The Earth is full of riches. Once people discovered the importance of metals, they quickly found out where to get them from. The first mined metal may have been copper. When mixed with tin, this formed bronze, malleable but strong. Mines were dug and spoils extracted. Copper could be found in many places, but it was first mined in Cyprus. The name ‘copper’ in fact comes from ‘Koprus’, the ancient name of Cyprus. The mining required charcoal and this came from the trees. Once green, the island quickly became deforested and required managed tree harvesting. It has been estimated that every forest in Cyprus was cut down 16 times during this ancient mining era.

Tin is rarer. It can be a byproduct of ‘deep heat’ associated with granite formation. Granite is associated with mountain formation, a deep magma which has lost its heavy elements and contains mainly silicates. It has low density, so rises but tends not to erupt: it solidifies at depth. Hydrothermal circulation moves the tin around and deposits the metal in fissures and veins. In Europe, Cornwall became a major source of tin; it became known in the Mediterranean as the ‘tin islands’. The Bronze age had a volcanic origin.

In the Middle Ages, the German Erzgebirge (‘ore mountain’) became important as a source of metals, including tin but especially silver, needed for making coins. But mining here became destructive and caused widespread pollution. Around 1495, Paul Schneevogel, a Latin school teacher, wrote a book in defence of the environment. He translated the manuscript into Latin (obviously) with as title Iudicium Iovis in valle amenitatis habitum: The Judgement of Jupiter in the Vale of Beauty. In the book, a miner who is digging into sacred mountains is taken to the court of Jupiter, on the accusation of parricide: the attempted murder of Mother Earth. It becomes a case about who owns the rights to the riches of the Earth.

The accuser is Mother Earth herself, with torn clothes. Mercury, acting as her lawyer, tells about the damage that is being done to her, and the disobedience to Jupiter’s law of honouring one’s parents. Various gods come out as witnesses. Bachus complains that mining is destroying his vineyards. Ceres (god of agriculture) echoes this regarding his crops. Faunus, god of forests, tells of the felling of his trees for the coal burners, used in the silver and gold mining. Pluto, god of the underworld, complains that the noise of the mining has made the eternal sleep impossible. Charon, the ferryman carrying people across the river Styx to the land of the dead, says that the underground water is all being used and diverted, and soon the Styx will be too low for him to deliver the deceased souls to the land of Pluto. It is not looking good for the miner.

The miner defends himself vigorously. He argues that Mother Earth is not a true mother but a hostile stepmother, who hides her riches from their rightful heirs and owners. It is his right to explore and to recover those riches. Jupiter refers the case to another judge, Lady Fortuna. In her judgement, “It is man’s destiny to dig the mountains, to dig mines, to cultivate the fields, to trade and to wound the Earth, to reject knowledge, to alarm Pluto, and to seek out veins of metal in streams. But his body is swallowed by the earth, suffocated by bad air, made drunken by wine, overcome by hunger — and he is unaware of these and other dangers are inseparably connected with being human.” Man has the right to use the Earth, but lacks the wisdom to see the consequences. And this was written 500 years ago!

Forward to the year 1956. This was when the UK passed the ‘Clean Air Act’, in response to the scourge of the Great Smog of 1952. Smog from coal burning had been a problem since the 1800’s, and the link between the London fogs and people dying was well known already by 1880. But 1952 pushed it to a new low, with a death toll in excess of 4000. The 1956 act was actually opposed by the government (for economic reasons) but was passed as a private members bill. It required smokeless fuel to reduce the black smoke from chimneys. The Clean Air Act was later strengthened further.

The act had a large impact on the profession of chimney sweepers. This was a trade that had been passed on from father to son (at an early age, probably, as their life expectancy was not high), but after 1956, it ceased as a career. This was a good thing. In the Songs of Innocence (1789) William Blake’s poem ‘The Chimney Sweeper’ tells the story of the children being sent out: “your chimneys I sweep & in soot I sleep”. One of the boys in the poem, Tom Dacre, has curly hair. At this time, curly hair was sometimes seen as a disease, and it was shaved off. The other children try to comfort him by telling him that now his hair won’t get black from the soot. The boy dreams that he is put in a black coffin: “And by came an Angel who had a bright key, And he opened the coffins & set them all free.” It is a sad poem, as in the end nothing changes. Blake’s follow-on poems, Songs of Experience, take a much darker turn and accuses society of ignoring the plight of these children, as benefitters who: “make up a heaven of our misery”. This was no Mary Poppins profession.

The purpose of a chimney is to channel a volatile substance away from its source. To phrase it more correctly but less politically pallatable, chimneys transport undesirable pollution to a height in the air where it becomes someone else’s problem.

And that is what volcanoes do too.

Volcanic chimneys

Look at volcanoes, and you may see chimneys in action. If so, do hold your breath, just in case, as volcanoes, like people, transport bad air through their chimneys. But not everything that looks like a chimney is one – even if a volcano is involved.

