Sioux Falls Scientists endorse How the Earth Was Made as it covers
the history of the planet Earth from its formation from dust
and molten rock to flourishing with human life.
How the Earth Was Made
How the Earth Was Made (2008) - 94 minutes
How the Earth Was Made at Amazon.com
From assailing meteorites to the beginning of life on Earth, travel through the tumultuous 4.5 billion year history of our planet.
From a seething ocean of radioactive, molten rock to a refuge for life as we know it, Earth has undergone a staggering series of cataclysmic transformations in its long and epic history. Assailed relentlessly for millions of years by meteorites, our once toxic and hostile planet has been covered in water and in ice, and seen the rise and sundering of continents, the creation of an atmosphere, and, ultimately, the beginning of life.
How the Earth Was Made plots the twisting course of Earth's amazing journey. Using groundbreaking special effects and traveling to remote locations where our planet still bears the scars of it's violent history, this compelling documentary tells a story of unimaginable timescales, world-shattering forces, radical climates, and mass extinctions.
The History Channel® journeys back in time to show the creation of Earth's land masses, the birth of the first complex creatures, and devastating extinctions - before speculating on the future when all life becomes extinct.
A Timeline of the Earth's History
- 4.5 Billion Years Ago
The earth is formed from the collision of countless meteors in the young solar system. The planet's surface is an ocean of molten rock.
- 4.4 Billion Years Ago
Due to gradual cooling, the surface of the Earth solidifies. Water begins to form on the surface.
- 4 Billion Years Ago
After millions of years of relentless rain, 90% of the Earth is covered by water.
- 3.5 Billion Years Ago
Granite is first formed. The continents begin to take shape.
- 2.5 Billion Years Ago
Stromatolites begin filling the atmosphere with oxygen. A quarter of the planet's surface is covered by land.
- 1.5 Billion Years Ago
Increased levels of oxygen make the seas and sky look blue.
- 1 Billion Years Ago
Rodinia, the first supercontinent, is formed by the collision of all the Earth's continents.
- 700 Million Years Ago
Ice covers the entire Earth, killing almost all life.
- 650 Million Years Ago
Volcanic eruptions begin to tear Rodinia apart. Ice begins to retreat towards the poles.
- 500 Million Years Ago
There is a dramatic increase in the number and complexity of life forms, known as the Cambrian explosion.
- 400 Million Years Ago
The development of the ozone layer frees life to leave the oceans.
- 300 Million Years Ago
The continents converge again to form the supercontinent Pangaea. Huge insects, amphibians, and early reptilians begin to live on land.
- 250 Million Years Ago
Huge volcanic eruptions cause the extinction of 95% of living species.
- 230 Million Years Ago
The first dinosaurs evolve.
- 180 Million Years Ago
Pangaea begins to break apart.
- 100 Million Years Ago
Dinosaurs dominate a world largely covered by lush, tropical landscapes.
- 65 Million Years Ago
An enormous meteor lands in Mexico. In combination with large-scale volcanic eruptions, this event creates a huge dust cloud that causes the dinosaurs and 70% of all species on Earth to become extinct.
- 55 Million Years Ago
"The Age of Mammals". The Earth's landscapes begin to take their current forms.
- 6 Million Years Ago
The Grand Canyon begins to be formed.
- 2 Million Years Ago
Ancestors of modern humans are first seen. The ice ages arrive.
- 10,000 Years Ago
The last ice sheets retreat to the poles. Human life flourishes.
- Billions of Years in the Future
When Earth's core finally cools, will all life on the planet end?
7-12-19 3 questions seismologists are asking after the California earthquakes
Tectonic activity may be shifting very slowly away from the San Andreas Fault. A week after two large earthquakes rattled southern California, scientists are scrambling to understand the sequence of events that led to the temblors and what it might tell us about future quakes. A magnitude 6.4 quake struck July 4 near Ridgecrest — about 194 kilometers northeast of Los Angeles — followed by a magnitude 7.1 quake in the same region on July 5. Both quakes occurred not along the famous San Andreas Fault but in a region of crisscrossing faults in the state’s high desert area, known as the Eastern California Shear Zone. The San Andreas Fault system, which stretches nearly 1,300 kilometers, generally takes center stage when it comes to California’s earthquake activity. That’s where, as the Pacific tectonic plate and the North American tectonic plate slowly grind past each other, sections of ground can lock together for a time, slowly building up strain until they suddenly release, producing powerful quakes. For the last few tens of millions of years, the San Andreas has been the primary origin of massive earthquakes in the region. Now overdue for a massive earthquake, based on historical precedent, many people fear it’s only a matter of time before the “Big One” strikes. But as the July 4 and July 5 quakes — and their many aftershocks — show, the San Andreas Fault system isn’t the only source of concern. The state is riddled with faults, says geophysicist Susan Hough of the U.S. Geological Survey in Pasadena, Calif. That’s because almost all of California is part of the general boundary between the plates. The Eastern California Shear Zone alone has been the source of several large quakes in the last few decades, including the magnitude 7.1 Hector Mine quake in 1999, the magnitude 6.7 Northridge quake in 1994 and the magnitude 7.3 Landers quake in 1992 (SN Online: 8/29/18).
