A few minutes ago, at 1:51 p.m, a magnitude 5.9 earthquake rattled Northern Virginia between Richmond and Washington. That's no small potatoes. Five nine is enough to crack foundations, knock things off shelves, and cause spontaneous pants wetting among people who have never been in or close to an earthquake. On the West Coast, 5.9 would be something to talk about for a week, but not a big deal. For context, the Japanese earthquake this spring and the 1964 Alaska earthquakes were over one thousand times stronger than this one.
Not all earthquakes are created equal. The amount of death and destruction that one causes depend on many factors besides the Richter number. In many cases magnitude isn't even the most important factor. Earthquakes release different kinds of waves. A simplified way of looking at it is to think of them as vertical, horizontal, and compression waves. Once the waves get moving their destructiveness is strongly modified by geographical features like soil composition and coastlines. In Japan, the tsunami generated by the earthquake was hundreds of times more destructive than the shaking itself. Finally, and this might be most important in Virginia, building codes make a huge difference. The West Coast is young and most of our buildings were constructed under very strict codes that paid attention to the danger of earthquakes. In Virginia, no one expects an earthquake and many of the buildings in cities are older brick buildings (just about the worst place to be in an earthquake).
It's too soon to hear many details. I hope people are okay. I hope they learn the lesson that earthquakes can happen anywhere. I'm probably way too optimistic, but I hope some of our leaders will get the message that government regulations, like those building codes that limit tremor damage on the West Coast, can be a good thing. Proper regulations, properly enforced can save lives and save property (I'm not sure which is more important to our current leaders).
On Facebook, my Alaskan friends are already chiming in. I suppose you are a real West Coaster if your first reaction to an earthquake somewhere else is to check its Richter number and then snort, "Ha! You call that an earthquake? Let me tell you about earthquakes...."
Showing posts with label geology. Show all posts
Showing posts with label geology. Show all posts
Tuesday, August 23, 2011
Saturday, April 10, 2010
What is a supervolcano?
Supervolcano is not a meaningful geological term, it is a media term. What most of us think of as a "normal" volcanic eruption is caused by ash and lava being vented from a magma chamber, a miles wide bubble of molten rock that has risen through the crust to a point just a few miles below the surface. Because it is hot, the magma wants to expand. As it gets close to the surface, the magma is able to create cracks above it that allow some of the molten material to escape. The surface manifestation of these pressure valves are volcanos.
For the last decade or so the term Supervolcano has been popular for describing caldera collapses. These happen when the the entire surface above the magma chamber gives way at once. If a normal eruption is a pressure cooker letting off a little steam through a safety valve, a caldera collapse is a pressure cooker without a safety valve blowing its lid. These produce enormous amounts of ash and gas. They produce sudden cooling events around the world; if other conditions are right they can tip the Earth into an ice age. And, of course, they bury and kill lots of things downwind from the eruption, preserving lots of high quality fossils. Think "giant Pompeii". The key points here are that these are singular eruptions lasting only a few days and producing mostly ash.
Lately, supervolcano has been being used in the press to describe flood basalts. These come from a different type of event that is not a familiar type eruption and does not form a volcanic cone. Flood basalts form when molten rock comes to the surface through long cracks and flows across the land covering hundreds--even thousands--of square miles of land. The flows can last for years and new flows can appear in the same area repeatedly over millions of years, burying the land under thousands of feet of rock. The Columbia Plateau of Eastern Washington and Oregon is the result of over two hundred seperate flows that occured over about a seven million year period of time (the dating of the flows is extremely contentious). These do not produce very many fossils because lava flows slowly enough for most animals to simply walk away and most plants get burned up. Even so, there are some fossils produced under special conditions. The key points here are that these are very slow events that produce mostly rock.
I'm complaining about this distinction because of news articles like this:
The article does not make clear that they are talking about flood basalts and not caldera collapses until paragraph twelve.
It appears that "supervolcanoes" is being used by journalists, and scientists who talk to jouranlists, to mean "big ass volcanoish happenings." They have managed to take vague term and make it completely useless.
For the last decade or so the term Supervolcano has been popular for describing caldera collapses. These happen when the the entire surface above the magma chamber gives way at once. If a normal eruption is a pressure cooker letting off a little steam through a safety valve, a caldera collapse is a pressure cooker without a safety valve blowing its lid. These produce enormous amounts of ash and gas. They produce sudden cooling events around the world; if other conditions are right they can tip the Earth into an ice age. And, of course, they bury and kill lots of things downwind from the eruption, preserving lots of high quality fossils. Think "giant Pompeii". The key points here are that these are singular eruptions lasting only a few days and producing mostly ash.
Lately, supervolcano has been being used in the press to describe flood basalts. These come from a different type of event that is not a familiar type eruption and does not form a volcanic cone. Flood basalts form when molten rock comes to the surface through long cracks and flows across the land covering hundreds--even thousands--of square miles of land. The flows can last for years and new flows can appear in the same area repeatedly over millions of years, burying the land under thousands of feet of rock. The Columbia Plateau of Eastern Washington and Oregon is the result of over two hundred seperate flows that occured over about a seven million year period of time (the dating of the flows is extremely contentious). These do not produce very many fossils because lava flows slowly enough for most animals to simply walk away and most plants get burned up. Even so, there are some fossils produced under special conditions. The key points here are that these are very slow events that produce mostly rock.
I'm complaining about this distinction because of news articles like this:
Scientists Explore Origins of 'Supervolcanoes' on the Sea Floor: Ancient Goliaths Blamed for Multiple Mass Extinctions
"Supervolcanoes" have been blamed for multiple mass extinctions in Earth's history, but the cause of their massive eruptions is unknown.
Despite their global impact, the eruptions' origin and triggering mechanisms have remained unexplained. New data obtained during a recent Integrated Ocean Drilling Program (IODP) expedition in the Pacific Ocean may provide clues to unlocking this mystery.
The article does not make clear that they are talking about flood basalts and not caldera collapses until paragraph twelve.
It appears that "supervolcanoes" is being used by journalists, and scientists who talk to jouranlists, to mean "big ass volcanoish happenings." They have managed to take vague term and make it completely useless.
