Rome – The Eternal City
Students will begin their exploration of the intersection of geology, geography, and history with the city of Rome itself. This analysis will focus extensively on the most ancient period of Roman history, the semi-mythical period of the Roman Kingdom. The key question in exploring this location will be “what enabled Rome to become the seat of a continent spanning empire?” As Historian Mary Boatwright phrases it, “Rome’s location was a favorable one” thanks to plentiful supplies of clean water, seven hills pressed next to the Tiber River that allowed for easy defense in times of crisis, fertile soils, and the closest point inland from the Mediterranean Sea where the Tiber could be forded.11 During the period of the Roman Kingdom, the Latins expand the influence of the city to Ostia, translated literally to mouth, for both its access to the Mediterranean sea, as well as substantial salt pans, an essential component to preserving food in the ancient world. Rome’s geography and landscape permitted the city to eventually establish dominion over the rest of the Italian peninsula, and later much of Europe.
Understanding Rome’s geographic advantages requires that students and teachers understand the geological factors which brought about Rome’s existence. Through the process of plate tectonics, the African and Eurasian plates collided together forming the backbone of the Italian peninsula’s Apennine Mountain range, and then separated to form the Mediterranean Sea. The Apennines, once submerged, reveal its nautical origins in its lithography, where limestone forms because of the collection of the calcium of seashells and corals. As this process occurred, the Italian Peninsula separated from the whole of mainland Europe, leaving behind as evidence the islands of Corsica and Sardinia. Geologists Grant Heiken, Renato Funicelli, and Donatella de Rita write that “the complex collisions and extension (pulling apart) of the Earth’s crust in this region lasted from about 20 million to 2 million years ago, [while] at the same time, the Italian Peninsula began to rotate counterclockwise, opening basins to form what is now the Tyrrhenian Sea.”12 In part due to Italy’s proximity to major fault lines, the peninsula was host to a substantial amount of both seismic and volcanic activity. Evidence of these volcanos can be found in calderas close to Rome itself, as well as the substantial deposits of tuff, a rock composed of volcanic ash which has lithified into solid material.13 Almost since the city’s founding, Romans made use of tuff, quarrying it extensively as the building blocks for the city’s built environment. These examples show directly how natural history has shaped human history. Looking more closely at Rome’s geology, the city sits on a flood plain of the Tiber River, formed through both tectonic and volcanic processes. The Field of Mars, a large open area where Roman armies would gather and prepare outside of the ancient city’s walls, would frequently flood when the river overflowed. The field served a dual purpose: its natural one, protecting the city from the river’s might; and it's military one, as the mustering ground for the Roman legion. Throughout the unit, students will understand how Rome’s power and might adapted to the natural world. The city’s proximity to the Mediterranean was an obvious advantage, but Rome was primarily a land power, especially in its early years as it united the Italian peninsula under its rule. Essential to the Roman project of power was roadbuilding, and even here we can see a crucial connection to natural history. Efficient road building goes around mountains and tries to follow flat terrain as much as possible. Heiken et al. explain that two of the most important roads of Ancient Rome, one crossing the Apennines and the other extending out into the heel of Italy’s boot, the “Via Flaminia and the Via Appia follow routes along valleys formed by erosion along major faults.”14 Through understanding these connections, students will be able to analyze decisively the effects that geology has on the growth and development of human civilizations.
Figure 1 – Map of Ancient Rome15
Looking forward to the present day, over 3000 continuous human habitation years has had a demonstrable impact on the geology of the city. Rome’s plethora of ancient ruins, most buried underground, are archaeological treasures. But the city’s storied past, on average at least 20m below the current city, has made modern Rome a sinkhole capital of Europe. Since Rome sits on a flood-plain, situated on the Monte Vaticano formation, a loose collection of sedimentary deposits, on top of millennia of construction, excavation, and quarrying, have put modern Romans at risk of sinkholes. Factoring in changes in climate due to climate change increases the risk of flooding, and thus the likelihood of a sinkhole, along with tens of thousands of vehicles driving the city’s streets, means that Rome from 2010 to 2017 saw an average of 90 sinkholes a year.16 A combination of geological and human factors has created the present reality of the city.
Pompeii and Herculaneum – Preserved Moments of Disaster
Ancient Rome bore witness to one of the most well-known moments in geological history, the eruption of Mount Vesuvius. History remembers the names of Pompeii and Herculaneum for their connection to the deadly eruption, as otherwise they would have likely been a footnote in the historical record. This disaster gave contemporary historians an unprecedented examination into daily Roman life, something often lost in written sources, with buildings, artifacts, graffiti, and even the last poses of the victims preserved. The term “volcano” comes from the Romans, as their term for the mountain on an island of the Mediterranean which seemed to billow as the chimney of Vulcan, the god of the forge.17 The gods, heroes of myth, were reflected in the world. Underneath the Palatine Hill, perhaps the heart of power in the city, in the Lupercal cave, the she-wolf weaned Romulus and Remus. So too did Romans see a sort of divine power to the volcano, one they would certainly encounter explosively on an afternoon in August of 79 CE.
