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Research shows thinning snow layers in the Rocky Mountains over hundreds of years

[ 2011-08-17 14:47]     字号 [] [] []  
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Research shows thinning snow layers in the Rocky Mountains over hundreds of years

FAITH LAPIDUS: This is SCIENCE IN THE NEWS in VOA Special English. I'm Faith Lapidus.

BOB DOUGHTY: And I'm Bob Doughty. Today, we tell about evidence of what some scientists are calling one of the last dinosaurs to exist. We tell about shrinking snow cover in North America's Rocky Mountains. We also talk about the Microsoft Imagine Cup finals in New York City.


FAITH LAPIDUS: Scientists think parts of the Earth may have sounded like this about 65 million years ago.


Then, suddenly, there was this:


FAITH LAPIDUS: For 30 years, scientists have found evidence that a huge rock from space, an asteroid, struck the Earth, killing all dinosaurs. They think the asteroid hit somewhere near the Gulf of Mexico. They say it was so powerful that a large amount of very hot dirt, dust, and water was thrown into the air and then began to circle the Earth. Those creatures not killed by the explosion soon died from extreme heat in the air.

BOB DOUGHTY: But wait! That may not be true, say scientists who have another idea. They agree that a large object from space probably hit our planet millions of years ago. But the scientists say that when that happened, the dinosaurs had all been dead for a long time.

Researchers from Yale University now think they know what really happened. The researchers found a bone from the head of a large dinosaur. They made the discovery in the Hell Creek area in the American state of Montana. The location of the bone is the clue to solving the mystery.

FAITH LAPIDUS: Geologists often study what scientists call the K-T boundary. That is a layer of soil and rock that marks major changes in the earth's history, like when the asteroid hit. When dinosaur bones are found in the lower parts of the K-T boundary, it suggests to some scientists that those animals died a very long time ago. They say the dinosaurs died long before the asteroid struck the Earth.

The bone that the Yale researchers found was much higher in that layer of rock and dirt. The researchers believe the bone was from a Triceratops that died 65 million years ago. The discovery was made just a few centimeters below what became the K-T boundary line. That means that this creature and probably many others were alive until the asteroid hit the earth.

Dinosaurs did not slowly die out millions of years ago. The huge asteroid, the scientists say, was the cause of their extinction. They were killed within a very short period of time when the violent explosion took place.

BOB DOUGHTY: Until now, geologists have been surprised by the lack of dinosaur bones and other fossils within three meters below the K-T line. This area is known among scientists as the "three meter gap." In the words of Yale University researcher Tyler Lyson, "This discovery suggests that the 'three meter gap' does not exist. At least some dinosaurs were doing just fine right up until the impact." And that makes this Triceratops the youngest dinosaur ever found, and the closest in time to the big asteroid's crash.

The results of the latest research on Montana dinosaurs were published last month in "Biology Letters."


FAITH LAPIDUS: Millions of people depend on the snowpack in North America's Rocky Mountains for water. But a new report says the amount of snow that stays on the ground there each spring has shrunk over the past 800 years. The report appeared last month in Science magazine.

The report says one cause of the thinning snowpack may be climate change, the warming of Earth's atmosphere. Gregory Pederson was a leader of the study. He works for the United States Geological Survey in Bozeman, Montana. He notes that during warmer weather, the northern Rocky Mountains usually receive rain instead of snow. The rain does not stay. And whatever snow that falls melts faster than normal.

Research shows thinning snow layers in the Rocky Mountains over hundreds of years

BOB DOUGHTY: Much research on the subject has been reported during the past ten years. Mr. Pederson says those studies identified human activity as the cause of some of the changes in the permanent snow. He says his team's findings support the results of the earlier studies.

GREGORY PEDERSON: "Attributing a proportion of those changes to human impacts has been done by well over a decade of observational and modeling studies... And what we are documenting here is that trees are telling the same story about snowpack change."

BOB DOUGHTY: Conditions in the ocean and the atmosphere that can make spring temperatures warmer also may influence the changes.

FAITH LAPIDUS: The research team studied places that produce major amounts of water. They include drainage basins, areas of water fed by three rivers -- the Colorado, the Columbia and the Missouri. The researchers say the basins provide 60 to 80 percent of the water needs of more than 70 million people.

The report says there were extremely unusual losses in water flowing into those areas in the late 20th century. This was found to be especially true after the 1980s.

BOB DOUGHTY: The news of reduced snowpack in the Rockies may surprise people who live there. Record-size snowpack and heavy flooding have affected the area recently. But Gregory Pederson says the unusually large snowpack demonstrates only one single weather event. He said the unusual conditions do not represent the climate over hundreds of years.

The research team measured tree rings to help learn about the climate over time. Trees form these rings, or circles of new growth, each year. The circles develop between the bark, or outside skin, of the tree and its core, or center. The lines help tell the age of the tree.

GREGORY PEDERSON "They [the trees] can be accurately dated to the calendar year."

FAITH LAPIDUS: To examine the rings, the team made small holes into several trees and removed small pieces of wood. He said the places where the trees were cut soon closed over and healed.

Mr. Pederson says tree rings can tell about moisture and cloud conditions. They also can provide climate information, including temperatures and the flow of waterways. In some cases, tree rings can show tree injuries from snow slides.


BOB DOUGHTY: Finally, hundreds of students from around the world gathered in New York City last month for the Microsoft Imagine Cup finals. They came to present their ideas for using technology to solve world problems.

Microsoft education director Suzi Levine says the nine-year-old program began mainly as a competition to create technology.

SUZI LEVINE: "When we realized that students really actually want to have a purpose for what they're creating, we introduced the idea of inspiring them with the UN Millennium Development Goals and suggesting that they use those for their muse."

BOB DOUGHTY: New sources for ideas this year included intergovernmental and nongovernmental organizations.

SUZI LEVINE: "This past year we also rolled out something called the Imagine Cup Solve This library, where IGOs, NGOs and nonprofits can submit some of the technical challenges that they would like students to consider for their solutions."

FAITH LAPIDUS: Microsoft says over 350,000 high school and college students registered for the recent competition. Judges chose more than 400 of them to attend the finals.

Ms. Levine says several teams were inspired by current events, including floods last year in Thailand.

SUZI LEVINE: "One from Thailand [was] called NewKrean, where they created a Windows Phone 7 application that allows you to broadcast your location to your social network of friends so that you can be more easily rescued."

FAITH LAPIDUS: Students competed in nine categories. For example, in software design the top prize of 25,000 dollars went to Team Hermes from Ireland. The students developed a device for cars to collect information on road conditions, driving behavior and traffic incidents.

A team from Taiwan's National Tsing Hua University won first place in the embedded development category. They developed a network of wireless devices to help plot the safest escape routes during a fire.

Next year, the awards ceremony will take place in Australia.


BOB DOUGHTY: This SCIENCE IN THE NEWS was written by Jim Tedder, Jerilyn Watson and June Simms, who was also our producer. I'm Bob Doughty.

FAITH LAPIDUS: And I'm Faith Lapidus. You can find transcripts, MP3s and podcasts of our programs at voaspecialenglish.com. Join us again next week for more news about science in Special English on the Voice of America.

Triceratops: a herbivorous dinosaur of the genus Triceratops, of the Cretaceous Period, having a bony plate covering the neck, a large horn above either eye, and a smaller horn on the nose 三角恐龙

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(来源:VOA 编辑:崔旭燕)