Friday, March 12, 2010
Mammoths, floods, and whatnot
Construction workers drilling holes for a new overpass on I-5 near Ridgefield, Washington brought up pieces of mammoth ivory this January. Brad Clark, a Washington Transportation Department inspector, collected the pieces that, when reassembled, formed about four feet of the tip of a mammoth tusk. Mammoth ivory in Washington is nowhere near as common as in Alaska or northern Siberia, but it is not rare either. For that reason, the construction is going ahead without any attempt being made to see if there are more remains to be found. Even without digging up the rest of the remains, this tusk makes a departure point for for some nice educational stories.
The tusk.
The mammoth in question is almost certainly a Columbian mammoth (Mammuthus columbi) and not a woolly mammoth (M. primigenius). Columbian mammoths evolved earlier than woollies and emigrated to North America sooner. The simple version of their family tree shows them both as descendants of a common ancestor, the southern mammoth (M. meridionalis), which spread across Eurasia about four million years ago. One group of these mammoths, usually called the imperial mammoth (M. imperator) crossed into North America via the Bering land bridge at the beginning of the ice ages (c. 1.9 mya). The Columbians evolved from the imperials*. Back in Eurasia, the woollies evolved from the main group of southern mammoths. About 500,000 years ago, the woollies emigrated into North America. Both kinds of mammoths went extinct around the same time.
In North America, the two types of mammoths lived in different ecological zones and physical regions. The woollies stayed in northern grasslands close to the ice cap and the Columbians lived in a variety of different zones from the edge of the tundra all the way down to the edge of the tropical rainforests in Central America. So far, no woollies have been found west of the Rocky Mountains. The Ridgefield fragments have been sent to the Burke Museum here in Seattle, where Bax Barton will make a final identification of the species. Some mastodons have been found in the Pacific Northwest, so it is possible that the ivory is not from a mammoth at all. What would be frustrating would be if the ivory turns out to belong to a woolly. That would make the find important enough to warrant further investigation, but an administrative nightmare since the decision has already been made to continue working on the highway, which is the main north-south artery on the West Coast.
It is unlikely that this mammoth has any great scientific significance. However, if we could know its personal history, we would see that the mammoth's last hours witnessed to one of the most dramatic moments in northwestern geological history. The Oregonian article mentions it rather simply at the end of the article, "The tusk was buried about 30 feet deep in sediments piled up during the Missoula floods." I've written about these floods before.
During the last ice age, two ice sheets covered what is now Canada and extended into what is now the United States. The larger sheet, the Laurentian, was centered on Hudson Bay and, at its peak, extended almost to the Ohio River. The smaller ice sheet was a collection of mountain glaciers that grew together to form a single sheet. Geologists call this the Cordilleran Ice Sheet. It only extended to the US/Canada border region. At the end of the ice age, when the Laurentian and Fennoscanian (European) ice sheets began to melt, the changed global weather patterns caused the Cordilleran sheet to lurch south for a couple thousand years befor it too melted. Eastern Washington was just as conservative then as it is now. The local mammoths cited this change as proof that global warming was a hoax perpetrated by elitist ground sloths.
The western part of Montana, between the Continental Divide on the crest of the Rockies and the Idaho state line on the crest of the Bitterroot Mountains--an area about the size of West Virginia--is drained by the Clark Fork River. Unlike most rivers in the United States, the Clark Fork flows north. It loops across the Idaho panhandle near the Canadian border and joins the Columbia River in the extreme northeastern corner of Washington. When the Cordilleran Ice Sheet lurched southward, a branch of the ice sheet called the Purcell Lobe pushed into Idaho near the location of the present day town of Sandpoint and blocked the Clark Fork. Behind the Purcell Lobe all of the drainage of the Clark Fork was damned up, eventually forming a Great Lake sized body of water we call Glacial Lake Missoula. When the lake was full, the future location of the town of Missoula was beneath a thousand feet of water.
Because ice is lighter than water, an ice dam needs to be about ten percent higher than the water behind it in order to be stable. If the water gets higher than that, it essentially floats the dam off its foundation. That happened to Glacial Lake Missoula when the water was almost two thousand feet deep at the dam. The collapse of the dam was catastophically sudden. The lake pressed against the base of the dam with a pressure of nine hundred pounds per square inch. It took no more than a crack for the lake to get under the dam and tear it to shreds. The collapse only took a few hours.
Five hundred cubic miles of water flooded across Eastern Washington tearing up everything in its way. Hundreds of square miles of top soils were scoured down to bedrock. Grass, trees, and animals were carried away. At the Wallula Gap, a narrows where the Columbia River becomes the border between Washington and Oregon, the entire flood was forced into the channel of the river. In the Columbia Gorge, where the river carves its way through Cascade mountains, the flood appeared as a brown wall of water, several hundred feet high, traveling fifty an hour, pushing gale force winds ahead of it. For a brief moment,the Columbia carried several times more water than all the rivers in the world combined.
"Age's End" © 2005 Stev H. Ominski.
The flood waters arrive in the Columbia Gorge east of Portland. The viewer is standing on Crown Point looking toward Beacon Rock. This is one of an ongoing series of paintings by Ominski.
At narrow spots in the river the flood waters backed up forming temporary lakes. Geologists call the lake behind the Wallula Gap Lake Lewis, after Mr. Clark's travelling companion. Another lake formed over the present day locations of Portland, Oregon and Vancouver, Washington. The water that blasted through the Columbia Gorge spread out over the basin where the two cities now sit. About thirty miles below Portland, the river narrows again near a tiny town called Kalama. The Kalama Gap is no where near as impressive as the Columbia Gorge or the Wallula Gap, but it was sufficient to force the flood waters to back up and form a lake. Lake Allison, named after the geologist who mapped it, was about four hundred feet deep over downtown Portland and filled the Willamette River valley a hundred miles southward to the outskirts of Eugene. Fans of the University of Oregon fighting Ducks will be happy to know that Corvallis, home of their arch-rivals, the Oregon State Beavers, was underwater.
Lake Allison and Ridgefield, WA. Source.
As the water pooled behind the Kalama Gap, some of the vast amount of debris that it carried began to settle. The topsoil of Eastern Washington filled the Willamette valley to produce fertile farmland. Melting bergs from the ice dam deposited rocks that had been encased in the ice. A large meteorite was dropped near West Linn. A mammoth settled to the bottom near Ridgefield.
