Instructions: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Input: No one really knows how the High Plains got so high. About 70 million years ago, eastern Colorado, southeastern Wyoming, western Kansas and western Nebraska were near sea level. Since then, the region has risen about 2 kilometers, leading to some head scratching at geology conferences. 
  
 Now researchers at the Cooperative Institute for Research in Environmental Sciences (CIRES) and the Department of Geological Sciences at the University of Colorado Boulder have proposed a new way to explain the uplift: Water trapped deep below Earth's crust may have flooded the lower crust, creating buoyancy and lift. The research appears online this week in the journal Geology and could represent a new mechanism for elevating broad regions of continental crust. 
  
 "The High Plains are perplexing because there is no deformation -- such as major faults or volcanic activity -- in the area to explain how this big, vast area got elevated," said lead author Craig Jones, a CIRES fellow and associate professor of geology at CU-Boulder. "What we suggest is that by hydrating the lower crust, it became more buoyant, and the whole thing came up." 
  
 "It's like flooding Colorado from below," Jones said. 
  
 Jones and his colleagues propose the water came from the subducting Farallon oceanic plate under the Pacific Ocean 75 to 45 million years ago. This slab slid underneath the North American continental plate, bringing with it a tremendous amount of water bound in minerals. Trapped and under great pressure and heat, the water was released from the oceanic plate and moved up through the mantle and toward the lower crust. There, it hydrated lower crust minerals, converting dense ones, like garnet, into lighter ones, such as mica and amphibole. 
  
 "If you get rid of the dense garnet in the lower crust, you get more elevation because the crust becomes more buoyant," Jones said. "It's like blowing the water out of a ballast tank in a submarine." 
  
 Jones had the lightbulb moment for this idea when colleagues, including co-author Kevin Mahan, were describing xenoliths (pieces of crust ejected by volcanic eruptions) from across Wyoming and Montana. The researchers were reviewing the xenoliths' composition and noticed something striking. Xenoliths near the Canadian border were very rich in garnet. But farther south, the xenoliths were progressively more hydrated, the garnet replaced by mica and other less-dense minerals. In southern Wyoming, all the garnet was gone. 
  
 Upon hearing these findings, Jones blurted out, "You've solved why Wyoming is higher than Montana," a puzzle that other theories haven't been able to explain. 
  
 At the time, Mahan, a CU-Boulder assistant professor of geological sciences, noted that the alteration of garnet was thought to be far too ancient, from more than a billion years ago, to fit the theory. But since then, he and another co-author, former CU-Boulder graduate student Lesley Butcher, dated the metamorphism of one xenolith sample from the Colorado Plateau and discovered it had been hydrated "only" 40-70 million years ago. 
  
 Past seismic studies also support the new mechanism. These studies show that from the High Plains of Colorado to eastern Kansas, the crustal thickness or density correlates with a decline in elevation, from about 2 kilometers in the west to near sea level in the east. A similar change is seen from northern Colorado north to the Canadian border. In other words, as the crust gets less hydrated, the elevation of the Great Plains also gets lower. 
  
 "You could say it's just by happenstance that we seem to have thicker more buoyant crust in higher-elevation Colorado than in lower-elevation central Kansas," Jones said, "but why would crust buoyancy magically correlate today with topography if that wasn't what created the topography?" 
  
 Still, Jones is quick to point out that this mechanism "is not the answer, but a possible answer. It's a starting point that gives other researchers a sense of what to look for to test it," he said. ||||| DENVER (AP) — Geologists may finally be able to explain why Denver, the Mile High City, is a mile high: water. 
  
 FILE - In this April 14, 2003 file photo, the downtown Denver skyline is pictured, with the foothills, and the Rocky Mountains in the background. Geologists say they might finally know why the Mile High... (Associated Press) 
  
 A marker carved in one of the west steps of the State Capitol denotes the "one mile above sea level" elevation in Denver on Friday, March 13, 2015. In an article published in March 2015, geologists from... (Associated Press) 
  
 A new theory suggests that chemical reactions, triggered by water far below the Earth's surface, could have made part of the North American plate less dense many millions of years ago, when the continents we know today were still forming. 
  
 Because plates float on the Earth's mantle, parts of the Western United States might have risen, like an empty boat next to one with a heavy cargo, pushing the vast High Plains far above sea level, according to the theory formulated by geologists Craig Jones and Kevin Mahan at the University of Colorado-Boulder. 
  
