The Elgin marbles

International controversies can seem intractable. This particular one is about history set in stone. The Elgin marbles were the decorating sculptures of the Parthenon of ancient Athens. The Earl of Elgin (Thomas Bruce), ambassador to the Ottoman empire, acquired them in the early 1800’s. The acquisition had doubtful legality, although opinions differ on this. The Earl’s aim was to use them in his garden in the UK, so that artists could come and draw them from the originals rather than from imagination. Originally he had planned to make casts of the sculptures and take those, but it turned out to be easier to just take the originals, not just from the debris (the Parthenon was in very poor condition at the time, after gun powder stored there had blown up) but also from the parts of the monument still standing. One of the ships which transported the treasures sank on the way – luckily the cargo could be recovered. Elgin later went bankrupt, which allowed the British Museum to acquire them from his estate. The Elgin marbes still remain one of the prize possessions of the British Museum. Obviously, Greece would like them back! Public opinion in the UK is largely in favour of some form of return or shared ownership, but the museum is reluctant and the government not supportive. Trying to solve this seems to be a form of Sisyphean diplomacy. In the mean time, three times as many people see them in the British Museum each year than visit the Parthenon itself!

The Parthenon temple was originally part of the cult of the goddess Athena, although its precise role in this cult is not known. Athena, also known as Pallas, was the protector of Athens and is part of the founding myth of the city.

Elgin properly recognized the sculptures as supreme works of art. Good art makes us see things in a different light: it changes the way we view the world around us. The sculptures did this by connecting the magnificence of the building on the Acropolis with the mythology and history of old Athens. They gave purpose to the building and connected it to Athena. The Elgin marbles do not have the same impact when shown separate from the place where they belong. One may wonder though how long they would have survived in situ. If Elgin had not taken them, would there have been anything left by now? Even Stonehenge only just escaped the damage of the past, making it to the era where we began to protect rather than destroy our heritage. (Perhaps back in 1800 the Greeks should have taken its stones, to protect Stonehenge from the English.) The Elgin Marbles are part of Greek living history. But it was not important to the Ottoman empire as it wasn’t their history. So they sold them.

Greek culture is integrated in the thought patterns of the western world. The Parthenon is a world heritage site for good reason. Cultures can transcend borders, and the culture of ancient Greece has become a foundation stone of the modern world. It is embedded in our language, where so many of our expressions come from ancient Greece, ranging from Cloud Cuckoo land (the mythical fantasy land between humanity and the gods) to Pandora’s Box (with the precious gifts for which we were not ready). We are told to beware of Greeks bearing gifts (especially large horses) – but those gifts included the immaterial treasures of democracy and science, which are now under attack in our modern world. Although much of our social fabric stems from the Near East, much of our thinking is from Greece.

Without the visible connection to the Parthenon itself, the English created another connection in the Elgin marbles. To them, the stoneworks reflected the magnificence of the natural world. This was the time of Romanticism, which was looking to nature as an anti-dote to the insecurity of a rapidly changing society. Keats commented on how the Elgin marbles resembled the mountains from which they came, by their sheer size (or weight) and their physical deterioration:

On Seeing the Elgin Marbles

My spirit is too weak – mortality
Weighs heavily on me like unwilling sleep,
And each imagined pinnacle and steep
Of godlike hardship tells me I must die
Like a sick eagle looking at the sky.
Yet ’tis a gentle luxury to weep
That I have not the cloudy winds to keep
Fresh for the opening of the morning’s eye.
Such dim-conceiv’d glories of the brain
Bring round the heart an undescribable feud;
So do these wonders a most dizzy pain,
That mingles Grecian grandeur with the rude
Wasting of old time – with a billowy main –
A sun – a shadow of a magnitude.

John Keats

The Elgin marbles connected us to an ancient world, a world of stone and water. They contain an echo of a sea, but it is not a sea we know today. This is a story of another world, from which our world descended. The Elgin marbles belong to the Earth.