Until the radiocarbon dates are back, it will be hard to say exactly when the mammoth met its doom. The problem is, there was more than one Lake Missoula flood. After the first flood, the Purcell Lobe glacier surged forward, once again damming the Clark Fork, forming a new Lake Missoula, that, about fifty years later, breached the dam. This process was repeated as many as forty times over a 2500 year period. As the ice age ended and the glaciers got smaller, each ice dam was lower than the one before and the flood, consequently, smaller than the one before. However, since the Ridgefield mammoth was found only a few feet above the current level of the Columbia River, it could have been deposited by any of the floods.
It's equally hard to say where the mammoth came from. It could have been grazing right under the dam in Idaho when the flood waters caught it. It could have been caught somewhere in Eastern Washington or along the Columbia Gorge. It might have been in the Willamette Valley and been carried to Ridgefield as the waters of lake Allison drained. Or it might have drowned and settled to earth on the same spot.
Was anyone there to see the floods and this mammoth's last days? The answer is a firm "maybe." From organic debris in the sediments laid down, the Lake Missoula floods have been dated to have happened from 15,000-13,000 years ago. Until recently, archaeologists had no undisputed evidence of people in North America before the Clovis culture that began around 13,000 years ago. The Clovis people are believed to have traveled down the center of the continent between the Laurentian and Cordilleran Ice Sheets. This would have put them in Colorado around the same time as the last floods. A fine collection of Clovis tools was discovered in Eastern Washington in 1987, proving they did make it into the Northwest, but neither that site nor the last flood have been dated exactly enough to indicate whether this group was around to witness the floods.
During the 2002, '03, and '04 excavation seasons a group of paleontologists and anthropologists recovered human coprolites (also known as old poop) from the Paisley Caves in south central Oregon. Radiocarbon dating placed the oldest of the coprolites at 14,300 years old and the youngest at 13,000. The dates make it possible for the poopers to have witnessed any of about thirty floods. The Paisley Caves are two hundred miles south of the Columbia River, so it is also possible that the poopers never made it that far north. So far, no human remains or artifacts have been found in the flood deposits. For now, whether or not there were human witnesses to the floods is an open question.
The poop. Source.
Finally, did the floods have anything to do with the extinction of the mammoths and other Quaternary megafauna? On this we can be more definite. No. The last floods happened a good thousand years before the generally accepted date for the North American extinctions. Most disputes about the extinction date put it more recently, not further back.
Columbian mammoths as visualized by the Czech illustrator Zdenek Burian.
One last educational note. It's only appropriate that the Ridgefield mammoth ended up on the Washington side of the river. The Columbian mammoth is the official state fossil of Washington. Over in Oregon, it is the dawn redwood (Metasequoia). Nebraska also claims the Columbian mammoth, but they claim all types of mammoths. If they can't settle on one type of mammoth, I'm not sure they deserve a state fossil at all.
* Not to be confused with Rock and Roll Hall of Fame inductee Little Anthony & The Imperials.
The mammoth in question is almost certainly a Columbian mammoth (Mammuthus columbi) and not a woolly mammoth (M. primigenius). Columbian mammoths evolved earlier than woollies and emigrated to North America sooner. The simple version of their family tree shows them both as descendants of a common ancestor, the southern mammoth (M. meridionalis), which spread across Eurasia about four million years ago. One group of these mammoths, usually called the imperial mammoth (M. imperator) crossed into North America via the Bering land bridge at the beginning of the ice ages (c. 1.9 mya). The Columbians evolved from the imperials*. Back in Eurasia, the woollies evolved from the main group of southern mammoths. About 500,000 years ago, the woollies emigrated into North America. Both kinds of mammoths went extinct around the same time.
In North America, the two types of mammoths lived in different ecological zones and physical regions. The woollies stayed in northern grasslands close to the ice cap and the Columbians lived in a variety of different zones from the edge of the tundra all the way down to the edge of the tropical rainforests in Central America. So far, no woollies have been found west of the Rocky Mountains. The Ridgefield fragments have been sent to the Burke Museum here in Seattle, where Bax Barton will make a final identification of the species. Some mastodons have been found in the Pacific Northwest, so it is possible that the ivory is not from a mammoth at all. What would be frustrating would be if the ivory turns out to belong to a woolly. That would make the find important enough to warrant further investigation, but an administrative nightmare since the decision has already been made to continue working on the highway, which is the main north-south artery on the West Coast.
It is unlikely that this mammoth has any great scientific significance. However, if we could know its personal history, we would see that the mammoth's last hours witnessed to one of the most dramatic moments in northwestern geological history. The Oregonian article mentions it rather simply at the end of the article, "The tusk was buried about 30 feet deep in sediments piled up during the Missoula floods." I've written about these floods before.
During the last ice age, two ice sheets covered what is now Canada and extended into what is now the United States. The larger sheet, the Laurentian, was centered on Hudson Bay and, at its peak, extended almost to the Ohio River. The smaller ice sheet was a collection of mountain glaciers that grew together to form a single sheet. Geologists call this the Cordilleran Ice Sheet. It only extended to the US/Canada border region. At the end of the ice age, when the Laurentian and Fennoscanian (European) ice sheets began to melt, the changed global weather patterns caused the Cordilleran sheet to lurch south for a couple thousand years befor it too melted. Eastern Washington was just as conservative then as it is now. The local mammoths cited this change as proof that global warming was a hoax perpetrated by elitist ground sloths.
The western part of Montana, between the Continental Divide on the crest of the Rockies and the Idaho state line on the crest of the Bitterroot Mountains--an area about the size of West Virginia--is drained by the Clark Fork River. Unlike most rivers in the United States, the Clark Fork flows north. It loops across the Idaho panhandle near the Canadian border and joins the Columbia River in the extreme northeastern corner of Washington. When the Cordilleran Ice Sheet lurched southward, a branch of the ice sheet called the Purcell Lobe pushed into Idaho near the location of the present day town of Sandpoint and blocked the Clark Fork. Behind the Purcell Lobe all of the drainage of the Clark Fork was damned up, eventually forming a Great Lake sized body of water we call Glacial Lake Missoula. When the lake was full, the future location of the town of Missoula was beneath a thousand feet of water.
