evolutionary change in all life.
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Plate tectonics and nutrient cycles
Nutrients in the oceans ultimately come from weathering and erosion of rocks on the continents. Weathering breaks down the minerals in the rocks and releases the nutrient trace elements, which nourish life. Thus when weathering and erosion rates increase for extended periods, more nutrients are supplied to the oceans.
In the long term of geological history, erosion rates rise dramatically during mountain building events caused by the gradual collision of tectonic plates.
Geologists have known since the 1960s that collisions of tectonic plates lead to the formation of huge mountain ranges. The Himalayas were formed when India, drifting northwards after splitting off from the supercontinent of Gondwana, slammed into Asia and pushed up the Tibetan Plateau. These collisions are called called orogenic events and their timing through Earth’s history is now well established.
Continued erosion eventually depletes the surface of nutrients, causing a drop in the ocean’s nutrients. This might have lead to extinction events in the seas.
This is the first time nutrient trace element curves have been developed that demonstrate the relationship between tectonic collisions and the generation of cycles of nutrients.
While the link between these nutrient cycles as drivers of evolution and factors in mass extinction events remains to be proven, it really makes us think about evolution in a broad sense. Plate tectonics and evolution both operate on the same time scale of millions of years, and it seems logical that they could be causally related.
Extinction is a dirty word, yes? Well, not necessarily. Without periodic extinction of major groups of species over the life history of Earth, other species (like us!) would have never been given the chance to evolve and flourish. Death, on a mass scale, is key to the coming about of new life forms. It may be uncomfortable to think about, but if the dinosaurs hadn’t gone extinct some 65 million years ago the mammals that survived and evolved eventually into primates (you know, like us!) wouldn’t have been able to do what they did. Ken Ham may disagree (no, I’m not linking to him), but would you like to have been coexisting with and competing against the likes of velociraptors and Titanoboa? I know I wouldn’t.
Titanoboa (/tiˌtɑːnoʊˈboʊə/) is an extinct genus of very large snakes that lived in what is now La Guajira in northeastern Colombia. They could grow up to 12.8 m (42 ft) long and reach a weight of 1,135 kg (2,500 lb).
This concludes Part 1 of Forces of Nature. Part 2, Atmospherics, will be electrifying, on fire, and just might blow you away. (Oh, stop it, Forrest). ;)>
Now It's Your Turn
What have you noted happening in your area or travels? Anything been shakin’ or eruptin’? (Nothing that dramatic, I hope.) As usual post your observations as well as their general location in the comments.
Thank you.
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