100 Fun Facts About Glacier

A glacier forms where the accumulation of snow exceeds what, over many years?

Its ablation, the ice lost to melting, evaporation and calving: while snowfall keeps pace a glacier holds steady or grows, and once losses pull ahead its front starts to retreat.

Glaciers are found on every continent except the mainland of which one?

Australia: glaciers last sat on its Snowy Mountains during the ice age, and the small lakes they scooped out near Mount Kosciuszko are still there.

Since 1984, which two countries' troops have faced off on the Siachen Glacier, often called the world's highest battlefield?

India and Pakistan: most of the soldiers lost there died not in combat but from avalanches, exposure and altitude sickness, and the shelling stopped only with a ceasefire in 2003.

At the peak of the last ice age, ice sheets buried nearly all of which present-day country?

Canada: the ice sheet that smothered it also carved out the basins that later filled with meltwater to become the Great Lakes.

Which mummy, more than 5,000 years old, did hikers find melting out of glacier ice in the Alps in 1991?

Ötzi: he did not simply freeze on the mountain pass, because an arrowhead lodged in his left shoulder shows that someone shot him.

Why does glacier ice look blue?

It absorbs red light and has no air bubbles: ordinary ice looks white because trapped bubbles scatter every colour, but a glacier's weight squeezes them out, so light sinks deep enough to lose its red.

Who argued that glaciers had carved Yosemite Valley, against a state geologist who said its floor had dropped?

John Muir: he found a living glacier in the high Sierra in 1871 to back his case, though geologists now say he went too far in thinking ice alone had carved the whole valley.

Glacier National Park, where the ice has been shrinking since about 1850, is in which US state?

Montana: the park has had to replace its own exhibits warning that the glaciers would be gone by 2020, because the ice, though still shrinking, outlasted that forecast.

What do glaciologists call a dome of glacier ice covering less than 50,000 square kilometres, such as Europe's Vatnajökull?

An ice cap: past that size the same kind of dome is called an ice sheet, and although several spread across the northern continents in the last ice age, only two are left today.

If Earth's two great ice sheets melted completely, roughly how far would global sea level rise?

About 70 metres, around 60 of them from Antarctica alone: enough to flood every coastal city on the planet and give each continent a new shoreline.

What are rocky peaks that poke up through an ice sheet called?

Nunataks, from an Inuit word: botanists once thought Arctic plants sat out the ice ages on these bare summits, though later studies have cast doubt on the idea.

Glaciers that end in the sea and calve icebergs are known as what?

They go through centuries-long cycles of advance and retreat that are far less tied to climate than other glaciers.

A glacier that is at melting point from surface to base all year round is called what?

Temperate: because its ice sits at melting point, water reaches the bed and lets the whole glacier slide over the rock, while a polar glacier stays frozen to its bed and barely slips at the base.

What is the granular, partly compacted snow that is on its way to becoming glacial ice called?

Firn: the name comes from a Swiss German word meaning 'of last year', because it is snow that has outlasted at least one summer's melt without yet turning to ice.

What is the armchair-shaped hollow, also called a corrie or cwm, where a glacier usually begins?

A cirque: snow packs into the hollow until ice spills over its lip, and when the glacier finally melts away the bowl is often left holding a small mountain lake called a tarn.

What sets a glacier apart from a year-round snowfield?

It moves under its own weight: once the ice is some tens of metres thick, the pressure makes its lower layers deform, and the whole mass begins to creep.

What nickname do glaciologists give the balls of moss that roll around the surface of some glaciers?

Glacier mice: no relation to rodents, they roll about the ice gathering moss as they go, and each ball shelters its own tiny community of springtails, worms and water bears.

When a glacier is said to be retreating, what is its ice actually doing?

Still flowing downhill: a glacier works like a conveyor belt that never reverses, and its front 'retreats' only because the end melts away faster than new ice arrives.

What are the deep cracks that open in the brittle surface ice of a glacier called?

Crevasses: they open where the ice is stretched over steeper or faster ground, and the most dangerous are those hidden beneath a thin bridge of drifted snow.

What is a moulin?

A meltwater shaft in a glacier: the name is French for 'mill', and the water it swallows can reach the bed far below, where it helps the ice slide.

Isolated pinnacles of ice left where the cracks in a glacier's surface intersect are called what?

Seracs: the word is French for a white whey cheese, given because a glacier crowded with these blocks of ice looks like a mass of unpressed curds.

The combined width of a glacier's dark and light ogive bands usually equals what?