Because ice is lighter than water, an ice dam needs to be about ten percent higher than the water behind it in order to be stable. If the water gets higher than that, it essentially floats the dam off its foundation. That happened to Glacial Lake Missoula when the water was almost two thousand feet deep at the dam. The collapse of the dam was catastophically sudden. The lake pressed against the base of the dam with a pressure of nine hundred pounds per square inch. It took no more than a crack for the lake to get under the dam and tear it to shreds. The collapse only took a few hours.
Five hundred cubic miles of water flooded across Eastern Washington tearing up everything in its way. Hundreds of square miles of top soils were scoured down to bedrock. Grass, trees, and animals were carried away. At the Wallula Gap, a narrows where the Columbia River becomes the border between Washington and Oregon, the entire flood was forced into the channel of the river. In the Columbia Gorge, where the river carves its way through Cascade mountains, the flood appeared as a brown wall of water, several hundred feet high, traveling fifty an hour, pushing gale force winds ahead of it. For a brief moment,the Columbia carried several times more water than all the rivers in the world combined.
The flood waters arrive in the Columbia Gorge east of Portland. The viewer is standing on Crown Point looking toward Beacon Rock. This is one of an ongoing series of paintings by Ominski.
At narrow spots in the river the flood waters backed up forming temporary lakes. Geologists call the lake behind the Wallula Gap Lake Lewis, after Mr. Clark's travelling companion. Another lake formed over the present day locations of Portland, Oregon and Vancouver, Washington. The water that blasted through the Columbia Gorge spread out over the basin where the two cities now sit. About thirty miles below Portland, the river narrows again near a tiny town called Kalama. The Kalama Gap is no where near as impressive as the Columbia Gorge or the Wallula Gap, but it was sufficient to force the flood waters to back up and form a lake. Lake Allison, named after the geologist who mapped it, was about four hundred feet deep over downtown Portland and filled the Willamette River valley a hundred miles southward to the outskirts of Eugene. Fans of the University of Oregon fighting Ducks will be happy to know that Corvallis, home of their arch-rivals, the Oregon State Beavers, was underwater.
As the water pooled behind the Kalama Gap, some of the vast amount of debris that it carried began to settle. The topsoil of Eastern Washington filled the Willamette valley to produce fertile farmland. Melting bergs from the ice dam deposited rocks that had been encased in the ice. A large meteorite was dropped near West Linn. A mammoth settled to the bottom near Ridgefield.
Until the radiocarbon dates are back, it will be hard to say exactly when the mammoth met its doom. The problem is, there was more than one Lake Missoula flood. After the first flood, the Purcell Lobe glacier surged forward, once again damming the Clark Fork, forming a new Lake Missoula, that, about fifty years later, breached the dam. This process was repeated as many as forty times over a 2500 year period. As the ice age ended and the glaciers got smaller, each ice dam was lower than the one before and the flood, consequently, smaller than the one before. However, since the Ridgefield mammoth was found only a few feet above the current level of the Columbia River, it could have been deposited by any of the floods.
It's equally hard to say where the mammoth came from. It could have been grazing right under the dam in Idaho when the flood waters caught it. It could have been caught somewhere in Eastern Washington or along the Columbia Gorge. It might have been in the Willamette Valley and been carried to Ridgefield as the waters of lake Allison drained. Or it might have drowned and settled to earth on the same spot.
Was anyone there to see the floods and this mammoth's last days? The answer is a firm "maybe." From organic debris in the sediments laid down, the Lake Missoula floods have been dated to have happened from 15,000-13,000 years ago. Until recently, archaeologists had no undisputed evidence of people in North America before the Clovis culture that began around 13,000 years ago. The Clovis people are believed to have traveled down the center of the continent between the Laurentian and Cordilleran Ice Sheets. This would have put them in Colorado around the same time as the last floods. A fine collection of Clovis tools was discovered in Eastern Washington in 1987, proving they did make it into the Northwest, but neither that site nor the last flood have been dated exactly enough to indicate whether this group was around to witness the floods.
During the 2002, '03, and '04 excavation seasons a group of paleontologists and anthropologists recovered human coprolites (also known as old poop) from the Paisley Caves in south central Oregon. Radiocarbon dating placed the oldest of the coprolites at 14,300 years old and the youngest at 13,000. The dates make it possible for the poopers to have witnessed any of about thirty floods. The Paisley Caves are two hundred miles south of the Columbia River, so it is also possible that the poopers never made it that far north. So far, no human remains or artifacts have been found in the flood deposits. For now, whether or not there were human witnesses to the floods is an open question.
Finally, did the floods have anything to do with the extinction of the mammoths and other Quaternary megafauna? On this we can be more definite. No. The last floods happened a good thousand years before the generally accepted date for the North American extinctions. Most disputes about the extinction date put it more recently, not further back.
One last educational note. It's only appropriate that the Ridgefield mammoth ended up on the Washington side of the river. The Columbian mammoth is the official state fossil of Washington. Over in Oregon, it is the dawn redwood (Metasequoia). Nebraska also claims the Columbian mammoth, but they claim all types of mammoths. If they can't settle on one type of mammoth, I'm not sure they deserve a state fossil at all.
* Not to be confused with Rock and Roll Hall of Fame inductee Little Anthony & The Imperials.
Tuesday, January 26, 2010
Historical sea level fluctuations
A new study from the University of Haifa suggests sea levels might have fluctuated during historical times far more than previously believed. Dr. Dorit Sivan, who supervised the research, writes that an investigation of underwater ruins along the coast of Israel show short term changes of the sea level of almost a meter during the last 2500 years. We are currently near the highest level.
So far, only a press release version of the study has been released. I'd like to see the complete study when it comes out because this short summary leaves me with more questions than answers. The press release only mentions sites along a short stretch of coast (about forty miles) in the eastern Mediterranean. Has Sivan compared these results to records from any other part of the world? Considering that the Jordan River/Dead Sea valley is a rift zone, how can they be sure that local tectonic activity isn't involved? Do temperature records, such as those obtained the Greenland ice cores of pollen found in lake bed strata, support their sequence? For that matter, what is the sequence? Inquiring minds need to know.