Marble

Our word ‘marble’, unsurprisingly, has Greek origins. It comes from the word ‘mármaros’, meaning shining or sparkling. The ancient Greeks were fond of marble and used it often. White marble was a particular favourite – and this was not just in Greece: the Taj Mahal in India and the Supreme Court in the USA are largely built from white marble, taken respectively from Makrana in the northwest of India and Vermont. Much later, the word marble became in use for a children’s game involving small white balls made of glass porcelain or indeed of marble, which could be won or lost – and losing them was a major embarrassment. These games were still popular when I went to school and I had my experiences of winning or losing my marbles. In the late 1800’s it became a synonym for losing once’s wits.

Marble is a much hardened version of limestone. It still remains relatively soft, and is easy to cut and polish. Marble comes in a variety of colours. Red to yellow colours may be caused by iron impurities. Serpentine impurities can make marble appear green. Even where these are absent, there may still be grey stripes in the white marble: these come from layers of clay in the original limestone.

Limestone is mainly made from calcite, CaCO₃, deposited in shallow, warm marine waters. It is mostly of biological origin, the debris of marine organisms in need of the security of shells and skeletons. A coral reef is a limestone in the making. But it can also form non-biologically in hot springs, as for instance in Badab-e Surt in Iran.

The process of turning limestone into marble involves heat. The transformation to marble happens when the limestone becomes deeply buried and is subjected to the heat and pressure underground. A heat of several 100 C is required, but the heat should not be so much that the limestone melts. It is called the glass transition temperature, and indeed the limestone becomes glass-like. It crystallises, and these crystals create the marble.

The heat can also happen less deep, when magma comes into contact with the limestone. It happens mainly where tectonic plates collide. (‘Tectonic’ is another word that comes from Greek) The metamorphism (from ‘meta’ and ‘morph’, both Greek) can occur in various environments, but marble requires that either oceanic (a Greek word) or sedimentary (Latin rather than Greek) crust is involved. The limestone needed water.

Mount Pentelikon

The main source of white marble in ancient Greece was Mount Pentelikon. The mountain lies between Athens and the Bay of Marathon. Even though it is some 15 km northeast of Athens, the suburbs of Athens now almost surround it. The mountain is about 1100 meters high, and the southern slopes are covered in quarries, both ancient and more recent. On Mount Pentelikon, the ancient Greeks clearly followed the famous advice from the oracle of Delphi, to leave no stone unturned. Nowadays the region is protected and Delphi’s advice itself has been overturned. The marmer can be used for repairs to the Acropolis but for nothing else.

The marble from here was used for the first Parthenon, build around 490BC, and then for the current Parthenon, an upgrade which was build some 50 years later. In Roman times, marble from Mount Pentelikon was used throughout the empire. There were 162 different quarries on Mount Pentelikon, following three main marble units. All three are located on the southern slope, in three long linear lines each running southwest to northeast up the mountain. The northern-most line contains more recent quarries: the ancient quarries are the lower two lines.

The rocks taken from different quarries have slightly different isotopic ratios of carbon and oxygen. The marble of the Parthenon itself has not been examined for these, but the Elgin marbles have. They show a slight enrichment in ¹³C and a larger depletion in ¹⁸O. Although that pattern is found throughout the Pentelikon marble, the specific ratios are all present only in unit 3, the southernmost of the three lines. At least some of the Elgin marbles were made from stones from the uppermost quarry of unit 3. That is surprising, since the stone work for the Parthenon itself is thought to have been quarried much lower on the mountain.

Marble in general can show a wide range of isotopic ratios. It depends on the source of the original limestone. Limestone from fresh water tends to be depleted in ¹³C, the heavy form of carbon, while deep sea limestones are enriched in ¹⁸O, a heavy form of oxygen. The ratios found for the Elgin Marbles are opposite to this, and are more typical for some corals and red algae. The limestone came from a shallow, warm sea. Long after, there was subduction and heat, and a transformation into marble. Later still, they ended up on the top of a mountain. It was a geological journey, a local expression of events that affected a much wider world. An ocean was born – and died.