1-11-19 Earth’s missing chapter
An international team of scientists thinks it has solved one of geology’s great mysteries: What happened to a massive, missing layer of Earth’s crust? The Great Unconformity—a gap in the geological record of anywhere from 250 million years to 1.2 billion years—can be observed at the Grand Canyon, where the rocky layers offer a window into Earth’s history. One strata is made up of sedimentary rocks from the Cambrian period, which started some 540 million years ago, and below is a layer of crystalline rock that formed about 1 billion years ago. The new study suggests the missing layer or layers vanished during a hypothesized period known as Snowball Earth, when most of the planet was covered in ice, reports NationalGeographic.com. Researchers believe that roaming glaciers ground up a 3-mile-deep layer of the crust. Using a chemical analysis of ancient zircons—hardy minerals that lock in the geochemical conditions of their environment during formation—the scientists concluded the resulting sediment was dumped into the oceans and then sucked into Earth’s mantle by moving tectonic plates. “Earth does a really good job at erasing the tracks of its past,” says study co-author Bill Bottke, of the Southwest Research Institute in Boulder.
8-29-18 Chasing quakes with machine learning
Scientists have used machine learning to calculate the pattern of aftershocks following an earthquake. Aftershocks are further quakes that follow the "main shock". They are by definition smaller, but sometimes not by much. This is the first time a machine learning method has been used to work out where they might happen. Researchers hope this and similar techniques will improve our understanding of earthquake behaviour. "If you think about making forecasts of earthquakes," says study co-author Prof Brendan Meade of Harvard University, "you want to do three things; you want to predict when they're going to be, you want to say something about how large they're going to be and about where they're going to be. "What we wanted to do is to tackle the last leg of this problem - that is where aftershocks are going to be." The team used a database of over 100,000 earthquakes and aftershocks, including Japan's 2011 earthquake, to train a neural network to recognise aftershock patterns. They then set it to predicting these patterns in other earthquakes it hadn't seen before. Neural networks are modelled on the processes and patterns of the human brain. So rather than putting data about the main earthquake through a set of calculations, which is how aftershocks are currently forecast, the network had the processing power to explore many possible pathways. It could determine which areas around the fault - a fracture in the Earth's crust along which earthquakes occur - were likely to experience at least one subsequent shaking event after a main shock. "The neural network just did better," says lead author Dr Phoebe DeVries, from the University of Connecticut.
7-6-18 Kilauea’s spectacular pyrotechnics show no signs of stopping
From lavanadoes to laze and vog, the ongoing eruption is a refresher in volcanic vocabulary. As the Hawaiian volcano’s latest outburst enters its third month, scientists are still watching Kilauea 24/7. Such constant monitoring not only provides danger warnings aimed at keeping those nearby safe, but it also offers remote viewers the rare opportunity to observe the evolution of an eruption in real time. As magma within Kilauea’s summit crater, called Halemaumau, continues to drain and move toward the lower east rift zone, the crater floor is becoming increasingly unstable. The U.S. Geological Service has observed frequent rockfalls into the crater since mid-May; each collapse triggers a small explosion. One of the largest explosions happened June 30, when a collapse-explosion cycle released energy equivalent to a magnitude 5.3 earthquake. While a “Whomp!” and a slow-rising cloud of volcanic gas and ash marked that collapse, the real pyrotechnics are happening along nearly two dozen fissures, vents through which lava erupts, in that lower east rift zone. Lava fountains spurting from two fissures, Nos. 8 and 22, are feeding most of the lava flows now pouring into the ocean. It’s hard not to stare slack-jawed at images of molten rock spurting into the air, of glowing, fast-moving rivers of lava rushing into the ocean, or of the tangles of wispy-sharp shards of glass known as Pele’s hair. Check out these highlights of Kilauea’s show and the science (and volcanic vocabulary) we’re learning from them.
6-25-18 This volcano revealed its unique ‘voice’ after an eruption
After a strong eruption in 2015, Ecuador’s Cotopaxi ‘rang like a bell’. Ecuador’s Cotopaxi volcano has a deep and distinct voice. Between late 2015 and early 2016, Cotopaxi repeated an unusual pattern of low-frequency sounds that researchers now say is linked to the unique geometry of the interior of its crater. Identifying the distinct “voiceprint” of various volcanoes could help scientists better anticipate changes within the craters, including those that foretell an eruption. Ecuadoran scientists installed a network of specialized microphones on the volcano’s flanks that can record very low frequency sounds, or infrasound. Two weeks after the volcano’s August 2015 eruption, the network recorded the unusual sound pattern — a strong, clear oscillation that tapers off through time. The sound curve resembles a screw, or “tornillo” in Spanish, scientists report online June 13 in Geophysical Research Letters. Cotopaxi repeated this tornillo pattern 37 times between September 2015 and April 2016. Each time, the signal lasted through a dozen or more oscillations, resonating much like a musical instrument, before dying away. “[Cotopaxi] rang like a bell for more than a minute,” says geophysicist Jeffrey Johnson at Boise State University in Idaho, who led the study.