Cross posted at Mammoth Tales.
According to Dr. Sivan, the changing sea level can be attributed to three main causes: the global cause – the volume of water in the ocean, which mirrors the mass of ice sheets and is related to global warming or cooling; the regional cause – vertical movement of the earth's surface, which is usually related to the pressure placed on the surface by the ice; and the local cause – vertical tectonic activity. Seeing as Israel is not close to former ice caps and the tectonic activity along the Mediterranean coast is negligible over these periods, it can be concluded that drastic changes in Israel's sea levels are mainly related to changes in the volume of water.
So far, only a press release version of the study has been released. I'd like to see the complete study when it comes out because this short summary leaves me with more questions than answers. The press release only mentions sites along a short stretch of coast (about forty miles) in the eastern Mediterranean. Has Sivan compared these results to records from any other part of the world? Considering that the Jordan River/Dead Sea valley is a rift zone, how can they be sure that local tectonic activity isn't involved? Do temperature records, such as those obtained the Greenland ice cores of pollen found in lake bed strata, support their sequence? For that matter, what is the sequence? Inquiring minds need to know.
Cross posted at Mammoth Tales.
Friday, January 08, 2010
Bad, badder, and baddest science
Fox News may have just published what will prove to be the stupidest science article of the year. Several science bloggers have already written about this, but the article is so wrong it deserves attention by a wider audience. This is the opening of the offending, and unsigned, piece:
Except for the fact that there is a high incidence of lung cancer in Xuan Wei, everything about these sentences is wrong.
The anonymous Fox News writer was trying to summarize a recent paper about a cancer cluster in a small area of southern China. The authors of the paper have discovered that the low grade coal used for cooking and heating in Xuan Wei contains a much higher amount of silica than coal anywhere else in the world. Exposure to crystalline silica, which most commonly comes from cutting and grinding rock, causes inflammation and scaring in the lungs, a condition called silicosis.
The coal used domestically in Xuan Wei comes from three seams that were laid down in the late Permian. The uppermost seam, the one that was laid down closest to the time of the Siberian flood basalts and the End Permian extinction, contains the highest amount of small grain silica. The researchers found that the silica was added to the coal after if formed, probably carried in by groundwater. As a source for the silica, they point to a local layer of flood basalts, the Emeishan basalts, which were laid dawn about ten million years before the End Permian extinction. natural erosion of these basalts would have made the ground water high in silica. Later the eruption of the Siberian basalts would have added silica to the atmosphere, which, carried by water, would have added more silica to the already silica rich coal.
The paper is a great piece of detective work aimed at locating the source of an extremely tight cancer cluster. The women of Xuan Wei get lung cancer at a rate twenty times the Chinese average. However, the solution to the mystery has nothing to do with supervolcanoes and nothing to do with dinosaurs. The mystery of how those got into the story probably has more to do with a scientifically illiterate intern trying to tie a fairly dry scientific paper to two far more exciting and popular topics. Chris Rowan has traced the lede sentence, to a press release issued by the American Chemical Association, with one very significant change. This suggests the possibility that the Fox writer did not read beyond the release and maybe the paper's abstract. Sadly, most of the people who read the Fox article will never know just how wrong it is.
The tremendous volcanic eruption thought to be responsible for Earth's largest mass extinction — which killed more than 70 percent of plants and dinosaurs walking the planet 250 million years ago — is still taking lives today.
Scientists investigating the high incidence of lung cancer in China's Xuan Wei County in Yunnan Province conclude that the problem lies with the coal residents use to heat their homes. That coal was formed by the same 250-million-year-old giant volcanic eruption — termed a supervolcano — that was responsible for the extinction of the dinosaurs.
Except for the fact that there is a high incidence of lung cancer in Xuan Wei, everything about these sentences is wrong.
- The dinosaurs did not go extinct 250 million years ago; dinosaurs did not exist 250 million years ago. An extinction event did occur 250 million years ago. It is usually called the End Permian event. At that time, over ninety percent of all sea life went extinct, including the trilobites, and around seventy percent of all land species went extinct. Just as the extinction of the dinosaurs, 65 million years ago, cleared the field for mammals to evolve, the End Permian extinction cleared the field for dinosaurs to evolve.
- Volcanoes do not make coal. Period.
- The Permian was not ended by the eruption of a supervolcano. Supervolcano is the popular name for an extraordinarily large caldera collapse. These events pump enormous amounts of ash into the atmosphere. The land downwind from a collapse can be buried under hundreds of feet of ash, killing all life and probably causing some extinctions. Globally, the amount of ash that lingers at high altitudes is enough to cause a sudden drop in temperatures that continues for years. If the right background conditions are in place, it is enough to trigger an ice age.
- The volcanic event that coincided with the End Permian extinction was the deposit of flood basalts in what is now Siberia. Flood basalts are lakes of lava that are deposited by slow-motion eruptions through a series of fissures that form over a large area, rather than single vents like more familiar volcanoes. Flood basalts events that can last millions of years. The flatlands of Eastern Washington are a flood basalt deposit that took over six million years to form.
The anonymous Fox News writer was trying to summarize a recent paper about a cancer cluster in a small area of southern China. The authors of the paper have discovered that the low grade coal used for cooking and heating in Xuan Wei contains a much higher amount of silica than coal anywhere else in the world. Exposure to crystalline silica, which most commonly comes from cutting and grinding rock, causes inflammation and scaring in the lungs, a condition called silicosis.
The coal used domestically in Xuan Wei comes from three seams that were laid down in the late Permian. The uppermost seam, the one that was laid down closest to the time of the Siberian flood basalts and the End Permian extinction, contains the highest amount of small grain silica. The researchers found that the silica was added to the coal after if formed, probably carried in by groundwater. As a source for the silica, they point to a local layer of flood basalts, the Emeishan basalts, which were laid dawn about ten million years before the End Permian extinction. natural erosion of these basalts would have made the ground water high in silica. Later the eruption of the Siberian basalts would have added silica to the atmosphere, which, carried by water, would have added more silica to the already silica rich coal.
