• 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!
    1. 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.

    2. 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.

    3. 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. 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).

    4. 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.

    5. 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.

    6. 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.

  • Term Part of Speech Definition Encyclopedic Entry
    basin Noun

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

    Encyclopedic Entry: basin
    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.

    Encyclopedic Entry: continent
    desert Noun

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

    Encyclopedic Entry: desert
    elevation Noun

    height above or below sea level.

    Encyclopedic Entry: elevation
    explorer Noun

    person who studies unknown areas.

    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.

    Encyclopedic Entry: glacier
    ice sheet Noun

    thick layer of glacial ice that covers a large area of land.

    Encyclopedic Entry: ice sheet
    indigenous Adjective

    characteristic to or of a specific place.

    Encyclopedic Entry: indigenous
    island Noun

    body of land surrounded by water.

    Encyclopedic Entry: island
    karst Noun

    landscape made of limestone.

    Encyclopedic Entry: karst
    lake Noun

    body of water surrounded by land.

    Encyclopedic Entry: lake
    landscape Noun

    the geographic features of a region.

    Encyclopedic Entry: landscape
    meteorite Noun

    type of rock that has crashed into Earth from outside the atmosphere.

    Encyclopedic Entry: meteorite
    meteorology Noun

    study of weather and atmosphere.

    Encyclopedic Entry: meteorology
    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.

    Encyclopedic Entry: mouth
    North Pole Noun

    fixed point that, along with the South Pole, forms the axis on which the Earth spins.

    Encyclopedic Entry: North Pole
    pole of inaccessibility Noun

    place that is challenging to reach due to its remote access to geographical features that could provide access, such as the ocean.

    rain Noun

    liquid precipitation.

    Encyclopedic Entry: rain
    rift valley Noun

    depression in the ground caused by the Earth's crust spreading apart.

    Encyclopedic Entry: rift valley
    river Noun

    large stream of flowing fresh water.

    Encyclopedic Entry: river
    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.

    Encyclopedic Entry: source
    South Pole Noun

    fixed point that, along with the North Pole, forms the axis on which the Earth spins.

    Encyclopedic Entry: South Pole
    subduction Noun

    process of one tectonic plate melting, sliding, or falling beneath another.

    submersible Noun

    small submarine used for research and exploration.

    tectonic activity Noun

    movement of tectonic plates resulting in geologic activity such as volcanic eruptions and earthquakes.

    temperature Noun

    degree of hotness or coldness measured by a thermometer with a numerical scale.

    Encyclopedic Entry: temperature
    tributary Noun

    stream that feeds, or flows, into a larger stream.

    Encyclopedic Entry: tributary
    volcanic eruption Noun

    activity that includes a discharge of gas, ash, or lava from a volcano.

    watershed Noun

    entire river system or an area drained by a river and its tributaries.

    Encyclopedic Entry: watershed
    zircon Noun

    (zirconium silicate) hard, durable mineral containing zirconium, silicon, and oxygen.