6-18-18 How volcanoes work
Kilauea's dramatic eruption has shaken Hawaii's Big Island. Could other U.S. volcanoes blow? Here's everything you need to know:
- What's happening in Hawaii? Kilauea, one of the most active volcanoes in the world, is in the midst of the most destructive eruption in its recent history.
- Why is Kilauea erupting now? The volcano has been steadily oozing lava since 1983, and erupting off and on since it was born between 300,000 and 600,000 years ago.
- What other volcanoes are active? There are 169 potentially active volcanoes in the U.S., according the United States Geological Survey.
- Are they dangerous? Potentially. About 50 volcanoes located in six states — Hawaii, Alaska, California, Oregon, Washington, and Wyoming — are rated high priority or highest priority by the USGS for monitoring for possible eruptions.
- Why is that? They're more explosive. Oceanic plates are denser than continental plates, and create less gaseous magma when they melt.
- Can scientists predict eruptions? With the right tools, researchers can forecast the likelihood of an impending eruption — but only several days to several weeks before it happens.
- How volcanoes kill: Of the more than 278,000 people who have died in volcanic eruptions since 1500, fewer than 1,000 were killed by flowing lava.
6-6-18 Why are there so many devastating volcanic eruptions right now?
High-profile volcanic eruptions in Hawaii and Guatemala are grabbing the headlines, but geophysics isn't responsible for connecting the two disasters. First Hawaii, where the Kilauea volcano has been spewing lava and ash for more than a month. Then Guatemala, where the Volcan del Fuego volcano erupted with huge and lethal force on Sunday. But did one cause the other? At least 75 deaths have been confirmed in Guatemala and 200 remain missing, while at least 80 houses have been destroyed in Hawaii. Given the scenes of devastation, people could be forgiven for thinking that a chain reaction of catastrophic volcanic activity is upon us. But volcanologists say that the truth is more prosaic. Volcanoes happen all the time in unpopulated areas without us noticing, but when two highly devastating eruptions happen at once, we automatically clutch for a common cause. “For instance, who noticed there was one in Vanautu in April?” says Jess Johnson, a volcanologist at the University of East Anglia who recently spent two years studying Kilauea in Hawaii. “There are so many volcanoes in the world, and there’s always something happening.” Historic data on volcanic eruptions catalogued by the US Smithsonian Institution’s Global Volcanism Program show that the numbers of eruptions has been fairly constant since 2000, hovering between around 65 and 80 per year. There are also solid geological reasons why eruptions tend to be isolated events. “They are fairly local phenomena,” says Johnson. Eruptions happen when rock beneath a volcanic summit melts to form magma, but the cause of this melting is usually local in nature, within just tens of kilometres. In Guatemala, one tectonic plate sliding over another is to blame. In Hawaii, Kilauea erupted after the floor of a lava lake at the summit collapsed, draining the material into the plumbing beneath. Different places, different geology, different causes. “If erupting volcanoes are more than 100 kilometres apart, there’s no connection,” says Johnson.
6-5-18 Here’s a look at the world’s deadliest volcanoes — and the ways they kill
Scientists compiled a database of all recorded volcanic fatalities since 1500. Guatemala’s Fuego volcano erupted explosively on June 3, sending hot gas and rock racing downhill in what’s known as a pyroclastic flow. At least 69 people were killed. Emergency officials are trying to reach buried villages to assess the scope of the disaster, but Fuego is already the world's deadliest eruption of 2018. The tragedy offers a grim reminder of the many dangers posed by volcanic eruptions. While pyroclastic flows figure prominently in an exhaustive list published last year by British scientists, there are many other potential threats including toxic gas and lava flows. The scientists analyzed how nearly 280,000 people have died in eruptions, including about 62,600 deaths from indirect causes such as famine and disease in the aftermath, since the year 1500. Nearly half of the total number of direct deaths, or about 125,000, came from just seven eruptions. They include the 1883 eruption of Krakatau, in Indonesia, that swept away approximately 36,000 in a tsunami triggered by the eruption. The 1815 eruption of Tambora, also in Indonesia, killed an estimated 12,000 people right away. (Indonesia has more people living near active volcanoes than any other country.) Globally, there are around 1,500 active volcanoes, with about 800 million people living within 100 kilometers of one. The new database breaks out information on how far from each eruption people have died.
