Way to go: follow a teen on a record-breaking climb to the top of the world.
Last spring, 18-year-old Samantha Larson got to see the world from an unusual angle: She was standing atop its highest point. On May 17, 2007, after four days of skilled climbing, she reached Mount Everest's summit.
By successfully scaling the highest mountain on Earth, which rises 8,850 meters (29,035 feet) above sea level, the teen from California broke a world record: Samantha became the youngest person ever to climb The Seven Summits (see map, p. 17). Towering Mount Everest--which is part of the Himalayan mountain range that separates the countries of Nepal and China--is often considered a climber's ultimate challenge. But guess what? The mountain wasn't always so lofty.
Earth is a dynamic planet, with mountain ranges constantly being formed and worn away over time. As a result, Mount Everest's appearance has been changing for millions of years. But many scientists think that the mountain is now undergoing dramatic changes of another sort--those brought on by global warming. If they're right, future mountaineers will face a set of challenges unimagined by today's climbers.
Awe-inspiring Mount Everest did not always exist. In fact, where it stands today was once a shallow sea. Just like all other mountains, Mount Everest and the rest of the Himalayas started to develop as a result of shifting tectonic plates, or moving slabs of rocks that make up Earth's crust (see Nuts and Bolts, p. 18).
Approximately 65 million years ago, Earth's continents weren't located where they are today. "India was an island," says Mike Searle, a geologist at Oxford University in England. "Then the Indian plate started moving northward across the [former body of water called the] Tethys Sea." Approximately 50 million years ago, India collided with what was then the southern edge of the Asian plate. "As the plates began squeezing together, the rocks in the collision zone jostled and folded," says Rick Law, a geologist at Virginia Tech. The rocks that were originally part of the seafloor between India and Asia began pushing upward to form the Himalayas, including Mount Everest.
This mountain-building process, called orogeny, is not over. "We know from [satellite-based location-tracking devices called] Global Positioning System that India is still moving north relative to stable Asia, and the Himalayas is still rising," says Searle. As a result, Mount Everest is estimated to be rising by approximately 0.5 centimeters (0.2 inches) per year.
PERMIT TO SCALE
Ever since 1953, when Edmund Hillary and Tenzing Norgay became the first people known to reach the top of Mount Everest, more than 2,000 climbers have successfully followed in their footsteps. However, hundreds of others have perished in their summit attempt. To prepare for her treacherous climb, Samantha spent two months building her mountaineering skills in Nepal.
Like most climbers, Samantha's first task was to set up a temporary home, or base camp, partway up Mount Everest. Along with her climbing team, she scaled the mountain's lower slopes made of cliffs of granite. This hard igneous rock formed when magma (molten rock) from deep underground rose up and cooled and hardened over time, says Searle.
Once arriving at the base camp, located at 5,364 meters (17,600 feet) above sea level, Samantha set up her tent there so she could acclimate to living at such a high altitude. That is a necessary step for all climbers because as elevation increases, oxygen levels decrease, so a person not used to a lower oxygen intake can get sick. When Samantha's body finally became accustomed to her new environment, she trained for her big trek by making a series of short climbs up the mountain from base camp.
Steep and icy, Mount Everest is challenging to scale. Samantha, like many mountaineers, depended on Sherpas (natives of the region) to guide her uphill and help carry her gear.
Samantha's path to the summit began at Khumbu Icefall (see photo, p. 16). This glacier, or massive moving ice sheet, slides down the mountain at a rate of approximately 1.2 m (4 ft) per day. It's also peppered with cavernous cracks in the ice. "Some of the crevasses are about 80 feet deep," says Samantha. To cross them, Sherpas placed ladders across the cracks for climbers to walk over like a bridge.
Samantha's next feat was to scale Lhotse Face, a 1,219 m (4,000 ft)-tall wall of solid ice. Part of this challenge involves waiting for the right weather. "When the sun is beating down, the ice melts," says Samantha. "When it's colder, your crampons (spikes attached to boots) really have something to dig into."
After climbing Lhotse Face, she took on South Col, the same path taken by Hillary and Tenzing, to reach the snow-covered summit. "It was amazing to be there," says Samantha.
But will future generations of climbers see the same snowy view as Samantha did from the mountaintop? Scientists aren't sure. That's because global warming is changing the surface of Everest.