The Cyclades

East of Mount Pentelikon and the Bay of Marathon lies the Aegean Sea. Underneath this sea lies a submarine plateau, which is dotted with smaller and some larger islands. These are called the Cyclades. There are over 2000 islands but only the largest ones are inhabited. Santorini may be the best known of the inhabited Cyclades. The sea here is only 100 to 200 meter deep and in fact during the ice age the eastern part was one large island. During the bronze age, the civilization here already produced marble statues which were traded far and wide. The marble came from several of the Cylades, especially: Tinos, Naxos, Paros and Delos. Mount Pentelikon is at the far end of this marble belt which stretches west to east across the islands. Clearly, the Cyclades are at the heart of our story.

The Cyclades are a region of thinned continental crust, only 22-24 km thick. This lack of depth of crust causes the region to lie a bit deeper, deep enough that the platform has become submerged by the shallow Aegean sea. What caused this region to sink? Why are the Cyclades islands and not mountains?

Subduction and the arc

Two of the islands of the Cyclades are volcanic: Milos and Santorini. The latter is only a shadow of itself, having blown up rather spectacularly 3500 years ago, in an event that caused widespread destruction around the Aegean. There have been many small eruptions in the crater since. A surprisingly large (and underrated) explosion occurred in 1650 at Kolumbo, several kilometers from Santorini. It left 200-meter deep deposits, and caused a 20-meter high tsunami: it was in a way an early Hunga Tonga. The Kolumbo eruption was triggered by a flank failure. In contrast to Santorini, the other volanic island, Milos, has not erupted in the Holocene (the last eruption is dated to 90,000 years ago). However, it has geothermal activity. The nearby small island of Antimilos is also volcanic with eruptions dated to 300,000 years ago but appears extinct. There are actually far more volcanic domes in the volcanic arc, but those are hidden below sea level. Three such domes are east of Antimilos; many more are located in the area of Santorini.

The volcanic arc is powered by a subducting plate which at the location of Santorini and Milos lies 130-150 km below the surface. The subduction involves the oceanic crust of the Ionian sea, south of Greece, which belongs to the African plate. The Hellenic trench where the subduction occurs (or has occured) is located south of Crete. Tartarus’ trench is subducting northward, and it has pushed up an arc of islands, of which Crete is the major one – as usual, this region immediately in front of the subduction trench has no volcanism. South of the Crete arc lies a subsidence basin, and south of that is the volcanic arc. The Cyclades beyond this arc are not volcanic.

There is some doubt about the current state of this subduction. The oceanic plate may be experiencing roll-back, with the actual sinking of the plate now occurring further south, at the lower red line in the figure. A new subduction zone is forming here, and the region of the Ionian sea in between the two subduction zones will eventually change allegiance and become part of Europe. In the battles of the plates, the borders are grey zones, not to be trusted.

Everything to the north of the current trench is being pulled southward in response to the rollback. This pull has turned the Aegean Sea into a zone of extension. The rapid movement has caused the crust here to stretch and thin. (With a slight cultural detour, think thin-crust pizza.) As already mentioned, this thinning is why the Aegean Sea has become a sea – there was insufficient depth of crust left to keep it afloat.

Speaking of changeable borders, the Aegean Sea used to be part of the Eurasian plate. But this has changed in recent (geologically speaking) years. The North Anatolian fault in Turkey started extending into the northern Aegean Sea a few million years ago. In consequence, the Aegean sea plate south of this fault has been disconnected form its parent and has become its own microplate. That has affected the movement. The stretching and thinning occured while the plate was still connected to the mainland. Now it can move as a block, so that the crust no longer needs to stretch any further. At the moment the Aegean Sea plate is moving southwest, pushed by Turkey moving west and pulled south by the roll-back of the African oceanic plate. This movement is not shared with the rest of Greece, which is now fairly stationary.

The Hellenic trench connects to one in the Adriatic Sea. Here, there is northeastward subduction of the Adriatic sea underneath the Balkan. An African connection is not obvious since the Adriatic sea has no connection with Africa. But things are more complicated and the borders wars are at times more like insurrections. There are bits of Africa in places where this would not be expected, deep inside Europe and far from the battle front. The ancient Greeks would have understood: their nation is Europe’s Achilles heel. Africa has been sending Europe gifts of land and sea, each a Trojan horse. And Europe has been taking them in.