Its annual movement: a dark band forms in summer and a light one in winter as ice passes through an icefall, so each pair marks one year's travel and the stripes can be read like tree rings.

What triggers the 'glacial earthquakes' that seismometers around the world can detect?

A giant iceberg breaking off: as the berg capsizes it shoves the glacier's front backwards for a few minutes, a jolt of about magnitude 5 that instruments can pick up across the planet.

What are the two principal processes by which glaciers erode terrain?

Plucking and abrasion: the ice freezes onto loosened blocks of bedrock and tears them out, then drags that rubble along its bed like coarse sandpaper, smoothing and scoring the rock below.

Which sediment turns meltwater rivers milky and many glacial lakes turquoise?

Rock flour: ice drags stones across its bed until both are worn to grains so fine that they stay suspended in the meltwater instead of settling.

Long scratches carved into bedrock by boulders in a moving glacier are called what?

Striations: rock stuck in the glacier's sole turns it into coarse sandpaper, and because the scratches line up with the ice's path, scientists read them to work out which way vanished glaciers flowed.

Large boulders carried far from their source and dropped by a glacier are called what?

Glacial erratics: the name comes from the Latin for wandering, and matching one to its home bedrock shows geologists which way the ice carried it.

What is a moraine formed at the foot of a glacier called?

Terminal: it marks the farthest line the ice front reached, and the islands of Martha's Vineyard and Nantucket are partly built of the one the last ice sheet left off New England.

What are the streamlined, canoe-shaped hills called that glaciers left in swarms across upstate New York?

Drumlins: the name comes from an Irish word for a ridge, and because flowing ice streamlined each one along its own path, scientists read a field of them like a compass for a vanished glacier.

Glaciers turn V-shaped river valleys into valleys shaped like which letter?

U: a river saws only a narrow notch, but a glacier fills the whole valley and grinds its floor and walls together, leaving a flat bottom and steep sides, as in Yosemite Valley.

What is a steep-walled valley carved by a glacier called once the sea has flooded it?

A fjord: because the glacier ground hardest where its ice was thickest, a fjord is usually deepest far inland and shallower at its mouth, the reverse of an ordinary bay.

What is the knife-edged ridge called that is left between two glaciers eating into a mountain back to back?

An arete: the word is French for a fishbone, and where glaciers bite into one peak from several sides, the ridges between them climb to a sharp pyramid like the Matterhorn.

A bedrock knoll smoothed on its up-glacier side and left steep and ragged on the other is what?

A roche moutonnee: the ice ground the upstream face smooth, then froze onto the far side and tore blocks away as it moved on, so the rock's lopsided shape still shows which way the glacier flowed.

What are the small lakes called that form when buried blocks of ice melt in outwash plains?

Kettles: Thoreau's Walden Pond is one, a pit left when a stranded block of glacier ice melted, and the depth he sounded there in 1846 still held when government scientists re-measured it in the 1990s.

Long, sinuous ridges of sand and gravel left by streams under a glacier are called what?

Eskers: they are the beds of rivers that ran through tunnels in the ice, and when the ice walls that served as their banks melted away, the gravel was left standing above the land as a winding ridge.

Wind-blown glacial dust builds up as which crumbly, fertile deposit across parts of the US Midwest?

Loess: the name comes from a German word for 'loose', yet it holds firm in vertical cliffs, and in parts of China people have carved cave homes into it.

Glaciers around the world have retreated substantially since the end of which period, around 1850?

The Little Ice Age: in its coldest centuries Alpine glaciers pushed down their valleys and overran farms and villages, so the ice that has been shrinking since about 1850 started from an unusual high point.

In 2019, which country held a memorial service for Okjökull, a glacier that had been declared dead?

Iceland: five years after the ice was declared dead, mourners climbed the volcano Ok and fixed a plaque to the bare rock where the glacier used to be.

Why are Ladakh's ice stupas built as cones?

To melt slowly: a cone of ice shows little surface to the sun for the water it holds, so these artificial glaciers last into spring and release water just as farmers need it for sowing.

Air bubbles in ice cores show that ice ages came and went for 800,000 years in step with which gas?

Carbon dioxide: each layer of ice sealed in bubbles of the air of its day, so a core works as a sample book of ancient atmospheres, with the gas low in every ice age and high in every warm spell.

Why is the land in parts of Scandinavia still slowly rising today?

Its ice sheet has gone: the crust sagged under the weight of ice up to two miles thick, and thousands of years after the melt it is still slowly springing back towards its old level.

