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GeoStory MEDIA SPOTLIGHT

Earth's Extremes From the highest and lowest, to the hottest and coldest!

For the complete geostories with media resources, visit: http://education.nationalgeographic.com/media/earths-extremes/

From the thin air of Mount Everest to the intense pressure of the Challenger Deep, Earth is full of amazing extremes!

Record-setting extremes are always being updated. Scientists and explorers discover new materials and refine their measuring methods, upsetting our ideas of "biggest" or "oldest." Weather patterns set new records, identifying new locations for "wettest" or "driest." The dynamic activity of Earth itself—our rifting and shifting tectonic plates—redefines "highest" and "lowest."

Follow this GeoStory to learn about Earth's extremes, from highest and lowest, to hottest and coldest! QUESTIONS

According to the GeoStory, either Mount Everest, Nepal, or Mauna Kea, Hawaii, may be considered the “world’s tallest mountain.” Only the Challenger Deep, however, is considered the “world’s deepest trench.” Why? There are different ways to measure the “world’s tallest mountain,” but only one major way to measure the “world’s deepest trench.”

Mount Everest is the “world’s tallest mountain” when measuring by elevation above sea level. Mauna Kea is the “world’s tallest mountain” when measuring by elevation from the seafloor.

The Challenger Deep is the deepest point on Earth when measured by depth below sea level.

Scientists have long known that the Nile River’s source lies in the Ethiopian highlands, thousands of kilometers south of its mouth in the Mediterranean Sea. However, they still debate the length of the Nile. Why? Identifying the exact source of a river can be very, very difficult. Some scientists identify a river’s source as a tributary, others as a lake, still others identify it as the streams that flow into the lake or tributary. Scientists must then identify the source of those streams, and calculate which one is furthest from the mainstem of the river.

The Nile has two major tributaries, the White Nile and the Blue Nile. The source of the Blue Nile is Lake Tana, Ethiopia. The source of the White Nile, however, is still debated. Some scientists identify the source of the White Nile as Lake Victoria, Uganda. The primary source of Lake Victoria is the Kagera River, which has two sources: the Rukarara River in western Rwanda and the Ruvyironza River in Burundi. National Geographic considers these the most remote source of the Nile. Other scientists identify the source of the White Nile as Lake No, South Sudan. Depending on where scientists place the source of the White Nile, the length of the Nile itself may vary by hundreds of kilometers. The GeoStory identifies the province of Xinjiang, China, as the place farthest from the ocean. It is a terrestrial “pole of inaccessibility.” The oceanic “pole of inaccessibility” is the place in the ocean that is farthest from land. 1 of 4 Look at a world map. Where do you think the oceanic pole of inaccessibility lies? The oceanic pole of inaccessibility is in the South Pacific Ocean, at the coordinates 48°52.6′S 123°23.6′W. This point is nicknamed “Point Nemo,” after the fictional oceanic explorer Captain Nemo, created by science fiction writer Jules Verne. Point Nemo is about 2,688 kilometers (1,670 miles) from the nearest landmasses: Ducie Island (part of the Pitcairin Island group), Moto Nui (part of the Easter Island group), and Maher Island (Antarctica). According to the GeoStory, the world’s southernmost point of land is the South Pole. The world’s northernmost point of land is Kaffeklubben Island—not the North Pole! Why do you think the North Pole is not the most northern point of land on Earth? The geographic North Pole is in the Arctic Ocean, not on land. One of the Earth’s newest island is Niijima, created by the eruption of underwater volcanoes in the Pacific Ocean. Look at our map of volcanic eruptions around the world. Where else do you think new volcanic islands could be created? Answers will vary! Some volcanic regions in the ocean include the North Atlantic Ocean (near the island of Iceland), the western Indian Ocean (around the island of Madagascar), and the central Pacific—the islands of Hawaii. However, some of the most active volcanic regions—including the volcanic arc that created Niijima—circle the Pacific Ocean in the so-called “Ring of Fire.” The Ring of Fire stretches in a horseshoe shape from the area around New Zealand, up through the volcanic islands of Indonesia, Philippines, Japan, the U.S. state of Alaska, and Central and South America’s west coasts. According to the GeoStory, many of Earth’s extremes are constantly being updated by scientific discoveries and the Earth itself. Of the 20 “extremes” in the GeoStory, which ones do you think might be updated soon? Which ones do you think are unlikely to change? Answers will vary! The world’s highest and lowest elevations, and measurements of the world’s rivers and lakes are probably very stable and unlikely to change. Areas “furthest from another piece of land” and “furthest from the ocean” are also unlikely to change.

Although climate is fairly predictable, new temperature or precipitation records may be set in the near future.

Volcanic eruptions may create new islands in the ocean.

Explorers are discovering new cave systems all the time. One of these may turn out to be the world’s largest.

Scientists may also discover and date a material that is even older than the Jack Hills zircons.

VOCABULARY

Term Part of Speech Definition

basin noun a dip or depression in the surface of the land or ocean floor.

cave noun underground chamber that opens to the surface. Cave entrances can be on land or in water.

climatology noun study of the Earth's atmosphere.

continent noun one of the seven main land masses on Earth.

desert noun area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.

elevation noun height above or below sea level.

explorer noun person who studies unknown areas.

2 of 4 geology noun study of the physical history of the Earth, its composition, its structure, and the processes that form and change it. glacier noun mass of ice that moves slowly over land. ice sheet noun thick layer of glacial ice that covers a large area of land. indigenous adjective native to or characteristic of a specific place. island noun body of land surrounded by water. karst noun landscape made of limestone. lake noun body of water surrounded by land. landscape noun the geographic features of a region. meteorite noun type of rock that has crashed into Earth from outside the atmosphere. meteorology noun study of weather and atmosphere. mineral noun inorganic material that has a characteristic chemical composition and specific crystal structure. mouth noun place where a river empties its water. Usually rivers enter another body of water at their mouths.

North Pole noun fixed point that, along with the South Pole, forms the axis on which the Earth spins. pole of noun place that is challenging to reach due to its remote access to geographical features inaccessibility that could provide access, such as the ocean. rain noun liquid precipitation. rift valley noun depression in the ground caused by the Earth's crust spreading apart. river noun large stream of flowing fresh water. sandbar noun underwater or low-lying mound of sand formed by tides, waves, or currents. source noun beginning of a stream, river, or other flow of water.

South Pole noun fixed point that, along with the North Pole, forms the axis on which the Earth spins. subduction noun process of one tectonic plate melting or going beneath another. submersible noun small submarine used for research and exploration. tectonic noun movement of tectonic plates resulting in geologic activity such as volcanic eruptions activity and earthquakes. temperature noun degree of hotness or coldness measured by a thermometer with a numerical scale. tributary noun stream that feeds, or flows, into a larger stream. volcanic noun activity that includes a discharge of gas, ash, or lava from a volcano. eruption watershed noun entire river system or an area drained by a river and its tributaries. zircon noun (zirconium silicate) hard, durable mineral containing zirconium, silicon, and oxygen.

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