The mountains of Greece

The current phase of the collision between Africa and Europe, south of Greece, began some 25 million years ago. It has come to a cross road: the Ionian Sea is almost gone and soon the collision will involve the continental crust of Africa. At that time, we can expect a new mountain range to form along the southern limits of Greece.

But there are mountains already in Greece. The high mountains including the home of the gods, Olympus, are in the west, near the Adriatic sea. How did they form? It turns out, there is a long history here of mountain building, and it has to do with the origins of Europe. But it is complex, multi-phased, and the geology has presented a Gordian knot, near impossible to entangle.

Let’s start at the end, the present. As mentioned, the Mediterranean south of Greece has been subducting underneath Europe. This is pushing up a ridge just in front of where the subduction occurs. Crete is on this ridge. But as the subduction is rolling backward, a new push-up ridge has been growing on the seafloor of the Mediterranean itself. It is called the East Mediterranean Chain in the map above but it is also known as the Mesogean ridge. (The term Mesogean comes from the name of the current Mediterranean oceanic plate.) The on-going collision has therefore already built two ridges, as well as the volcanic arc of Santorini, over the past 25 million years ago.

But this was just the last phase of events that go much further back. Before the Mesogean plate was the Apulian plate. This was a small continental plate, moving northward into Europe. It slammed into Greece and Italy, being pulled in by a subduction zone. In front of the Apulian plate was another oceanic plate, and this subducted underneath western Greece. It brought melt and heat but it was not active enough to form a volcanic arc. Apart from that, this was very similar to the Mesogean events, although more to the west. In both cases, the heat largely stayed in pockets underground, each pocket pushing up a small mountain above them. These elevations became the Cyclades, each island a separate heat pocket. The heat reached a few hundred degrees underneath. There was some granite formation but there was not enough for major melt. However, there was enough heat the metamorph the buried limestone and create marble. This happened 45 million years ago and again around 10 million years ago – in Greece, history repeats itself. (The idea of eternal return, that the same events will happen again and again, was part of the Greek philosophy of stoicism.) Thus, the Elgin marbles have a lost oceanic plate or two to thank for their source material.

The Apulian plate arrived, eradicating the ocean in front. It formed a mountain chain at the collision front, and docked. And it is still there. Nowadays the Apulian plate is better known as the Adriatic plate: it lies west of Greece, along the entire Italian east coast, and includes much of the Italian coastal regions themselves as well as part of Slovenia and all of Malta. The mountains on the eastern side of the Adriatic, including western Greece, formed in this collision.

The Apulian plate also had an African heritage: it had split off from Africa and journeyed across, with an older sea in front and a young one behind. This was how the current Mediterranean (the Mesogean) was created.

The subduction of the older ocean and the subsequent collision with the continental plate both formed mountains – the mountains of Greece and the Adriatic thus formed in two phases. It is complicated. And it is old: the Apulian collision was 45 million years ago, whilst the preceding subduction happened more than 60 million years ago.

But the Apulian was not the first lonesome traveller on their odyssey to Europe, blown across on the winds of Aeolus. Long before the Apulian plate was the Cimmerian plate. This too had been part of Africa, and like Apulian after it, it eradicated an ocean before it and formed a new one behind it. This plate took a more easterly route – it docked, and stayed, making its home in Eurasia. The name ‘Cimmerian’ is taken from a small mountain range in Ukraine, along the southern coast of Crimea.

The Cimmerian plate formed parts of northern Turkey as well as Greece. This plate brought us the Cyclades region itself. The Cyclades too were immigrants. And again there were mountains that formed, this time along a wide region to the east.

And so plate after plate had come and joined, and the mountains they formed were on the land donated by the previous arrivals. The Cimmerian plate has seen mountains growing on its own land from collisions with the oceans and plates that followed. Mount Olympus, home of the Gods, is a gift from Africa. The Herculean task of building it and the other Hellenic mountains was carried out mainly by workers from Africa.