 Their work appeared last week on the website of the journal Geology, and is a big deal for Denver, where the 5,280-foot elevation is a point of pride and a big part of the city's identity. At Coors Field, where the Colorado Rockies play baseball, a single row of purple seats interrupts about 50,000 green ones, marking the mile-high line in the grandstand. 
  
 Geologists have long been puzzled by how the High Plains could be so big, so high and so smooth. The plains descend gently from roughly 6,000 feet to 2,000 feet above sea level as they stretch for thousands of square miles, from the Texas Panhandle to southern Montana, and from western Kansas to the foothills of the Rocky Mountains in Colorado. 
  
 It's well established that much of the West was still at sea level 70 million years ago, and that tectonic shifts don't fully explain the High Plains' altitude. The lifting began long after the ancient Farallon oceanic plate was shoved deep under a vast part of western North America and then settled deep into the planet's mantle over millions of years. 
  
 Why? "Crustal hydration," Jones and Mahan theorize. 
  
 They suggest that water that had been locked in minerals in the Farallon plate was released because of pressure from the overlying rock and heat emanating from the Earth's core. The water then rose into the continental plate, setting off chemical reactions that turned garnet and other dense minerals into mica and other less heavy minerals, making vast areas of the crust lighter. 
  
 Jones said the Earth's crust under the High Plains "floats higher" over the mantle, much like a plank of buoyant balsa wood rises higher in the water than a plank of dense pine. 
  
 The reason crustal hydration happened where and when it did has to do with how steeply the oceanic plate descended, Jones said. At some point, the angle at which the plate was descending became shallower, enabling the released water to rise for reasons that remain unclear, he said. 
  
 Few geological formations appear so uniform on such a vast scale as the High Plains — the only other known location in the world that's similar is in southern Africa, Jones said. The prevailing theory there is different, involving some other source of buoyance, Mahan said. 
  
 The composition of rocks found in the High Plains is strong evidence in favor of the hypothesis, Jones said, but it needs more testing, and that was one reason for publishing it. 
  
 "Do we think this is 'the' answer? No. Could it be 'an' answer? I suppose it's possible," said Jones, who is also a fellow at the Cooperative Institute for Research in Environmental Sciences, a partnership of CU and the National Oceanic and Atmospheric Administration. 
  
 The theory has merit, according to Ken Dueker, a professor of geology and geophysics at the University of Wyoming. 
  
 "It's a plausible hypothesis that has some data to support it," said Dueker, who was not part of the team that devised it. One unanswered question, which Jones and Mahan raised in the journal Geology, is what channeled the water up into the North American plate, Dueker said. 
  
 The Farallon plate also helped form the Rocky Mountains just west of Denver, which soar as high as 14,433 feet. As it moved under the continent, friction caused the North American plate above to compress horizontally, like a rug that bunches up if a foot is dragged across it, geologists say. 
  
 Cracks opened from that horizontal pressure, and one side was shoved higher than the other, creating the Rockies. 
  
 Not knowing why Denver is a mile high is a little awkward for Colorado geologists. Jones recalls having to tell a British TV producer a few years ago that he couldn't explain it. 
  
 "We probably need to figure this one out, guys, because it's kind of embarrassing," Jones said. 
  
 ___ 
  
 Follow Dan Elliott at http://twitter.com/DanElliottAP |||||
Output:
What makes the High Plains so darned high? Well, geologists say, maybe the Earth just got lighter and floated up like a plank of wood for millions of years. In the journal Geology, experts say water beneath the Western US may have infiltrated an area of the continental plate and made it light enough to rise some 6,000 feet, the AP reports. It started millions of years ago when the West was mostly at sea level. The Farallon oceanic plate had slid under North America and, the theory goes, reacted to pressure from above and heat from below by releasing water. That water rose up into densely packed minerals, turning them into minerals so light that the Earth's crust slowly "floated" and became the High Plains. But it's still just a theory, says co-author Craig Jones. "Do we think this is 'the' answer? No," says Jones, a geology professor at the University of Colorado Boulder. Yet the mystery is an awkward one for Colorado geologists: "We probably need to figure this one out, guys, because it's kind of embarrassing," Jones once said in a TV interview. The problem is that no deformations like volcanic activity or major faults are there to explain the High Plains, he tells Science Daily. "What we suggest is that by hydrating the lower crust, it became more buoyant, and the whole thing came up," he says. "It's like flooding Colorado from below." Seismic studies support the theory, too, saying the Earth's crust is lighter and more hydrated at higher elevations. (Now, did a "golden spike" in the geologic record kickstart the "Age of Man" in 1610?)