Crowds gather in which country to watch the Perito Moreno Glacier's ice dam give way?

Argentina: the glacier's front pushes across a narrow arm of a lake and dams it, the trapped water rises, and from time to time it punches through the ice in a collapse people travel far to see.

In the 2020s, Africa's last glaciers sat on Mount Kenya, the Rwenzoris and which peak?

Kilimanjaro: its ice is the shrunken remnant of a sheet that once covered the whole summit, and a 2022 UNESCO study judged that every glacier left in Africa will very likely be gone by 2050.

What stains the ice red at Blood Falls, on a glacier in Antarctica's Dry Valleys?

Rusting iron: the water is ancient seawater, sealed beneath the glacier for millions of years, and the iron dissolved in it turns red once it meets the air.

On Mars, mid-latitude glaciers lose ice solely by which process?

Sublimation: in air that thin, ice turns straight to vapour without melting, and the glaciers an orbiter's radar found there in 2008 have survived only under protective blankets of rocky debris.

New Horizons found glacial flows of which ice around the Sputnik Planitia basin on Pluto in 2015?

Nitrogen ice: soft enough to flow in Pluto's deep cold, it streams down from the uplands like a glacier on Earth and appears to carry hills thought to be water ice, which is far more rigid there and would float on it.

Jakobshavn Isbræ, long one of the world's fastest-flowing glaciers, drains part of the ice sheet on which island?

Greenland: NASA found in 2019 that the glacier, after twenty years as the island's fastest, had slowed sharply and even thickened once a nearby ocean current turned colder.

While most of the world's glaciers shrank during the twentieth century, what was Alaska's huge Hubbard Glacier doing?

Advancing: it has twice pushed across the mouth of a long sea inlet, in 1986 and 2002, sealing it into a rising lake until each dam of ice and rubble gave way.

In the early 2020s, Indonesia's Puncak Jaya held the last glaciers on which tropical island?

New Guinea: the ice lay close to the equator, kept alive only by the sheer height of the peak, and it was shrinking so fast that it was not expected to last long.

Yosemite's Bridalveil Fall pours from which kind of valley, left by a small side glacier?

A hanging valley: the side glacier could not cut as deep as the main one, so its floor was left high on the wall and its stream now drops out as a waterfall.

Which famous American landmark is a granite boulder that a glacier dropped about 20,000 years ago?

Plymouth Rock is a chunk of Dedham Granite that the ice hauled to the Massachusetts coast, long before tradition made it the Pilgrims' landing spot of 1620.

Which famous waterfall formed only when glaciers melted back at the end of the last ice age?

Niagara Falls first poured over a cliff about 11 kilometres downstream, and has been eating its way back up the gorge ever since the ice left.

Glaciers and ice sheets hold about two-thirds of Earth's fresh water; what holds most of the rest?

Groundwater holds about 30 percent of the world's fresh water, which leaves every lake, river and swamp on the surface sharing well under one percent.

Retreating glaciers on Italy's Marmolada sometimes give up the remains of soldiers from which war?

World War I ran its front line across Marmolada, where Austro-Hungarian troops were quartered in deep tunnels bored into the glacier itself.

What turns patches of summer snow on glaciers pink, a sight hikers have nicknamed watermelon snow?

Algae that thrive in freezing water carry a red pigment alongside their green chlorophyll, and Aristotle was among the first to write about the pink snow they cause.

The Khumbu Icefall, crossed on ropes and ladders, lies just above the base camp of which mountain?

Everest climbers on the South Col route count the icefall among the most dangerous stretches of the whole ascent, and it is at its worst from mid-afternoon.

Franz Josef Glacier, named after an Austrian emperor, descends almost to sea level in which country?

New Zealand's Franz Josef Glacier was named in 1865 by the German geologist Julius von Haast, and it drops to about 300 metres above the sea in just 11 kilometres.

Which waters, holding a fifth of Earth's surface fresh water, sit in basins gouged by ice sheets?

The Great Lakes began to fill about 14,000 years ago, when the retreating ice uncovered the hollows it had dug and the melting ice poured in.

Which small creatures live their whole lives in glaciers and fall apart if warmed to 5 °C?

Ice worms are real, and scientists disagree on how they get about: some say they slip through tiny cracks, others that they melt a path with a kind of antifreeze.

Which Gothic novel stages a tense mountain meeting on the Mer de Glace glacier above Chamonix?