The Elgin marbles and Mount Pentelikon have a long history. The original limestone was brought by Cimmeria. It was deposited in a warm shallow coral sea, on the continental shelf of Cimmeria, to become part of Europe between 200 and 150 million years ago. The Apulian plate and the subduction that preceded and followed its arrival changed the region. Pockets of heat transformed the limestone and created marble. The heat also caused mounts to rise. Over time, erosion took hold and eventually the buried metamorphosed limestone came to the surface – ready for marble mining.

East to west and south to north

Take a look at a map of the world. There are two long chains of mountains. One runs north-south along the western side of the Americas and into Antarctica. The other is not as easily recognized, is older and appears less joined-up. It runs from the Pyrenees in Spain through the Alps, the Caucasus, the Hindu Kush and the Himalayas to find its terminus in southern China. It consists of many different ranges and they don’t alwasy connect well. In some places they even run double. But the chain is unmistakable and everywhere. Why is it here?

Now take a look at Europe and Africa. All over southern Europe are short mountain ranges, including in places far from Africa. In northern Africa, there are no such mountains: the land is old and eroded. The only exception is in Morocco, which looks like, geologically speaking, it belongs to southern Europe. The titanic collisions between Africa and Europe have left scars are all over Europe – but not in Africa. Why is that?

The answer is, of course, that the collisions have not been between Africa and Europe. It was done by migrations. Pieces of Africa came off, drifted across, and collided. Europe, on the other hand, has not done the same in return. It received but did not reciprocate. The process is still continuing. In the past 30 million years, Africa has lost Arabia, part of its Craton heart. (Kratos, of course, was yet another Greek god, son of Athena.) That is now moving north and will soon collide headlong with Iran. In the process it is also pushing Turkey west, into Greece. It is a geological and political nightmare, inviting the Greek god of Chaos. But apparently, all this has happened many times before. The siren call of the north was irresistible.

Drifting fragments of continents need oceans to drift in. This is also a story of that ocean.

The Tethys ocean

The battle indeed had been Titanic. The ocean was called the Tethys, and Tethys was a daughter of the Titans. Her parents were the Titans Gaia and Uranus (not the most obvious combination) and she was married to the Titan and river god Oceanus – so ‘Tethys Ocean’ refers to the couple. (Oceanus was also her brother – Greek mythology was a soap opera of dubious morality.) They had thousands of children – one for each river in the world.

Oceanus was the god of a river that went around the entire world. The Tethys ocean was a sea stretching from China westward to America. There is indeed a similarity between them. Perhaps a more appropriate name for the Tethys would have been the Oceanus ocean! (This might however invite a conflict with Poseidon. It is complicated.)

The story of the Tethys starts with Pangea, 400 million years ago. All the continents had come together into a single supercontinent. (Only one small village still held out against the Pangeans…) There was a small indentation in the Pangea coast line, near to where China is now. That indentation was a sign of trouble to come, but is hard to recognise as a danger on the map. The curse of Cassandra was that no one would believe her prophecies of disaster. The indentation became larger and developed into a bay and later a sea and eventually an ocean (no – not a river). The southern shores drifted away and became their own world. Gondwana was born.

The ocean eventually split the supercontinent east to west, extending as far as the ocean basin of the Gulf of Mexico. It was an equatorial ocean, tropically warm and full of life. It was the ultimate coral sea, at least on the northern shores. Gondwana drifted too far and became colder. Seeing the error of its ways, it stopped and started to reverse course, back towards the warmth of the equator. (‘To blow hot and cold’ is another expression from ancient Greek mythology.)

What actually happened is that the new ocean had become an old ocean and old ocean floors sink and subduct back into the underworld, Hades. The spreading ridge that formed the ocean would have been located close to Gondwana, so the ocean floor there was young and buoyant. The oldest oceanic crust was next to the northern shores. Subduction developed along this coast: it began to close the ocean and pull in Gondwana. At this time the Tethys ocean was still extending westward through several branches. One of those branches would find the rifts of the proto-Atlantic, and through these connect as far as the Gulf of Mexico. This completed the division of Pangea into Gondwana and Laurasia, while the Tethys ocean was already beginning to close in the east.