5-25-18 More lava flows reach the coast as volcano threatens Hawaii
Lava is entering the ocean off Hawaii from a third flow, marking the third week of a volcanic eruption that has opened up nearly two dozen vents. Lava is entering the ocean off Hawaii from a third flow, marking the third week of a volcanic eruption that has opened up nearly two dozen vents, destroyed buildings and sent plumes of ash many kilometres into the sky. Low lava fountains were erupting from a nearly continuous 3 kilometre portion of the series of fissures that have opened up in the ground, scientists said. The fountains were feeding lava flows in channels down to the coast. The most eastern channel split, creating three ocean entries on Wednesday. Since the eruption began on May 3, Hawaii County has ordered about 2,000 people to evacuate from Leilani Estates and surrounding neighbourhoods. Hawaii officials have said they may need to evacuate a thousand more people if lava crosses key roads and isolates communities in the mostly rural part of the island where Kilauea is erupting. A blocked highway would cut people off from the only route to shops, schools and hospitals.
5-21-18 The volcanic eruption on Hawaii is now making an acidic fog
As lava from Kilauea plunges into the Pacific Ocean, clouds of hot acidic steam are being blasted off – and the eruption shows no signs of slowing down. The Kilauea volcano that began erupting on 30 April is becoming increasingly hazardous to residents of Hawaii’s Big Island. It is now creating a haze of hot, acidic fog and blasting out clouds of ash – and there is no end in sight. On Sunday, the Hawaiian Volcano Observatory reported two large explosions of ash from the summit, following an initial large eruption last Thursday. “At any time, activity may again become more explosive, increasing the intensity of ash production and producing ballistic projectiles very near the vent,” the Observatory warned. “Communities downwind should be prepared for ashfall as long as this activity continues.” The volcano claimed its first casualty on Saturday. A man’s lower leg was shattered instantly by a projectile from one of the many lava fountains erupting along the East Rift Zone, which divides the summit from the Pacific Ocean. In a further development, a river of molten lava streaming down the East Rift Zone finally reached the Pacific on Sunday. There it released large clouds of hot, acidic steam containing hydrochloric acid, after mixing with sea water. “It’s very hazardous, and the production of this lava haze is quite unpredictable,” says Jessica Johnson at the University of East Anglia, UK, who spent two years in Hawaii studying Kilauea.
5-17-18 Hawaii Mount Kilauea: Explosive eruption at volcano
An explosive eruption at Hawaii’s Kilauea volcano has sent ash thousands of metres into the sky. The US Geological Survey said the eruption took place at 05:00 local time (15:00 GMT). Staff at the volcano observatory and the national park had been previously evacuated. Since a new zone of Mount Kilauea began erupting almost two weeks ago, lava has wrecked dozens of homes and forced hundreds of people to be evacuated. A red aviation code had already been issued - warning pilots to avoid the potentially damaging ash cloud. Kilauea is one of five active volcanoes on the island of Hawaii.
5-15-18 Hawaii’s erupting volcano may blast out ‘10-tonne cannonballs’
As Kilauea continues erupting, lava is mixing with water, creating steam that could trigger massive explosions and throw large rocks up to a kilometre away. Large boulders 2 metres across and weighing 10 tonnes could soon begin blasting out from Kilauea, the erupting volcano on Hawaii’s Big Island. But the biggest imminent threat to residents could arise if the volcano starts spewing ash to heights of 6000 metres or more. The conditions are similar to those when Kilauea last erupted in 1924, which showered the island in ash for several months. “That’s what I would guess will happen next,” said Don Swanson of the Hawaiian Volcano Observatory, in a press conference video issued on 9 May. Kilauea has been unusually active since late April. On 30 April, the floor of the lava lake at the volcano’s summit collapsed. The lava has been draining ever since. By 9 May, and following a 6.9-magnitude earthquake on 3 May, it had already plunged almost 300 metres into the vertical shaft below. The lava is now below the level of water-saturated rock at 600 metres above sea level. “Since the earthquake, the lava lake has dropped in a very steady manner, at 2.2 metres per hour,” said Swanson. Because the lava has sunk so low, water is now draining into the empty shaft that it previously occupied. The walls of the crater are red hot, so the water is instantly turning to steam, which is now bellowing in white clouds from the volcano summit.
5-15-18 The tides are getting stronger thanks to the shifting continents
The ocean tides are the strongest they have been for millions of years, and they will get stronger for several million years to come – because of the position of the continents. Right now ocean tides are big and the next few million years will see them becoming bigger. That’s because our scattered continents are surrounded by ocean basins that are just the right size to make really powerful tides. In contrast, whenever all Earth’s continents clump together into a single supercontinent, the tides go limp. For the last 3 billion years, Earth’s continents have been conducting a stately dance. Roughly every 400 to 500 million years they cluster together into one giant supercontinent, before fragmenting again. The last supercontinent was Pangaea, which existed from 335 to 175 million years ago. Mattias Green at Bangor University in the UK and his colleagues wondered if the position of Earth’s continents, and hence the sizes of the ocean basins, might affect the strength of tides. To find out, they studied predictions of how the continents will move over the next 250 million years, and modelled how those movements might affect the tides. A high tide is a bulge in the water, caused by the gravitational pull of the Moon. The biggest “mega-tides” occur when the width of an ocean basin is a multiple of the width of the tidal bulge. This creates “resonance”: the Moon’s pull reinforces the way the water naturally slops about in that particular ocean, leading to a higher tide. The team found that the current Atlantic basin has just entered a resonant phase.