The paper is a great piece of detective work aimed at locating the source of an extremely tight cancer cluster. The women of Xuan Wei get lung cancer at a rate twenty times the Chinese average. However, the solution to the mystery has nothing to do with supervolcanoes and nothing to do with dinosaurs. The mystery of how those got into the story probably has more to do with a scientifically illiterate intern trying to tie a fairly dry scientific paper to two far more exciting and popular topics. Chris Rowan has traced the lede sentence, to a press release issued by the American Chemical Association, with one very significant change. This suggests the possibility that the Fox writer did not read beyond the release and maybe the paper's abstract. Sadly, most of the people who read the Fox article will never know just how wrong it is.
Thursday, August 27, 2009
One of our seas is missing
The Aral Sea (actually a lake) was a landlocked body of water in Central Asia. A half century ago, it was the world's fourth largest inland sea. It was fed by two rivers, the Syr Daria and the Amu Daria (the ancient Oxus). Beginning in 1959, the Soviet Union began a series of large irrigation projects aimed at increasing amount the amount of commercial crops, mostly cotton, grown in Kazakhstan, Uzbekistan, and Turkmenistan.
As less and less water reached the sea, it began to dry up. As the shoreline receded, fishing villages became landlocked. Soon, that ceased to be a problem as increasing salinity killed most of the fish in the sea. Dust blowing off the lake bed, carrying with it salt and various pollutants, has become a public health hazzard. With the loss of the moderating effect of a large body of water, the summers have been getting hotter and the winters colder in that part of Central Asia.
By 2000 the sea had separated into three, barely connected, parts. The larger, southern, part had divided into a shallow eastern lobe and a deeper western lobe. The northern part of the sea, which had always been somewhat seperate from the rest, was an independent lake. In 2005, Kazakhstan built a dam between the lake’s northern and southern parts to stop the loss of water from the north. While the northern lake has returned to a degree of health, this doomed the south. The eastern lobe completely dried up earlier this year. Ironically, the northern lobe, which was once called the Small Aral Sea, may soon be the only Aral Sea.
Last week
As less and less water reached the sea, it began to dry up. As the shoreline receded, fishing villages became landlocked. Soon, that ceased to be a problem as increasing salinity killed most of the fish in the sea. Dust blowing off the lake bed, carrying with it salt and various pollutants, has become a public health hazzard. With the loss of the moderating effect of a large body of water, the summers have been getting hotter and the winters colder in that part of Central Asia.
By 2000 the sea had separated into three, barely connected, parts. The larger, southern, part had divided into a shallow eastern lobe and a deeper western lobe. The northern part of the sea, which had always been somewhat seperate from the rest, was an independent lake. In 2005, Kazakhstan built a dam between the lake’s northern and southern parts to stop the loss of water from the north. While the northern lake has returned to a degree of health, this doomed the south. The eastern lobe completely dried up earlier this year. Ironically, the northern lobe, which was once called the Small Aral Sea, may soon be the only Aral Sea.
Sunday, December 14, 2008
The geologists' 100 things meme
This is one of those lists where you bold the things you've seen or done. I was surprised at how well I did (26 and a couple halves) considering I'm not a geologist and not especially well traveled. Fortunately, the northwest corner of North America is a very geologically rich territory. I could have done even better. When I was a kid, my family traveled through a few more places on the list and either didn't stop or had no idea what we were seeing. Chris Rowan, the main geology blogger over at ScienceBlogs got 38 and a couple halves.
1. See an erupting volcano. [I've seen Mts. Illiamna and Spurr in Alaska spew ash and smoke]
2. See a glacier. I've stomped around on several in Alaska and British Columbia]
3. See an active geyser See an active geyser such as those in Yellowstone, New Zealand or the type locality of Iceland. [Yellowstone several times as a kid]
4. Visit the Cretaceous/Tertiary (KT) Boundary.
5. Observe (from a safe distance) a river whose discharge is above bankful stage.
6. Explore a limestone cave. [Lewis and Clark Caverns in Montana]
7. Tour an open pit mine. [I visited the Berkeley Pit in Butte, Montana when it was still operating]
8. Explore a subsurface mine. [I've never been deep inside one, but I have nosed around the opening to some abandoned mines in Alaska, Idaho, and Montana]
9. See an ophiolite, such as the ophiolite complex in Oman or the Troodos complex on the Island Cyprus.
10. An anorthosite complex, such as those in Labrador, the Adirondacks, and Niger (there's some anorthosite in southern California too).
11. A slot canyon. Many of these amazing canyons are less than 3 feet wide and over 100 feet deep. [Tokkum Creek in Kootenay National Park, British Columbia]
12. Varves, whether you see the type section in Sweden or examples elsewhere.
13. An exfoliation dome, such as those in the Sierra Nevada.
14. A layered igneous intrusion, such as the Stillwater complex in Montana or the Skaergaard Complex in Eastern Greenland. [not sure if this counts. I went camping in the Stillwater as a kid, without knowing what it was]
15. Coastlines along the leading and trailing edge of a tectonic plate. [Only one side, so far]
16. A gingko tree, which is the lone survivor of an ancient group of softwoods that covered much of the Northern Hemisphere in the Mesozoic.
17. Living and fossilized stromatolites (Glacier National Park is a great place to see fossil stromatolites, while Shark Bay in Australia is the place to see living ones)
18. A field of glacial erratics. [Alaska, of course]
19. A caldera. [Yellowstone again]
20. A sand dune more than 200 feet high.
21. A fjord. [Southeastern Alaska and British Columbia]
22. A recently formed fault scarp. [we moved to Alaska a few years after the Good Friday earthquake of 1964 and there were two good fault scarps still visible in Anchorage]
23. A megabreccia.
24. An actively accreting river delta. [not a big one, but lots of little ones on Alaska]
25. A natural bridge.
26. A large sinkhole.
27. A glacial outwash plain [Alaska and Canadian Rockies.]
28. A sea stack. [Oregon and Washngton coasts]
29. A house-sized glacial erratic. [the biggest I've seen was about the sise of an old Buick]
30. An underground lake or river.
31. The continental divide. [many, many times]
32. Fluorescent and phosphorescent minerals.
33. Petrified trees. [no whole sections of trees, but I have some chunks of petrified wood that I collected as a kid]
34. Lava tubes. [in a couple places in sotheastern Idaho].
35. The Grand Canyon. All the way down. And back.
36. Meteor Crater, Arizona, also known as the Barringer Crater, to see an impact crater on a scale that is comprehensible.