As Gondwana odysseyed back north, new rift zones developed further south. These east-west rifts occurred inside Gondwana and resulted in Gondwana fragmenting. A large fragment, or perhaps a series of pieces, left and crossed the ocean ahead of the rest. This became Cimmeria. It joined Laurasia, and added new land, stretching from Greece to Malaysia. Turkey, Iran, Tibet and many other places were born as Gondwanan refugees. It is an enormous region: this was not just a sliver of land, it was a continent by itself. But whether it came in one piece or in pieces is not known.

Behind Cimmeria, a new ocean formed. Nowadays we call the first ocean the Paleotethys and the new one the Neotethys. The latter is also just called the Tethys ocean. The ocean received a new floor and a new name but otherwise remained the same.

Events took place and history was made. At times the world, like Icarus, flew too close to the Sun. The Siberian traps which nearly wiped out life on Earth happened just north of the Paleotethys ocean, at about the time Cimmeria separated from Gondwana. The million years of rain drenched the shores and started both the age of the dinosaurs and that of the mammals. Much later, the Deccan traps occured in the Neotethys ocean. The Chicxulub  impact happened on its shores. But even this ecological disaster led to a new and richer world. At times, the narrow western arm of the ocean ran out of oxygen, and the huge sediments of tropical organic matter were unable to decay. This organic matter became buried and metamorphed to black gold: it formed the oil of the Middle East. So much of our society depends on the produce of the Tethys. Later, India crossed the Tethys and joined Asia, pushing up the Himalayas. This started off the southern Asia monsoon, the rains that feed much of our world. Only Australia is still holding out as the Gondwana survivor, but it too is on the way to rejoin the north.

The Tethys ocean had the Midas touch. The biggest disasters turned to new riches: everything it touched turned to gold. Greece escaped the particular riches of the black gold, but this is just sour grapes (an expression from the tales of Aesop). Instead it ended up with the purest white marble. Tethys is the gift that keeps on giving.

Greek gifts that last

Is anything left of the Tethys ocean itself? Apparently, John of Patmos who lived on one of the Cyclades islands, did not think so: he wrote that ‘the sea was no more’. But this is disputed. Sometimes the Black Sea is considered a Tethys remnant, a part of perhaps the Paleotethys that did not quite close. But it was never an integral part of the Tethys. The Gulf of Mexico is also a survivor from the days of the Tethys ocean and it was connected to it. But it has its own history.

The Mediterranean sea is often considered the remnant of the Tethys. But it is not the same as the ocean that there was before: the original Tethys ocean was further north.

Can oceans migrate? When a new oceanic crust forms, is it still the same ocean? The Mediterranean has seen plates come and go. Does it need to be the same water? But the Mediterranean ocean once dried out completely, 5 million years ago, leaving a deep gash in the Earth and an ecological disaster that dwarves that of the Aral Sea. The Earth is like the Titan Cronus, devouring its own children for fear of being surpassed by them.

The Mediterranean is really its own sea: a descendent of Tethys but not the goddess herself. This is a good heritage to have. The children of Tethys included Eurynome, whose children we call the Charites, the goddesses of grace and beauty. Another of her children was Metis, the mother of Athena in whose honour the Parthenon with its marble sculptures were built.

The real remnants of the Tethys ocean are not found in the sea. They are in the mountains that were formed along its northern shores, which often including material from the Tethys and Paleotethys oceans themselves. The life of the Tethys has formed the highest mountain on Earth: the fossils of Mount Everest are such a memory of Tethys. But so is the marble of Mount Pentelikon which formed from the coral reefs of this tropical world ocean.

The Elgin marbles are so much more than just human history. They come from, and belong to, a lost ocean. The Tethys ocean has shaped our world in so many ways. The Elgin marbles are part of its history. They are a Christmas gift from our greatest ocean. Keats saw it well. It mingles Grecian grandeur with the rude wasting of an ancient ocean.

Albert, December 2023

From all of Us to all of You: VC wishes all you readers a Merry Christmas, and a touristic volcanic 2024!

And for the traditional Christmas games

How many numbers do you see?

Spot the circles!

The stable painter