5-8-18 How long will Kilauea’s eruption last?
A volcanologist tackles that and other burning questions about the Hawaii volcano. Cracks open in the ground. Lava creeps across roads, swallowing cars and homes. Fountains of molten rock shoot up to 70 meters high, catching treetops on fire. After a month of rumbling warning signs, Kilauea, Hawaii’s most active volcano, began a new phase of eruption last week. The volcano spewed clouds of steam and ash into the air on May 3, and lava gushed through several new rifts on the volcano’s eastern slope. Threatened by clouds of toxic sulfur dioxide–laden gas that also burst from the rifts, about 1,700 residents of a housing subdivision called Leilani Estates were forced to flee their homes, which sat directly in the path of the encroaching lava. The event marks the 62nd eruption episode along Kilauea’s eastern flank, which is really part of an ongoing volcanic eruption that started in 1983. The volcano is one of six that formed Hawaii’s Big Island over the past million years. Mauna Loa is the largest and most central; Kilauea, Mauna Kea, Hualalai and Kohala occupy the island’s edges. Mahukona is currently submerged. All six are shield volcanoes, with broad flanks composed of hardened lava flows. Kilauea’s activity has now shifted to its southwest flank, which continues to steam. No new rifts have opened since May 7, but the eruption may be far from over, says Victoria Avery, a volcanologist and associate program coordinator for the U.S. Geological Survey’s Volcano Hazards Program, based in Reston, Va.
5-8-18 Hawaii volcano is causing havoc and will spew lava for days
The Kilauea volcano is unlikely to erupt explosively, but it will probably keep pumping out devastating lava for many days to come. Waves of lava are threatening countless properties, roads and forests on Hawaii’s Big Island as the Kilauea volcano continues erupting. The lava is spraying up in fountains up to 70 metres high, and reaching temperatures of more than 1000°C. Already, 35 buildings have been destroyed, including 26 homes in and around the island’s Leilani Estates area in the Puna district. 1700 residents have been evacuated. Kilauea is one of the most active volcanoes in the world. It became more active after 30 April when the floor of a lava lake at the volcano’s summit collapsed. Lava was sent cascading down into the volcano’s plumbing. The collapse fuelled multiple earthquakes, including a magnitude-6.9 quake on 3 May, the island’s largest for 40 years. By Monday 12 large fissures had opened up along the East Rift Zone, which runs from Kilauea’s summit down through the Puna district, according to the US Geological Survey. The cracks are spewing toxic sulphur dioxide gas and molten lava. “The most likely scenario is more fissures, and more lava flow,” says Jessica Johnson, a volcanologist at the University of East Anglia, UK, who spent two years at the Hawaiian Volcano Observatory studying Kilauea. “There’s still a lot of lava and pressure being supplied, but there’s unlikely to be an explosion.”
5-5-18 Kilauea: Earthquakes follow eruptions from Hawaii volcano
A number of strong earthquakes have hit Hawaii's Big Island, a day after the eruption of the Kilauea volcano. One 6.9 magnitude quake, south-east of the volcano, was the most powerful to hit the US state since 1975. It briefly cut power and sent people fleeing from buildings but there was no tsunami warning. Meanwhile, several fresh eruptions spewed fountains of lava 30m (100ft), destroying several homes and leaving fissures on three streets. The Civil Defense Agency told any remaining residents to evacuate. It said there were deadly levels of dangerous sulphur dioxide gas in the air and emergency crews would not be able to help anyone affected. The new volcanic activity in Mt Kilauea's lower east rift zone amounted to "vigorous lava spattering", the US Geological Survey (USGS) said, adding that additional outbreaks in the area were likely. The lava was not travelling more than a "few tens of yards" from the vents, which were on streets in the Leilani Estates neighbourhood near Big Island's eastern tip, the USGS said. However, ground deformation was continuing and there was high earthquake activity in the area, it said. Meanwhile, the level of the lava lake inside the volcano was continuing to drop. Two homes were destroyed in the latest activity, ABC quoted Hawaii island Mayor Harry Kim as saying. Maija Stenback, an eyewitness, told the BBC the eruption "was like when someone plays the bass really heavy: you could really feel the power and the lava". "The colour was unbelievable, and the sound was unbelievable," she said. "You could hear and feel the eruption a good half a mile away, and the closer you got, the more you could feel it." Residents described fleeing their homes on Thursday evening. (Webmaster's comment: Building homes next to an active volcano may not be the wisest idea.)