The chimney edifice

The biggest volcanic chimney is the volcano itself. It may not look like one, as the base is so much larger than the top, but the purpose is that of a chimney. Volcanoes emit lava, and that is not a substance one would associate with a chimney. But most of the time, what comes out is a column of vapour, interspersed with phases of ashy, black smoke. Volcanoes most definitely are in need of a Clean Air Act. Sadly, volcanoes are not subject to local laws – only to the laws of physics.

The chimney is built by the volcano itself. It consists of ash, cinders, lava – really, whatever the volcano emits that stays on or returns to the ground. This builds a cone rather than a pillar, and from that point of view, a volcano is not a chimney. But inside is a fairly narrow conduit, maybe a few meters across, in which the magma and volatiles travel upward. Seen from the inside, it does appear like a chimney, although you need to allow for the fact that, unlike our chimneys, much of the content is liquid.

But what comes out is nothing like what comes out of human chimneys. Our chimneys emit smoke: particles of soot from the burning of organic materials such as coal or wood. Smoke does not build mountains, although it can (and will) turn surfaces (and longs) black. Volcanoes produce volcanic ash, but this is not organic and is in effect fragmented rock.

Volcanic ash can cover the ground in layers that can be meters (or more!) thick. Smoke will never do that! The ash is also very heavy (it can be as dense as wet sand) and dangerous: the silicate surface of the ash particles is abrasive and causes damage to lungs and engines. And like smoke, it turns off the sun. After an eruption, it can be pitch dark in the middle of the day.

Both humanic and volcanic chimneys produce gasses. Here there is much more similarity. In the best case, both emit water vapour. CO2 is produced by both, although the amount produced by us is far higher than that of volcanoes. (I have to phrase this carefully so it can’t be misquoted by anti-scientists.) There are other serious pollutants: sulphates and their derivatives, both from volcanoes and from our burning of coal, and fluorine and mercury which are emitted by some volcanoes.

Volcanic pipes

Not all these chimneys are visible. The volcanic chimney can be entirely underground. This happens in kimberlite eruptions, or in the closely related lamproite eruptions. These start off very deep, many tens of kilometers (or more), when a batch of deep magma and the entrained materials (most notably diamonds) rushes to the surface, in the process creating a narrow pipe. If it reaches the surface (not always) it will create a small tuff cone. After the singular eruption the magma that stays in the pipe solidifies – the pipe will never be used again, except for the excavation of diamonds. The volcanic pipe is in effect a long stuffed chimney. An example is Udachnaya in Russia, now one of the deepest open mines in the world.

The fairy chimneys of Cappadocia

The previous chimneys are undisputably made by and used by volcanoes. But there are other chimneys in nature, which may have a volcanic source. The most famous of these (by far) are the fairy chimneys of Cappadocia.

A forest of thousands of spires covers the valleys of Göreme National Park in Cappadocia. They are tens of meters tall, in a spectacular scene which relegates the sandstone pillars of Bryce Canyon to an also-ran. Many of the stone pillars have a cap which can be shaped like a triangular hood. They have provided hiding places for people for at least 4000 years, starting with the Hittites, as various groups battled for ownership of the region. Entire subterranean towns, such as Kaymakli, were dug out, as places of refuge. The largest one contains ten floors, reaches 40 meters deep and could house 60,000 people. Some of the most famous of the ancient underground Christian monasteries and rock-hewn churches are here, often with bright interior painting. Elmali Kilise (‘Apple church’) may be the best known of these. The region is now so touristic that the nearby town of Göreme has almost no real inhabitants – everyone you see here is a tourist, staying in one of the 400 hotels.

Cappadocia is in central Turkey, southeast of Ankara. It is a volcanic area, known as the Central Anatolian Volcanic Province. The names of the individual volcanoes may not be widely known. They are now considered extinct but this may be optimistic. There may have been eruptions here as recent as the early holocene. The largest volcano is Mount Erciyes, nearly 4 km high but now deeply eroded. It is 2.5 million years old and is sitting inside a 100km³ caldera. Erciyes’ most recent eruption was roughly 100,000 years ago. It is one of the volcanoes responsible for Cappadocia’s ignimbrites which form a 1-km thick plateau covering the region. Another one is Mount Hasan.

The famous chimneys were formed by erosion. Like the dwellings inside them, they were carved out from the soft volcanic ejecta of the ignimbrites. The main ignimbrite layers are some 2-2.5 million years old. The ignimbrites became covered with lava flows, which form a much harder rock which protected the softer tuff below against the rain. But wherever the top layer became eroded, the softer rock quickly followed. The remaining fragments of the ancient lava still protect the ignimbrite, forming a roofed pillar. Not all were used for housing: the pillars in the Valley of Imagination lack caves but are known for their surreal shapes.