Frankenstein brings Victor face to face with his creature on the Mer de Glace, a river of ice about 7.5 kilometres long and 200 metres deep.

Which naturalist, later a Harvard professor, argued in 1837 that an ice age had once gripped Earth?

Louis Agassiz studied the Aar Glacier from a hut built on the ice itself, and a boulder from that glacier's debris serves as his gravestone.

With water locked up in ice-age glaciers, which land bridge let people walk from Siberia to Alaska?

Beringia was up to 1,000 kilometres wide at its greatest extent, and was named in 1937 after Vitus Bering, who had sailed into the strait two centuries earlier.

Which Antarctic glacier's threat to sea levels led reporters to nickname it the Doomsday Glacier?

Thwaites Glacier holds enough ice to lift the oceans by about 65 centimetres on its own, though the alarming nickname is controversial among scientists.

Which Atlantic coast landmark is largely a heap of debris left at the edge of an ice sheet?

Cape Cod is mostly moraine and outwash that the last ice sheet dumped along its edge, and the ice had melted back past the Cape by about 18,000 years ago.

Which volcano near Seattle is the most heavily glaciated peak in the contiguous United States?

Mount Rainier carries more glacier ice than any other peak in the lower 48 states, and that adds to its danger: an eruption could send enormous mudflows down the rivers that drain it.

Which Alaskan city has the 13-mile-long Mendenhall Glacier just 12 miles from its downtown?

Juneau's glacier has pulled back well over a mile since 1929, the year the lake that visitors look across to see it first formed at its foot.

Geologists class glacier ice, formed from snow squeezed and recrystallised, as which type of rock?

Metamorphic rock is the technical label, because thousands of snowflakes recrystallise under the load above them into far larger, denser crystals of the mineral ice.

What do geologists call a sharp, pyramid-shaped peak that glaciers have carved from several sides?

A horn takes shape when glaciers on different flanks of one mountain eat backwards toward each other, and the Matterhorn is the classic four-faced example.

What have workers draped over part of the Rhône Glacier in summer to slow its melting?

White fleece blankets that resist ultraviolet light cover about two hectares of the ice, where tourists have come since 1870 to walk through a blue grotto.

Which country gave the Fedchenko Glacier, 77 kilometres of ice in the Pamirs, the name Vanch-Yakh?

Tajikistan dropped the name of Alexei Fedchenko in 2023 as part of a derussification drive; he was a Russian explorer who had not even discovered the glacier.

Which South American country's Andes hold around 70 percent of all the world's tropical glaciers?

Peru has Andes that stand higher overall than the ranges farther north, which is why so much ice survives there so close to the equator.

Jostedalsbreen, the largest glacier in continental Europe, lies in the west of which country?

Norway's record holder is kept alive by heavy snowfall rather than by deep cold, and its ice is about 600 metres thick at the deepest point.

Which country's highest summit lost its title as the glacier capping Kebnekaise's south peak shrank?

Sweden saw the ice-topped south peak sink by 24 metres in about 50 years, which handed the record to the bare rock of the north peak along the ridge.

Which country, long thought to have no glaciers, had its first recognised in the Hida Mountains?

Japan had its first glaciers recognised in 2012, on Mount Tate and Mount Tsurugi, where the wet Hokuriku climate dumps very heavy snowfalls on the high peaks.

Ice-age floods from a burst glacial lake carved the Channeled Scablands across which US state?

Washington was swept by more than 40 cataclysmic floods, each one unleashed when a vast lake broke through the dam of ice that had been holding it back.

Which name, coined in 1992, describes ancient glaciations that may have reached the equator?

Snowball Earth was the phrase of the geologist Joseph Kirschvink, and researchers argue over whether a slushy belt of open water survived in the tropics.

Which span of geological time, ending about 11,700 years ago, is known informally as the Ice Age?

The Pleistocene began about 2.58 million years ago, and its name, built from the Greek words for 'most' and 'new', simply means 'newest'.

The Younger Dryas, a sudden cold snap as the last ice age was ending, takes its name from what?

A tundra wildflower called Dryas octopetala thrives only in glacial conditions, so its abundant remains in the sediment show the cold had suddenly come back.

North America's last glacial period, peaking over 20,000 years ago, is named after which US state?

Wisconsin gave its name to an advance that erased the landscape left by the earlier Illinoian ice wherever the newer glaciers rode over it.

The Great Aletsch, the largest glacier in the Alps, flows from the Jungfrau region of which country?