5-4-18 Kilauea: Hawaii emergency declared over volcano eruption
Kilauea volcano has erupted near a residential area on Hawaii's largest island, prompting a local state of emergency and the mandatory evacuation of 1,700 residents. Streams of lava have been seen running through woods and bubbling on to roads. Extreme levels of dangerous sulphur dioxide gas have been detected in the area, the Civil Defense Agency said. Kilauea is one of the world's most active volcanoes and the eruption follows a series of recent earthquakes. "It sounds like a jet engine. It's going hard," resident Ikaika Marzo told the Honolulu Star-Advertiser. Community centres have been opened to provide shelter for evacuees. Officials had been warning residents all week they should be prepared to evacuate as an eruption would give little warning. A volcanic crater vent - known as Puu Oo - collapsed earlier this week, sending lava down the mountain's slopes towards populated areas. Talmadge Mango, the civil defence administrator for Hawaii County, told the BBC that power lines had melted off their poles in one area. "Seismic activity is still extremely high, so we feel that this might just be the beginning of things," he said.
1-29-18 Wave of massive volcanoes created Earth’s first supercontinent
2.2 billion years ago, a huge build-up of pressure inside the Earth triggered vast volcanic eruptions, which formed the first ever supercontinent. The world’s continents arrived in a blaze of fury. A pressure blow-out seems to have caused vast amounts of molten rock to spew out of the Earth and harden into solid land. Until about 2.2 billion years ago, Earth was mostly underwater. A few small landmasses existed, but nothing like the vast continents we have today. To understand how the continents formed, Christopher Spencer at Curtin University in Australia and his colleagues did the most comprehensive audit yet of the global geological record. They found something strange: almost no volcanic rocks formed between 2.3 and 2.2 billion years ago. “Plenty formed before and after, but hardly any formed during this time,” says Spencer. “It was like there was this dramatic shutdown.” At 2.2 billion years ago, the researchers found a sudden surge in the amount of land produced. They could tell because, when magma wells up from underground and crystallises, the resulting rock has giveaway chemical properties. The researchers believe powerful whirlpool currents in the mantle, deep inside the Earth, may have been responsible for the lull and flare-up in geological activity. Between 2.3 and 2.2 billion years ago, they think these currents pulled together any small chunks of land that existed. “Once they became stuck in the middle, all volcanic activity on these land fragments pretty much stopped,” says Spencer. Over time, heat built up under these static landmasses. Eventually, the enormous pressure sparked intense volcanic activity that spewed magma in all directions for millions of years.
10-27-17 A deadly 2014 landslide’s power came from soils weakened by past slides
A deadly 2014 landslide’s power came from soils weakened by past slides
The Washington mudflow moved almost like an earthworm, extending and contracting. Earth weakened by previous landslides and soils behaving like water were responsible for the unusual size of a deadly 2014 landslide, two scientists reported October 24 at the Geological Society of America’s annual meeting. Understanding why this landslide was so mobile could help geologists better map the hazards that could lead to others like it and prevent future loss of life. In March 2014, following more than a month of heavy rainfall, a wall of mud suddenly rushed down a hillside near Oso, Wash., engulfing houses and trees before spilling into the Stillaguamish River valley (SN: 4/19/14, p. 32). The debris flow killed 43 people and destroyed dozens of homes. The valley had seen landslides before, most recently in 2006. But the “run-out” — the size of the debris flow — of the Oso landslide was uncommonly large, spreading a fan of mud and debris across 1.4 kilometers. To unravel the sequence of events leading to the landslide, Brian Collins and Mark Reid, both with the U.S. Geological Survey in Menlo Park, Calif., first mapped the debris that made up the landslide, including large still-intact blocks of hillside called hummocks, glacial sediments and fallen trees. The researchers then used those maps to track where the different parts of the debris had originated and where they ended up. From that, the duo determined that sediments weakened and previously mobilized by the 2006 landslide failed first, followed by sediments that had failed in a prehistoric landslide and finally by intact sediments.
8-15-17 Seismologists get to the bottom of how deep Earth’s continents go
Seismologists get to the bottom of how deep Earth’s continents go
Analysis of seismic waves finds runny rock layer where landmass ends. Earthquake vibrations are revealing just how deep the continents beneath our feet go. Researchers analyzed seismic waves from earthquakes that have rocked various regions throughout the world, including the Americas, Antarctica and Africa. In almost every place, patterns in these waves indicated a layer of partially melted material between 130 and 190 kilometers underground. That boundary marks the bottom of continental plates, argue Saikiran Tharimena, a seismologist at the University of Southampton in England, and colleagues. Their finding, reported in the Aug. 11 Science, may help resolve a longtime debate over the thickness of Earth’s landmasses. Estimating continental depth “has been an issue that’s plagued scientists for quite a while,” says Tim Stern, a geophysicist at Victoria University of Wellington in New Zealand, who wasn’t involved in the work. Rock fragments belched up by volcanic eruptions suggest that the rigid rock of the continents extends about 175 kilometers underground, where it sits atop slightly runnier material in Earth’s mantle. But analysis of earthquake vibrations along Earth’s surface have suggested that continents could run 200 or 300 kilometers deep, very gradually transitioning from cold, hard rock to hotter, gooier material.