37. The Great Barrier Reef, northeastern Australia, to see the largest coral reef in the world.
38. The Bay of Fundy, New Brunswick and Nova Scotia, Canada, to see the highest tides in the world (up to 16m). [Cook Inlet Alaska has the second highest tides, up to about 14m]
39. The Waterpocket Fold, Utah, to see well exposed folds on a massive scale.
40. The Banded Iron Formation, Michigan, to better appreciate the air you breathe.
41. The Snows of Kilimanjaro, Tanzania,
42. Lake Baikal, Siberia, to see the deepest lake in the world (1,620 m) with 20 percent of the Earth's fresh water.
43. Ayers Rock (known now by the Aboriginal name of Uluru), Australia. This inselberg of nearly vertical Precambrian strata is about 2.5 kilometers long and more than 350 meters high.
44. Devil's Tower, northeastern Wyoming, to see a classic example of columnar jointing.
45. The Alps. [I flew over them, they look a lot like the Canadian Rockies, but smaller]
46. Telescope Peak, in Death Valley National Park. From this spectacular summit you can look down onto the floor of Death Valley - 11,330 feet below.
47. The Li River, China, to see the fantastic tower karst that appears in much Chinese art.
48. The Dalmatian Coast of Croatia, to see the original Karst.
49. The Gorge of Bhagirathi, one of the sacred headwaters of the Ganges, in the Indian Himalayas, where the river flows from an ice tunnel beneath the Gangatori Glacier into a deep gorge.
50. The Goosenecks of the San Juan River, Utah, an impressive series of entrenched meanders.
51. Shiprock, New Mexico, to see a large volcanic neck.
52. Land's End, Cornwall, Great Britain, for fractured granites that have feldspar crystals bigger than your fist.
53. Tierra del Fuego, Chile and Argentina, to see the Straights of Magellan and the southernmost tip of South America.
54. Mount St. Helens, Washington, to see the results of recent explosive volcanism.
55. The Giant's Causeway and the Antrim Plateau, Northern Ireland, to see polygonally fractured basaltic flows.
56. The Great Rift Valley in Africa.
57. The Matterhorn, along the Swiss/Italian border, to see the classic "horn".
58. The Carolina Bays, along the Carolinian and Georgian coastal plain
59. The Mima Mounds near Olympia, Washington
60. Siccar Point, Berwickshire, Scotland, where James Hutton (the "father" of modern geology) observed the classic unconformity.
61. The moving rocks of Racetrack Playa in Death Valley
62. Yosemite Valley
63. Landscape Arch (or Delicate Arch) in Utah
64. The Burgess Shale in British Columbia. [This is one we drove past, when I was a kid, without knowing what was there]
65. The Channeled Scablands of central Washington
66. Bryce Canyon
67. Grand Prismatic Spring at Yellowstone
68. Monument Valley
69. The San Andreas fault
70. The dinosaur footprints in La Rioja, Spain
71. The volcanic landscapes of the Canary Islands
72. The Pyrenees Mountains
73. The Lime Caves at Karamea on the West Coast of New Zealand
74. Denali (an orogeny in progress)
75. A catastrophic mass wasting event.
76. The giant crossbeds visible at Zion National Park .
77. The black sand beaches in Hawaii (or the green sand-olivine beaches).
78. Barton Springs in Texas.
79. Hells Canyon in Idaho
80. The Black Canyon of the Gunnison in Colorado.
81. The Tunguska Impact site in Siberia.
82. Feel an earthquake with a magnitude greater than 5.0. [several in Alaska and one in Seattle]
83. Find dinosaur footprints in situ.
84. Find a trilobite (or a dinosaur bone or any other fossil).
85. Find gold, however small the flake. [gold panning was one my regular summer pastimes as a kid]
86. Find a meteorite fragment
87. Experience a volcanic ashfall.[Mts. St Augustine and Spurr in Anchorage]
88. Experience a sandstorm.
89. See a tsunami.
90. Witness a total solar eclipse. [only partials]
91. Witness a tornado firsthand (Important rules of this game).
92. Witness a meteor storm, a term used to describe a particularly intense (1000+ per minute) meteor shower
93. View Saturn and its moons through a respectable telescope.
94. See the Aurora borealis, otherwise known as the northern lights. [many times]
95. View a great naked-eye comet, an opportunity which occurs only a few times per century. [Hyahkutake in 1996]
96. See a lunar eclipse. [both full and partial]
97. View a distant galaxy through a large telescope
98. Experience a hurricane.
99. See noctilucent clouds. [maybe]
100. See the green flash.
If they're going list atmospheric phenomena, I think I should get credit for sundogs and solar halos.
1. See an erupting volcano. [I've seen Mts. Illiamna and Spurr in Alaska spew ash and smoke]
2. See a glacier. I've stomped around on several in Alaska and British Columbia]
3. See an active geyser See an active geyser such as those in Yellowstone, New Zealand or the type locality of Iceland. [Yellowstone several times as a kid]
4. Visit the Cretaceous/Tertiary (KT) Boundary.
5. Observe (from a safe distance) a river whose discharge is above bankful stage.
6. Explore a limestone cave. [Lewis and Clark Caverns in Montana]
7. Tour an open pit mine. [I visited the Berkeley Pit in Butte, Montana when it was still operating]
8. Explore a subsurface mine. [I've never been deep inside one, but I have nosed around the opening to some abandoned mines in Alaska, Idaho, and Montana]
9. See an ophiolite, such as the ophiolite complex in Oman or the Troodos complex on the Island Cyprus.
10. An anorthosite complex, such as those in Labrador, the Adirondacks, and Niger (there's some anorthosite in southern California too).
11. A slot canyon. Many of these amazing canyons are less than 3 feet wide and over 100 feet deep. [Tokkum Creek in Kootenay National Park, British Columbia]
12. Varves, whether you see the type section in Sweden or examples elsewhere.
13. An exfoliation dome, such as those in the Sierra Nevada.
14. A layered igneous intrusion, such as the Stillwater complex in Montana or the Skaergaard Complex in Eastern Greenland. [not sure if this counts. I went camping in the Stillwater as a kid, without knowing what it was]
15. Coastlines along the leading and trailing edge of a tectonic plate. [Only one side, so far]
16. A gingko tree, which is the lone survivor of an ancient group of softwoods that covered much of the Northern Hemisphere in the Mesozoic.
