In the shadow of a super volcano
27/08/14 05:34
We like to think of the ground beneath our feet as solid. Here in the hills, there is a lot of very hard granite in the center of our little island of hills. Around that granite upthrust are sedimentary stones. If you dig anywhere around our home, you will run into lots of limestone. The pieces can be as big as three or four feet across and present a challenge when setting a fence post or laying a cable. In my neighbor’s back yard, there were a few huge pieces of rock so large that the gas company had to route their pipe around them and the people laying television cable tried for days unsuccessfully to dig a trench to bary their fiber optic cable. They eventually found another path as well.
If one looks at the story of our earth from the perspective of geological history, however, the land we experience as solid is actually in motion. The hills were once plains and the area arose under tremendous forces. Of course that was long ago - perhaps as much as 2 billion years ago. I am no geologist, but I imagine a boiling pool of magma deep beneath the surface of the earth with the hard rocks above cooling when exposed to the air. The core of the hills were at the top of the bubble and they hardened in place as the surface cooled and the hardened rock formed a very thick layer on top of the earth’s hot core.
The hills are dramatic because they are surrounded by prairies. We live on a little island in the midst of the prairie that offers a unique place of cool and shelter for its own little circles of animals.
It is easier to imagine the geology of the region when one visits Yellowstone National Park. Recently our daughter and son-in law made a visit to the park and brought back pictures that reminded me of the many times I have visited. I remember marveling at the colors of the various hot pools. The colors are mostly caused by different kinds of bacteria that are able to thrive in the warm temperatures. The heat of the water comes from the magma deep beneath the surface. There are fissures in the rocks that allow the water to descend close enough to the heat to turn into steam and rise under pressure to form geysers. I like the mud pots, where the water is cool enough to be liquid, but hot enough for bubbles of steam to rise from the bottom. The mud boils and bubbles like thick soup in a pot.
The changes in Yellowstone are a bit easier to see than in other places because they occur on a somewhat quicker timescale than in other places. Between 2004 and 2010 the ground beneath Yellowstone was rising at a fast pace for geology, sometimes at a rate of over 2 inches per year. That’s motion too slow to feel if you are standing on the ground, but enough to measure if you are a geologist. The rate of rising has slowed in recent years, but there is plenty of evidence that great forces continue to shape the park.
The uprise created a bit of a fervor among geologists and others and there has been a lot of talk and a lot of media attention to the possibility of a Yellowstone super eruption. National Geographic Magazine devoted an entire issue to the topic and there was also a National Geographic television special on the subject. I didn’t see the television program, but I read the article with interest and saved the issue of the magazine in part because of the gorgeous pictures.
In human terms, the times between eruptions of the Yellowstone volcano are very long. It has been 70,000 years since the most recent small eruption and over 600,000 years since the last super eruption. I’m not sure how volcanologists and geologists discover the evidence of the timing of eruptions, but if Yellowstone follows its pattern, there could be another super eruption sometime in the next 100,000 years give or take a few hundred thousand years.
In other words, prediction of the precise time of the eruption is not possible with the knowledge we currently have.
A super eruption would be dramatic, burying the hills in ash,altering the climate of the planet for decades, burying the hills in ash, and rearranging the geology of the entire region.
The biggest geological event of my lifetime was the Hebgen Lake earthquake that occurred in August of 1959. The side of a mountain slid into a river and created a new lake. More than 50 million tons of rock and dirt were moved in a matter of minutes. Cracks opened in the earth, A campground was buried. New steam vents formed and the rhythm of some of the existing geysers was altered. It was dramatic and there were deaths and injuries from the shaking. But in geological terms, it was a very minor event when compared with the potential for even more massive earthquakes and eruptions.
Here in the shadow of Yellowstone, life goes on as usual. In fact, life on the surface of Yellowstone is quite normal as well. Tourists come and go. Buffalo and Elk graze. Wolves howl and hunt the edges of the herds. Beaver chew down trees and build dams. And the prairie dogs burrow under the earth with no knowledge of the molten rock that lis miles beneath their tunnels.
Our lives take place in the flow of a history that is much grander and of much longer duration that the moments we occupy. Every once in a while we git a glimpse of the grandeur of the universe when we gaze into a starry night or a deep colored pool in the Yellowstone mountains. Scientists discover a bit wider perspective through their studies and share that perspective with the rest of us.