6-7-17 There’s as much water in Earth’s mantle as in all the oceans
There’s as much water in Earth’s mantle as in all the oceans
The zone of mantle rock that sits 400 to 600 kilometres below our feet seems to be saturated with water. The deep Earth holds about the same amount of water as our oceans. That’s the conclusion from experiments on rocks typical of those in the mantle transition zone, a global buffer layer 410 to 660 kilometres beneath us that separates the upper from the lower mantle. “If our estimation is correct, it means there’s a large amount of water in the deep Earth,” says Fei Hongzhan at the University of Bayreuth in Germany. “The total amount of water in the deep Earth is nearly the same as the mass of all the world’s ocean water.” The results add to mounting evidence that there is much more water than expected beneath us, mostly locked up within the crystals of minerals as ions rather than liquid water. At least one team has previously discovered water-rich rock fragments in volcanic debris originating from the mantle. Another group has conducted experiments suggesting that the water at these depths was formed here on Earth rather than being delivered to the primordial planet by comets and asteroids. “The vast amount of water locked inside rocks of this deep region of the mantle will certainly force us to think harder about how it ever got there, or perhaps how it could have always been there since solidification of the mantle,” says Steven Jacobsen of Northwestern University in Illinois, who wasn’t connected with the new research. “It’s a key question about the evolution of the Earth, which extends to extrasolar planets as well.”
12-20-16 ‘Waterworld’ Earth preceded late rise of continents, scientist proposes
‘Waterworld’ Earth preceded late rise of continents, scientist proposes
Expansion of dry land may have enabled Cambrian explosion. The continents rose above sea level only a few hundred million years ago, a new proposal states. Before that time, Earth’s surface was mostly covered by water. Earth may have been a water world for much of its history, a new proposal contends. Just like in the Kevin Costner movie, the continents would have been mostly submerged below sea level. Previous proposals have suggested that Earth’s land area has remained comparatively unchanged throughout much of geologic time. But geoscientist Cin-Ty Lee of Rice University in Houston proposes that Earth’s continents didn’t rise above the waves until around 700 million years ago, when the underlying mantle sufficiently cooled. Though many scientists are unconvinced, that continental rise may have contributed to the rapid diversification of life known as the Cambrian explosion. “The Earth is cooling and that actually has manifestations that dictate how life goes,” Lee said December 15 at the American Geophysical Union's fall meeting.
12-19-16 Molten iron river discovered speeding beneath Russia and Canada
Molten iron river discovered speeding beneath Russia and Canada
A hot stream of molten iron that is 420 kilometres wide is moving westwards under North America and Siberia and has inexplicably tripled its speed over the past 15 years. Deep below our planet’s surface a molten jet of iron nearly as hot as the surface of the sun is picking up speed. This stream of liquid has been discovered for the first time by telltale magnetic field readings 3000 kilometres below North America and Russia taken from space. The vast jet stream some 420 kilometres wide has trebled in speed since 2000, and is now circulating westwards at between 40 and 45 kilometres per year deep under Siberia and heading towards beneath Europe. That is three times faster than typical speeds of liquid in the outer core. No one knows yet why the jet has got faster, but the team that discovered the accelerating jet thinks it is a natural phenomenon that dates back as much as a billion years, and can help us understand the formation of Earth’s magnetic fields that keeps us safe from solar winds.
12-19-16 Iron 'jet stream' detected in Earth's outer core
Iron 'jet stream' detected in Earth's outer core
Scientists say they have identified a remarkable new feature in Earth’s molten outer core. They describe it as a kind of "jet stream" - a fast-flowing river of liquid iron that is surging westwards under Alaska and Siberia. The moving mass of metal has been inferred from measurements made by Europe’s Swarm satellites. This trio of spacecraft are currently mapping Earth's magnetic field to try to understand its fundamental workings. The scientists say the jet is the best explanation for the patches of concentrated field strength that the satellites observe in the northern hemisphere. "This jet of liquid iron is moving at about fifty kilometres per year," explained Dr Chris Finlay from the National Space Institute at the Technical University of Denmark (DTU Space). “That might not sound like a lot to you on Earth's surface, but you have to remember this a very dense liquid metal and it takes a huge amount of energy to move this thing around and that's probably the fastest motion we have anywhere within the solid Earth,” he told BBC News.
12-14-16 World’s oldest water gets even older
World’s oldest water gets even older
The liquid is found deep down a mine in Canada. The world’s oldest water, which is locked deep within the Earth’s crust, just got even older. The liquid was discovered deep down in a mine in Canada in 2013 and is about 1.5 billion years old. But now, at the same site, scientists from the University of Toronto have found a deeper source of water that is at least 500,000 years more ancient. The research was presented at the American Geophysical Union Fall Meeting in San Francisco. Professor Barbara Sherwood Lollar, who led the team that made the discovery, told BBC News: “When people think about this water they assume it must be some tiny amount of water trapped within the rock. “But in fact it’s very much bubbling right up out at you. These things are flowing at rates of litres per minute - the volume of the water is much larger than anyone anticipated.” The first pool of ancient water was discovered 2.4km-down in a copper, zinc and silver mine.