Switzerland's biggest glacier is about 23 kilometres long, and the ice and peaks around it were declared a UNESCO World Heritage Site in 2001.

Which region of South America holds two ice fields left over from an ice-age sheet?

Patagonia's southern field is the larger of the pair, and it ranks as the second-largest continuous expanse of ice anywhere outside the polar regions.

Which US state owes its 'Land of 10,000 Lakes' nickname to hollows left behind by ice-age glaciers?

Minnesota was also handed its farm soils by the ice, which spread deep layers of ground-up debris over most of the state as it came and went.

Which New York City landmark is dotted with boulders that a glacier left about 12,000 years ago?

Central Park's designers left the big boulders exactly where the ice had dropped them, and its rock outcrops carry north-south grooves scratched by the glacier.

Which mountain's icefields feed the Bossons Glacier, which tumbles down towards Chamonix?

Mont Blanc sends the Bossons down the largest vertical drop of any glacier in the Alps, and in 1900 its snout reached right to the valley floor.

Which sea passage was cut when an ice-dammed lake burst through a chalk ridge 425,000 years ago?

The Strait of Dover replaced a land bridge that had tied Britain to the Continent, and the plunging water gouged holes 100 metres deep in the seabed.

Which process, driven by water expanding inside cracks, shatters the cliffs above a glacier?

Frost wedging, known to many students as freeze-thaw weathering, works because water gains about nine percent in volume at the moment it freezes.

What do scientists call all of Earth's frozen water, from glaciers and sea ice to frozen ground?

The cryosphere takes its name from the Greek 'kryos', meaning cold, and it counts snow, permafrost and the ice on rivers as well as the polar ice sheets.

Which explorer found Antarctica's Beardmore Glacier in 1908 and named it for his Scottish sponsor?

Ernest Shackleton climbed the glacier onto the polar plateau, opening a route towards the South Pole, then turned back about 180 kilometres short of it.

Rock evidence shows that which present-day desert lay under glaciers about 450 million years ago?

The Sahara sat at polar latitudes at the time, and the heart of the glaciation later shifted across to what is South America.

What do geologists call the unsorted mix of clay, sand and boulders that a glacier leaves behind?

Till hardens over time into a rock called tillite, and matching beds of it on opposite sides of the South Atlantic were early evidence for continental drift.

What is the small mountain lake called that fills a rock bowl scooped out by a vanished glacier?

A tarn takes its name from the Old Norse 'tjörn', a small mountain lake with no streams feeding it, and New York's Lake Tear of the Clouds is one.

Which word describes a glacier like Alaska's Malaspina, which spills out of mountains onto a plain?

Piedmont lobes can be enormous: the Malaspina's is about 65 kilometres wide and covers roughly the same area as the state of Rhode Island.

What do scientists call a sudden flood bursting from a lake dammed by or hidden beneath a glacier?

A jökulhlaup can be set off when volcanic heat melts the underside of the ice, and the word itself translates literally as 'glacial run'.

Utah's Great Salt Lake is the shrunken remnant of which vast body of water from the last ice age?

Bonneville was the largest ice-age lake of the Great Basin, and it lost much of its water in a tremendous flood down the Snake River that probably lasted under a year.

What name is given to the hilly corner of the Upper Midwest that the last ice age's glaciers never covered?

The Driftless Area is named for its lack of drift, the silt, gravel and rock that glaciers left strewn across the land on every side of it.

Which name is given to the yearly light-and-dark bands of mud laid down in glacial lakes?

Varves can be counted like tree rings, a likeness the geologist Gerard De Geer spotted before he built the first chronology from them in Stockholm.

What is the boundary on a glacier called that separates the zone gaining ice from the zone losing it?

The equilibrium line is easier to measure than a glacier's whole budget of ice, so scientists track its altitude as a quick check on the glacier's health.

Which lake, the largest hidden under Antarctica's ice, shares its name with a Russian research base?

Vostok ranks as the 16th largest lake in the world by area, and its water may have been cut off from the surface for 15 to 25 million years.

What are the dense, cold winds called that gravity pulls down off the high ice sheets of Antarctica?

Katabatic winds take their name from the Greek for 'descent', and around Antarctica they push the sea ice offshore to open up stretches of clear water.

Which mathematician worked out how slow shifts in Earth's orbit could set the pace of the ice ages?

Milutin Milanković, a Belgrade professor of applied mathematics, is remembered in the Milankovitch cycles that describe these slow orbital rhythms.