Erosion pillars are known as ‘hoodoos’ in North America. They can form in several different ways. In Bryce Canyon, they formed in sandstone. But none of those hoodoos can match the volcanic fairy chimneys of Cappadocia.

Penitentes

These rock hoodoos have an unexpected counterpart. Similar structures can form from snow! At their best, snow hoodoos form meters-high structures which from a distance look like a crowd of kneeling people. That gave rise to their name: they are called ‘penitentes’. They are known from the high Atacama desert in South America, where they are found mainly above 4 km altitude. The thin side points towards the Sun, showing that the erosion that forms them in their case comes from sunshine: the structures come from sublimation of the snow in the dry air.

Penitentes are not intrinsically volcanic. But volcanoes can provide the right environment for them to form. They are found for example on the summit of Mount Rainier. Perhaps they are a way for the volcano to say sorry for any damage it has caused! But don’t expect a change of behaviour. This is the penitence of a criminal who was caught.

Snow chimneys

But there are chimneys made from snow which are entirely volcanic in nature. Snow and volcanic heat are not natural companions. It takes special and rather extreme circumstances for them to collaborate. Antarctica will do nicely.

Snow chimneys are found on Mount Erebus, Ross Island, Antarctica. Erebus is famous for its combination of ice and fire; 3.7 km tall, active, and deeply covered in eternal snow, Mount Erebus (god of darkness) is the ultimate ice volcano. It is not the highest volcano in Antarctica: that is the rather less known Mount Sidley. Erebus hosts a long-lasting lava lake, officially discovered in 1972 but probably present since at least the 1840’s. Around the 500-meter wide cone and lava lake is a 3-km wide plateau, an old caldera. This plateau is an active geothermal area with fumaroles.

The geothermal activity in combination with the chilly location has given rise to spectacular features. Think of it as underfloor heating in the freezer. The hot air emitted by the geothermal ground contains various gasses and steam. The heat melts caves in the snow. These snow caves are found at several Antarctic volcanoes but are most famous from Erebus. They require temperatures below -10C year-round. The circulation of air keeps the warm fumarolic air away from the cold sides of the cave. The temperatures become quite balmy and can reach 25C. The thin snow roof lets in sunlight, and as a result life has taken hold. Close to the vent live some thermophilic creatures but further away more common life forms appear, albeit endemic to these caves: mosses, algae, arthropods and nematodes. It is a fragile ecosystem: a change in volcanic activity can collapse or freeze the cave and life has to find another refuge.

As the warm air circulates, it escapes through holes into the outside air. Here, the warm, moist air enters the Antarctic freezer. The temperature plummets, the moisture condenses and turns to snow. Around the fumaroles, a chimney of snow builds up. As the chimney grows higher, it bends with the wind. These are the famous snow chimneys of the Erebus plateau. They are out of this world: volcanic conduits encased in snow. It is the kind of chimney that Tom Dacre might have dreamed about.

Black smokers

And in the final step-in-time of the chimneys, we move from the white chimneys of the high Antarctic to the black chimneys of the deep ocean. These are the black smokers. The name is not entirely justified as they are not black and do not emit smoke, but that is a detail.

Black smokers are deep-water fumaroles. They are found in volcanic regions, and are often associated with mid-ocean ridges. Underground, the volcanic heat meets the wet rock and the heated water begins to circulate. On the way it picks up a variety of minerals. Once it reaches the ocean floor (from below) the hot water enters the frigid ocean. But it doesn’t turn to vapour or steam. At this depth, neither can exist and what comes out is a different kind of liquid, supercritical, superheated and ten times less dense than water. Being low density, it quickly rises. The dissolved minerals precipitate out and the precipitate particles make the rising column opaque to the lights of the human explorers. It looks like a rising black cloud – hence the name.

The precipitates build up rock columns. These are thin chimneys, surrounding the black cloud which still comes spewing out from the top or sides. The largest known black-smoker chimney is 45 meters tall! As in the ice caves of Erebus, life finds a refuge here. Many unique creatures live here, often found nowhere else on Earth. Each has a preferred temperature and therefore sticks to a specific distance from the smoker. These are the oases of the oceans.

And this brings us back to the start of the post. These volcanic regions tap into the mantle, and bring up the minerals found there. It is not just volcanic ash: the precipitates include sulfur, iron, copper and zinc, gold and silver. Some (like copper) are quite toxic to life, in fact. These smokers build up ore deposits. The copper mines of Cyprus have their origin in the deep sea. For this part of Cyprus is an old ocean floor, which was scraped off during subduction and ended up on top of the continent rather than below.

The chimneys of the mines of ancient Cyprus, for which all forests on the island were cut down, were the reflection of the black smokers of the Mediterranean. What goes round comes round.

And this ends the story of the volcanic chimneys of the world. Chimneys transport undesirable pollution to a height in the air where it becomes someone else’s problem. Or their opportunity.

Albert, October 2025