50 Fun Facts About Physical Geography

Which continent, the driest and windiest on Earth, is classed as the largest desert in the world?

Antarctica is a desert because deserts are defined by how little precipitation falls, not by heat. Its coast gets over 200 mm a year and the interior far less.

Which supercontinent joined nearly all of Earth's land before it began to break apart about 175 million years ago?

Pangaea was C-shaped and stretched between the polar regions, surrounded by the superocean Panthalassa. Its name comes from Greek words for all and Mother Earth.

What name is given to the tectonic belt of volcanoes and earthquakes around the rim of the Pacific Ocean?

The Ring of Fire is where about 90% of the world's earthquakes strike, including most of the largest ever recorded.

Which trench in the western Pacific Ocean holds the Challenger Deep, the deepest known point of any ocean?

The Mariana Trench is so deep that its lowest point lies more than 2 km farther from sea level than the peak of Mount Everest.

Which natural cycle is caused by the tilt of Earth's axis rather than its changing distance from the Sun?

The seasons come from Earth's axial tilt, which changes how high the Sun climbs in the sky. Earth is actually closest to the Sun in January, in the middle of the northern winter.

Which seismologist's name is on the magnitude scale first used in 1935 to compare earthquake sizes?

Charles Richter developed the scale with Beno Gutenberg at Caltech. Most agencies now report quakes on the moment magnitude scale, though news reports still credit the old one.

Which series of ocean waves, usually caused by earthquakes, can cross the deep Pacific at about 500 miles per hour?

A tsunami slows to under 50 mph as it reaches shallow water near the coast, and grows in height as it does. Far out at sea it may pass unnoticed as a slight swell.

Which river discharges more water than the next seven largest independent rivers combined?

The Amazon is the largest river in the world by volume of water, though its claim to be the longest is disputed with the Nile.

Which gas makes up about 78 percent of the dry air in Earth's atmosphere, far more than oxygen?

Nitrogen dominates dry air, with oxygen at about 21%. Argon, at just under 1%, comes third, well ahead of carbon dioxide at 0.04%.

What name is given to tropical cyclones that form in the northwestern Pacific, near Japan and the Philippines?

Typhoons are the same kind of storm as Atlantic hurricanes; only the name changes with the ocean. The northwestern Pacific produces almost a third of the world's tropical cyclones.

Which mountain range was uplifted by the collision of the Indian tectonic plate with the Eurasian plate?

The Himalayas include Mount Everest, the highest peak on Earth. Deeper layers of the Indian plate kept pushing north under Tibet, thickening its high plateau.

Which California fault is the boundary where the Pacific plate slides past the North American plate?

The San Andreas Fault runs roughly 750 miles through California, and a rupture along it caused the 1906 San Francisco earthquake.

Which reversing wind brings heavy summer rainfall to India from the Bay of Bengal and Arabian Sea?

The monsoon blows because land warms more quickly than the ocean in the hot months, drawing moist sea air inland. In the colder months the cycle is reversed.

Which treeless biome of the far north has a subsoil of permafrost that stays frozen all year?

Tundra soil locks away large stores of carbon, which escape as methane and carbon dioxide when the frozen ground thaws.

Which line of 0° longitude was fixed at Greenwich by an 1884 international conference in Washington?

The Prime Meridian at Greenwich won the votes of 22 countries at that conference. France abstained and kept using its own Paris meridian until 1911.

Which gas forms a layer in the stratosphere that absorbs most of the Sun's ultraviolet radiation?

Ozone in that layer was being depleted by industrial chemicals called CFCs, research revealed in 1985, and the Montreal Protocol then capped their production.

Which landform builds up where a river such as the Mississippi slows at its mouth and drops sediment?

A delta is named after the triangular Greek capital letter, because that is the shape the mouth of the Nile makes on a map.

Which twice-yearly event puts the Sun directly above the equator, making day and night almost equal?

An equinox never gives exactly equal day and night, because the Sun is a disk rather than a point and the atmosphere bends its light.

Which coordinate measures position north or south, from 0° at the equator to 90° at each pole?

Latitude is drawn on maps as parallels, circles that run east to west and never meet, unlike the north-south lines, which all converge at the poles.

Which molten material beneath Earth's surface becomes known as lava once a volcano erupts it?

Magma that never reaches the surface can solidify underground instead, forming intrusions such as dikes and sills, and it is the source of all igneous rocks.

Which lowest layer of Earth's atmosphere holds 80% of its mass and is where most weather occurs?

The troposphere takes its name from a Greek word for turning, because churning air keeps it mixed. It also holds 99% of the atmosphere's water vapor.

Which coarse-grained igneous rock, formed as molten rock cools slowly underground, makes up Yosemite's El Capitan?

Granite is made mostly of quartz and feldspar. El Capitan is a single block of it rising about 900 metres from the floor of Yosemite Valley.

Which parallel marks the northernmost point where the Sun can be seen directly overhead, on the June solstice?

The Tropic of Cancer was named when the Sun sat in the constellation of the Crab at the June solstice. A slow wobble of Earth's axis has since moved that spot into Taurus.

Which water-cycle process returns moisture to the air through tiny pores in the leaves of plants?

Transpiration accounts for nearly all the water a plant takes up: only about 0.5 to 3 percent of what the roots absorb is kept for growth.

Which type of volcano, built by highly fluid lava into a broad, gently sloping profile, includes Mauna Loa?