An increase in Earth's average temperature is causing glaciers on Everest to recede. "If you compare the glaciers [now] to photos taken of them in the 1920s, they look very different," says Law. Global warming also is leading ice to go through cycles of freeze and thaw more often. "This causes rocks to become more unstable; they can shatter much more easily," says Searle. So in addition to tackling many of the same challenges faced by Samantha, who is now a freshman at Stanford University in California, future Everest climbers also may need to think about the unpredictable conditions caused by climate change.
RECORD BREAKER: Samantha Larson, pictured here on Mount Everest, began climbing mountains at age 12. Her father is her climbing partner.
THE SEVEN SUMMITS
The map below shows the highest mountains on each of Earth's seven continents: Africa, Antarctica, Asia, Europe, North America, South America, and Australia/Oceania. Some people argue that the Carstensz Pyramid in Indonesia instead of Australia's Mt. Kosciuszko should be included. That's because it is the highest summit in Oceania, a region that includes Australia, New Zealand, and many nearby islands.
nuts & bolts
Like all mountains, the world's tallest peak formed as a result of the constant shifting of Earth's rocky plates. The collision of the Indian and Asian plates created the Himalayan mountain chain.
65 MILLION YEARS AGO
Earth's continents were located in different spots than they are today. India was separated from Asia by a shallow sea. India drifted northward at a rate of a few centimeters per year.
60 MILLION YEARS AGO
The Indian plate began to slide northward beneath the Asian plate. The motion started to close the Tethys Sea. The seawater seeped into the deeper oceans on either side of the collision.
40 MILLION YEARS AGO
The Indian plate continued to push against Asia, smashing the continents together. Sediment that had formed at the bottom of the Tethys Sea was crushed between the Asian and Indian continents.
20 MILLION YEARS AGO
The Tethys Sea had completely disappeared. Rocks that once lay on the seafloor were folded and squeezed upward to form the Himalayan mountain range, which includes Mount Everest.
Continued plate motion has brought the continents to their current positions on Earth. India has traveled farther than any other landmass, creating the planet's tallest point.
Visit this Web site for an interactive lesson on plate tectonics: www.pbs.org/wgbh/aso/tryit/tectonics/
DID YOU KNOW?
* In Nepal, Mount Everest is called Sagarmatha, which means goddess of the sky. * The leading cause of death on Mount Everest is avalanches.
* How might global warming affect not only Mount Everest, but other natural formations?
GEOGRAPHY: Do research to learn about the Sherpa people. Then create a tip sheet to help visitors to Mount Everest better understand their hosts. Include five phrases in the Sherpa language that visitors should learn.
* For extensive information on Mount Everest, check out this Web site: www.nationalgeographic.com/everest/
* For resources and lesson plans on Mount Everest, visit: www.everestnews.com/lessonplan.htm
DIRECTIONS: Complete the following as you read the story on pages 16 to 18.
1. Look at the images on pages 16 to 18. Then read the article's headline and subheadlines. Based on this information, what do you think this article is about? Why?
2. Below are three vocabulary words. Read the story to find the definitions of these words.
3. In the section titled "Moving Mountains," the author describes what Earth looked like 65 million years ago. List three differences in the way Earth looked then compared with today.
4. The article states: The mountain-building process is far from over. Predict how the Himalayan region may change in the next 20 million years.
5. Use the information in the article to defend or dispute this statement: In the future, it will be more difficult for climbers to summit Mount Everest. (Hint: Defend means to explain why a statement is correct. Dispute means to explain why a statement is incorrect.)
6. Study the diagram on p. 18. In your own words, summarize the process that led to the formation of the Himalayan mountain range.
1. Answers will vary
2. Tectonic plates: Tectonic plates are moving slabs of rock that make up Earth's crust. Orogeny: Orogeny is the process of mountain building. Global warming: Global warming is an increase in Earth's average temperature.
3. 65 million years ago, the continents were not in their present positions, India was an island, and the Himalayan mountain range did not exist.
4. Answers will vary. Here are some possible responses: In the next 20 million years, the Himalayan mountain range will be higher than it is today, the tectonic plates will continue to move relative to their current positions, and India will likely be a different shape.
5. Answers will vary but should include the following information: Defend: If global warming continues, it will be more difficult for climbers to summit Mount Everest That's because when ice undergoes increased cycles of freeze and thaw, rocks become more unstable. Also, melting ice makes it more difficult to use crampons to scale remaining ice walls
6. Answers will vary
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|Title Annotation:||EARTH: PLATE TECTONICS|
|Date:||Jan 14, 2008|
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