And life goes on. Ours is but a tiny piece of a much bigger story.
That little piece, however, is filled with meaning and significance. For from our tiny place ein the big stream of history we are able to peer out and get a small view of the big picture. In us the universe has a degree of self awareness.
I won’t, however, be losing any sleep over the next big Yellowstone eruption.
If one looks at the story of our earth from the perspective of geological history, however, the land we experience as solid is actually in motion. The hills were once plains and the area arose under tremendous forces. Of course that was long ago - perhaps as much as 2 billion years ago. I am no geologist, but I imagine a boiling pool of magma deep beneath the surface of the earth with the hard rocks above cooling when exposed to the air. The core of the hills were at the top of the bubble and they hardened in place as the surface cooled and the hardened rock formed a very thick layer on top of the earth’s hot core.
The hills are dramatic because they are surrounded by prairies. We live on a little island in the midst of the prairie that offers a unique place of cool and shelter for its own little circles of animals.
It is easier to imagine the geology of the region when one visits Yellowstone National Park. Recently our daughter and son-in law made a visit to the park and brought back pictures that reminded me of the many times I have visited. I remember marveling at the colors of the various hot pools. The colors are mostly caused by different kinds of bacteria that are able to thrive in the warm temperatures. The heat of the water comes from the magma deep beneath the surface. There are fissures in the rocks that allow the water to descend close enough to the heat to turn into steam and rise under pressure to form geysers. I like the mud pots, where the water is cool enough to be liquid, but hot enough for bubbles of steam to rise from the bottom. The mud boils and bubbles like thick soup in a pot.
The changes in Yellowstone are a bit easier to see than in other places because they occur on a somewhat quicker timescale than in other places. Between 2004 and 2010 the ground beneath Yellowstone was rising at a fast pace for geology, sometimes at a rate of over 2 inches per year. That’s motion too slow to feel if you are standing on the ground, but enough to measure if you are a geologist. The rate of rising has slowed in recent years, but there is plenty of evidence that great forces continue to shape the park.
The uprise created a bit of a fervor among geologists and others and there has been a lot of talk and a lot of media attention to the possibility of a Yellowstone super eruption. National Geographic Magazine devoted an entire issue to the topic and there was also a National Geographic television special on the subject. I didn’t see the television program, but I read the article with interest and saved the issue of the magazine in part because of the gorgeous pictures.
In human terms, the times between eruptions of the Yellowstone volcano are very long. It has been 70,000 years since the most recent small eruption and over 600,000 years since the last super eruption. I’m not sure how volcanologists and geologists discover the evidence of the timing of eruptions, but if Yellowstone follows its pattern, there could be another super eruption sometime in the next 100,000 years give or take a few hundred thousand years.
In other words, prediction of the precise time of the eruption is not possible with the knowledge we currently have.
A super eruption would be dramatic, burying the hills in ash,altering the climate of the planet for decades, burying the hills in ash, and rearranging the geology of the entire region.
The biggest geological event of my lifetime was the Hebgen Lake earthquake that occurred in August of 1959. The side of a mountain slid into a river and created a new lake. More than 50 million tons of rock and dirt were moved in a matter of minutes. Cracks opened in the earth, A campground was buried. New steam vents formed and the rhythm of some of the existing geysers was altered. It was dramatic and there were deaths and injuries from the shaking. But in geological terms, it was a very minor event when compared with the potential for even more massive earthquakes and eruptions.
Here in the shadow of Yellowstone, life goes on as usual. In fact, life on the surface of Yellowstone is quite normal as well. Tourists come and go. Buffalo and Elk graze. Wolves howl and hunt the edges of the herds. Beaver chew down trees and build dams. And the prairie dogs burrow under the earth with no knowledge of the molten rock that lis miles beneath their tunnels.
Our lives take place in the flow of a history that is much grander and of much longer duration that the moments we occupy. Every once in a while we git a glimpse of the grandeur of the universe when we gaze into a starry night or a deep colored pool in the Yellowstone mountains. Scientists discover a bit wider perspective through their studies and share that perspective with the rest of us.
And life goes on. Ours is but a tiny piece of a much bigger story.
That little piece, however, is filled with meaning and significance. For from our tiny place ein the big stream of history we are able to peer out and get a small view of the big picture. In us the universe has a degree of self awareness.
I won’t, however, be losing any sleep over the next big Yellowstone eruption.