Shield volcanoes are named for their low profile, like a shield lying on the ground. Their runny lava travels farther than the sticky lava of steeper stratovolcanoes.

Which term names the area of land where all flowing surface water converges on a single river mouth?

A drainage basin is commonly called a watershed in North America, though elsewhere that word means only the dividing line between two of them.

Which underground layer of water-bearing rock or sediment, like the Ogallala under the Great Plains, feeds wells?

An aquifer can be pumped faster than it refills: the Ogallala, one of the world's largest, is being rapidly depleted in places by farm and city use.

Which desert, walled in by two mountain chains that block ocean moisture, is the driest outside the poles?

The Atacama runs for 1,600 km along the coast of northern Chile, where the Andes and the Chilean Coast Range shut out damp air from both sides.

Which term names the dry area on the leeward side of mountains, where air has already dropped its moisture?

A rain shadow forms because moist air cools and sheds its water climbing the windward slope, then warms as it sinks. California's Sierra Nevada casts one over the land to its east.

Which warm Atlantic current flows up the US East Coast and then veers toward Northwest Europe?

The Gulf Stream was first met by Europeans on Juan Ponce de León's 1513 voyage to Florida, and Spanish ships then rode it home from the Caribbean.

Which Pacific warming phase did Peruvian fishermen name after the Christ Child, as it appeared around Christmas?

El Niño is the warm phase of a cycle whose cool phase is called La Niña. The fishermen's phrase began as a name for a warm current flowing south along their coast.

Which effect of Earth's rotation deflects moving air and water to the right in the Northern Hemisphere?

The Coriolis effect is named after a French scientist whose 1835 paper was about water wheels, not weather. South of the equator the deflection is to the left.

Which steady east-to-west air currents near the equator did sailing-ship captains use for centuries to cross oceans?

The trade winds take their name from an old sense of the word trade meaning path or track, not from commerce.

Which process breaks rock down in place, by frost or plant roots, without carrying the fragments away?

Weathering happens on the spot, which sets it apart from erosion, where water, ice, wind or gravity move the material. Frost is its most important physical form.

Which process sees a heavier tectonic plate dive beneath another and sink into Earth's mantle?

Subduction recycles old ocean floor back into the mantle, and fluids released by the sinking plate trigger volcanoes in the plate above.

Which German meteorologist proposed continental drift in 1912, an idea geologists did not accept until the 1960s?

Alfred Wegener was known in his lifetime mainly for weather science and polar research, and he joined several expeditions to Greenland.

Which climate type, with dry summers and wet winters, is shared by coastal California and central Chile?

The Mediterranean climate sits almost only on the western sides of continents, and its tough shrubland is called chaparral in California and matorral in Chile.

Which towering cloud type, known as a thunderhead, can spread into a flat anvil-shaped top?

Cumulonimbus clouds flatten into an anvil where their rising air meets a lid of warmer air high above, and they can produce lightning, large hail and tornadoes.

Which lines on a weather map join places of equal atmospheric pressure reduced to sea level?

Isobars take their name from a Greek word for weight, and the way they are spaced lets forecasters read the strength and direction of the wind.

Which fertile grasslands cover much of central Argentina, all of Uruguay and Brazil's southernmost state?

The Pampas take their name from a Quechua word for plain, and much of the land is now used to raise cattle.

Which long, narrow sea inlet with steep sides fills a valley carved by a glacier, as on Norway's coast?

A fjord is usually deeper than the sea outside it: Norway's Sognefjord reaches as much as 1,300 m below sea level.

Which lake, the deepest in the world, holds more water than all the North American Great Lakes combined?

Baikal lies in southern Siberia and is also the world's oldest lake, at 25 to 30 million years. It contains around 19% of the planet's unfrozen fresh water.

Which dark, stable organic matter in soil is left when plant and animal remains have fully decomposed?

Humus is simply the Latin word for ground or earth, and the more of it a soil layer holds, the darker that layer tends to look.

Which funnel-shaped inlet on Canada's Atlantic coast has the highest tidal range in the world?

The Bay of Fundy has tides that can reach about 16 metres, against an average of about one metre worldwide, because the water resonates in its funnel-shaped basin.

Which landscape of sinkholes, caves and underground streams forms where water dissolves limestone?

Karst is named after a plateau between Italy and Slovenia. The word reached Europe's scholars in 1689, in an account of rivers there flowing underground.

Which ridge of unsorted rock debris is left at the side or snout of a glacier that carried it there?

A moraine at a glacier's foot is called terminal and marks the farthest point the ice ever reached. The word comes from a Savoyard term for a mound of earth.

Which crescent-shaped sand dune, formed by wind from one main direction, has two horns pointing downwind?

A barchan takes its name from Kazakh. Its gentle slope faces into the wind, while the steep slip face on the far side rests at about 30 to 35 degrees.

Which Ecuadorian volcano's summit is the farthest point on Earth's surface from the planet's center?

Chimborazo stands 6,263 m above sea level, well below Mount Everest, but it sits on the equatorial bulge, where Earth is at its widest.

Which wind-blown, silt-sized sediment forms deposits over a hundred metres thick in northwestern China?

Loess splits along vertical lines, so it is easily dug out, and people in parts of China have long carved cave homes into it.

Which term for the fraction of sunlight a surface reflects is about 0.9 for fresh snow and 0.04 for charcoal?

Albedo comes from the Latin for whiteness. When snow starts to melt, the surface reflects less and absorbs more radiation, which melts still more snow, a loop called ice-albedo feedback.