11-23-16 Deepest water found 1000km down, a third of way to Earth's core
Deepest water found 1000km down, a third of way to Earth's core
Water identified far below the surface suggests Earth may contain many oceans’-worth of hidden water throughout the mantle. Earth’s mantle may contain many oceans’ worth of water – with the deepest 1000 kilometres down. “If it wasn’t down there, we would all be submerged,” says Steve Jacobsen at Northwestern University in Evanston, Illinois, whose team made the discovery. “This implies a bigger reservoir of water on the planet than previously thought.” This water is much deeper than any seen before, at a third of the way to the edge of Earth’s core. Its presence was indicated by a diamond spat out 90 million years ago by a volcano near the São Luíz river in Juina, Brazil.
8-9-16 The volcanos no one has ever seen.
The volcanos no one has ever seen.
Deep-sea volcanoes are so remote, until recently we did not even know they existed. Now we can see them like never before. We do not see them erupt, yet more than half of the Earth's crust can be attributed to their dramatic explosions. It sounds almost like a riddle. But when you understand the facts, the truth might be even more surprising. The remnants of hundreds of thousands of deep-sea eruptions lie on the ocean floor, deep below the surface of the water. Despite our ignorance, almost 70% of the Earth's crust is believed to be produced at mid-ocean ridges such as the Mid-Atlantic Ridge. These are the places where tectonic plates move away from each other. As they do so, magma can erupt into the space, forming new crust where the plates once were. These processes are so powerful that they form enormous volcanoes, similar to Iceland's 2014-2015 Bardarbunga volcano eruption.
7-27-16 New scenario proposed for birth of Pacific Plate
New scenario proposed for birth of Pacific Plate
Largest chunk of Earth’s crust born out of odd tectonic circumstances. Scientists have a new origin story for the Pacific tectonic plate, which now underlies most of the Pacific Ocean. The plate formed in a gap between three other plates, the scientists propose. A three-way tectonic tango may have led to the birth of what is now the largest chunk of Earth’s crust. By scrutinizing what little geologic evidence remains from 190 million years ago, researchers reconstructed the origins of the Pacific tectonic plate, which now covers a fifth of Earth’s surface. The plate formed during the early Jurassic period from a single point where three tectonic plates once met, the work suggests. The plate’s birthplace sat above the gravesite of a section of tectonic plate that sank into the planet’s depths, the researchers report July 27 in Science Advances. The remnants of that sunken plate remain embedded in Earth’s mantle.
7-27-16 Iron-loving elements tell stories of Earth’s history
Iron-loving elements tell stories of Earth’s history
Platinum, gold and other rare metals are treasure trove. Geochemists explore platinum, gold and other rare elements that are attracted to iron to understand how Earth's core formed billions of years ago. Four and a half billion years ago, after Earth’s fiery birth, the infant planet began to radically reshape itself, separating into distinct layers. Metals — mostly iron with a bit of nickel — fell toward the center to form a core. The growing core also vacuumed up other metallic elements, such as platinum, iridium and gold. By the time the core finished forming, about 30 million years later, it had sequestered more than 98 percent of these precious elements. The outer layers of the planet — the mantle and the crust — had barely any platinum and gold left. That’s why these metals are so rare today. By analyzing rare primordial materials, researchers are uncovering geochemical fingerprints that have survived essentially unchanged over billions of years. These fingerprints allow scientists to compare Earth rocks with moon rocks and test ideas about whether giant meteorites once dusted the inner solar system with extraterrestrial platinum and gold. Such research can help scientists learn how volatiles such as water may have spread, leaving some worlds water-rich and others bone-dry.
7-25-16 Ancient air bubbles could revise history of Earth’s oxygen
Ancient air bubbles could revise history of Earth’s oxygen
If new findings are correct, rise in gas preceded earliest animals. Ancient air embedded inside rock salt for 815 million years suggests that oxygen was already abundant when the first animals appeared. The microscopic air bubbles were trapped inside rectangular inclusions in the rock. Whiffs of ancient air trapped in rock salt for hundreds of millions of years are shaking up the history of oxygen and life on Earth. By carefully crushing rock salt, researchers have measured the chemical makeup of air pockets embedded inside the rock. This new technique reveals that oxygen made up 10.9 percent of Earth’s atmosphere around 815 million years ago. Scientists have thought that oxygen levels would not be that high until 100 million to 200 million years later. The measurements place elevated oxygen levels well before the appearance of animals in the fossil record around 650 million years ago, the researchers report in the August issue of Geology. “I think our results will take people by surprise,” says study coauthor Nigel Blamey, a geochemist at Brock University in St. Catharines, Canada. “We came out of left field, and I think some people are going to embrace it, and other people are going to be very skeptical. But the data is what the data is.” (Webmaster's comment: And that's what I report here, whether or not anyone likes it, including myself.)
How the Earth Was Made
Sioux Falls Scientists endorse How the Earth Was Made as it covers
the history of the planet Earth from its formation from dust
and molten rock to flourishing with human life.