17. Living and fossilized stromatolites (Glacier National Park is a great place to see fossil stromatolites, while Shark Bay in Australia is the place to see living ones)
18. A field of glacial erratics. [Alaska, of course]
19. A caldera. [Yellowstone again]
20. A sand dune more than 200 feet high.
21. A fjord. [Southeastern Alaska and British Columbia]
22. A recently formed fault scarp. [we moved to Alaska a few years after the Good Friday earthquake of 1964 and there were two good fault scarps still visible in Anchorage]
23. A megabreccia.
24. An actively accreting river delta. [not a big one, but lots of little ones on Alaska]
25. A natural bridge.
26. A large sinkhole.
27. A glacial outwash plain [Alaska and Canadian Rockies.]
28. A sea stack. [Oregon and Washngton coasts]
29. A house-sized glacial erratic. [the biggest I've seen was about the sise of an old Buick]
30. An underground lake or river.
31. The continental divide. [many, many times]
32. Fluorescent and phosphorescent minerals.
33. Petrified trees. [no whole sections of trees, but I have some chunks of petrified wood that I collected as a kid]
34. Lava tubes. [in a couple places in sotheastern Idaho].
35. The Grand Canyon. All the way down. And back.
36. Meteor Crater, Arizona, also known as the Barringer Crater, to see an impact crater on a scale that is comprehensible.
37. The Great Barrier Reef, northeastern Australia, to see the largest coral reef in the world.
38. The Bay of Fundy, New Brunswick and Nova Scotia, Canada, to see the highest tides in the world (up to 16m). [Cook Inlet Alaska has the second highest tides, up to about 14m]
39. The Waterpocket Fold, Utah, to see well exposed folds on a massive scale.
40. The Banded Iron Formation, Michigan, to better appreciate the air you breathe.
41. The Snows of Kilimanjaro, Tanzania,
42. Lake Baikal, Siberia, to see the deepest lake in the world (1,620 m) with 20 percent of the Earth's fresh water.
43. Ayers Rock (known now by the Aboriginal name of Uluru), Australia. This inselberg of nearly vertical Precambrian strata is about 2.5 kilometers long and more than 350 meters high.
44. Devil's Tower, northeastern Wyoming, to see a classic example of columnar jointing.
45. The Alps. [I flew over them, they look a lot like the Canadian Rockies, but smaller]
46. Telescope Peak, in Death Valley National Park. From this spectacular summit you can look down onto the floor of Death Valley - 11,330 feet below.
47. The Li River, China, to see the fantastic tower karst that appears in much Chinese art.
48. The Dalmatian Coast of Croatia, to see the original Karst.
49. The Gorge of Bhagirathi, one of the sacred headwaters of the Ganges, in the Indian Himalayas, where the river flows from an ice tunnel beneath the Gangatori Glacier into a deep gorge.
50. The Goosenecks of the San Juan River, Utah, an impressive series of entrenched meanders.
51. Shiprock, New Mexico, to see a large volcanic neck.
52. Land's End, Cornwall, Great Britain, for fractured granites that have feldspar crystals bigger than your fist.
53. Tierra del Fuego, Chile and Argentina, to see the Straights of Magellan and the southernmost tip of South America.
54. Mount St. Helens, Washington, to see the results of recent explosive volcanism.
55. The Giant's Causeway and the Antrim Plateau, Northern Ireland, to see polygonally fractured basaltic flows.
56. The Great Rift Valley in Africa.
57. The Matterhorn, along the Swiss/Italian border, to see the classic "horn".
58. The Carolina Bays, along the Carolinian and Georgian coastal plain
59. The Mima Mounds near Olympia, Washington
60. Siccar Point, Berwickshire, Scotland, where James Hutton (the "father" of modern geology) observed the classic unconformity.
61. The moving rocks of Racetrack Playa in Death Valley
62. Yosemite Valley
63. Landscape Arch (or Delicate Arch) in Utah
64. The Burgess Shale in British Columbia. [This is one we drove past, when I was a kid, without knowing what was there]
65. The Channeled Scablands of central Washington
66. Bryce Canyon
67. Grand Prismatic Spring at Yellowstone
68. Monument Valley
69. The San Andreas fault
70. The dinosaur footprints in La Rioja, Spain
71. The volcanic landscapes of the Canary Islands
72. The Pyrenees Mountains
73. The Lime Caves at Karamea on the West Coast of New Zealand
74. Denali (an orogeny in progress)
75. A catastrophic mass wasting event.
76. The giant crossbeds visible at Zion National Park .
77. The black sand beaches in Hawaii (or the green sand-olivine beaches).
78. Barton Springs in Texas.
79. Hells Canyon in Idaho
80. The Black Canyon of the Gunnison in Colorado.
81. The Tunguska Impact site in Siberia.
82. Feel an earthquake with a magnitude greater than 5.0. [several in Alaska and one in Seattle]
83. Find dinosaur footprints in situ.
84. Find a trilobite (or a dinosaur bone or any other fossil).
85. Find gold, however small the flake. [gold panning was one my regular summer pastimes as a kid]
86. Find a meteorite fragment
87. Experience a volcanic ashfall.[Mts. St Augustine and Spurr in Anchorage]
88. Experience a sandstorm.
89. See a tsunami.
90. Witness a total solar eclipse. [only partials]
91. Witness a tornado firsthand (Important rules of this game).
92. Witness a meteor storm, a term used to describe a particularly intense (1000+ per minute) meteor shower
93. View Saturn and its moons through a respectable telescope.
94. See the Aurora borealis, otherwise known as the northern lights. [many times]
95. View a great naked-eye comet, an opportunity which occurs only a few times per century. [Hyahkutake in 1996]
96. See a lunar eclipse. [both full and partial]
97. View a distant galaxy through a large telescope
98. Experience a hurricane.
99. See noctilucent clouds. [maybe]
100. See the green flash.
If they're going list atmospheric phenomena, I think I should get credit for sundogs and solar halos.
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