The amazing degree of preservation at Pompeii and Herculaneum is due to the type of eruption that devastated the two towns. Most rock that exists in the earth is in fact solid; but magma, or liquified rock, does form under a special set of circumstances, depending on factors such as chemical composition, pressure, and tectonic forces.18 As discussed in the previous section, the Italian peninsula contains active extensional faults, where the Earth system is more likely to produce liquid rock, and consequently, volcanos. Because magma is lighter than the surrounding solid rock underground, it moves up through a chamber in Earth’s crust to reach the surface, eventually erupting from a vent. Vesuvius is a stratovolcano, meaning that its mountainous cone shape has formed due to centuries of eruptions, as solid layers of volcanic rock and ash are piled on top of each other. The eruption of Vesuvius was so violently explosive due to a variety of factors, including the buildup of gases present in the magma under extremely high pressures. The viscous nature of the magma meant that the gases could not escape until reaching the earth’s surface, resulting in a tremendous and destructive blast. Geologists term the specific type of eruption seen in 79 CE as either Plinian, after one of its observers, or Vesuvian, after the volcano itself. The eruption is characterized by a large explosive plume of ash, rock, and gases to heights potentially over 20 km into the atmosphere. Additionally, this type of eruption also includes a swift moving pyroclastic flow, a current of hot tephra (volcanic matter, not necessarily lava) that encased many of the victims in its path.19
Figure 2 - J.M.W. Turner's stunning interpretation of Vesuvius in Eruption20
While Pliny’s description survived, the actual towns of Pompeii and Herculaneum were lost to the historical record and were only rediscovered in the 18th century. What archaeologists discovered over a millennium later buried under the ash was almost a direct step back in time. The towns were comparatively wealthy, with many of the Roman elite building villas to take advantage of the pleasant coast and fertile soils.21 The number of artifacts and data available for historians to use is staggering. Penelope Allison22 goes so far as to record the nature of the rooms in Pompeiian households, the nature of the artifacts found in those homes, considered alongside primary sources from Latin authors. The archaeological record preserved by Vesuvius’s eruption reveals more about daily life for Romans than almost any other source. Graffiti strews the walls, such as those found in the basilica connected directly to the public forum: “I am amazed you haven’t fallen down O wall / loaded as you are with all this scrawl.”23 Some graffiti is the ancient equivalent of the scratchings on the bathroom walls of a bar, equally as crude then as it is today, so care should be taken if examining these texts with students. The miracle is that they survived at all. Most stunning, and terrifying, are the plaster casts made of some of the corpses found scattered throughout the city. During excavations in the 19th century, archaeologists discovered that many of the bodies were posed, with little decay, exactly as they were on the day they died. Using plaster of Paris, the bodies have retained these positions, making the tragedy of the natural disaster feel real and present two thousand years later. With many online resources, artifacts, and images available, Pompeii is an excellent way to have students study material culture and the actual lived experiences of Romans. At the same time, we also build an understanding of the geological processes that brought ruin.
Vesuvius is still an active volcano, and last erupted in 1944. While no other eruptions have been as deadly as the one of 79, the Italian Peninsula still has several active volcanos. Naples, the city closest to Vesuvius, has been affected by its eruptions in the past, and other volcanos pose a very real, and potentially disastrous, danger today. Comparing the present-day population of Naples, numbering almost a million people, to the populations of Pompeii and Herculaneum, about 20,000 people, it is clear the mortality of another such explosive eruption would be far greater. Fortunately, modern science has a far better range of tools to study and understand volcanos. Despite the two thousand years that have since passed, Vesuvius is one of the best studied historical volcanic eruptions, given both the lasting historical and geologic interest that it has, and will likely continue, to generate. As researchers led by Domenico Doronzo concluded, research on Vesuvius “can be applied to many explosive volcanos worldwide, particularly when inhabited areas are directly exposed to eruption impact… as modern architecture could take advantage from what happened in 79 CE.”24 Contemporary research on volcanos can hopefully mitigate the disastrous effects of an eruption so close to a densely populated area. The story of Pompei presents such a rich and deeply interconnected historical and geologic tapestry. This section displays what a tremendous, and indeed devastating, impact the Earth system can have on human history.
London – The Edges of the Roman Frontier
The next stop in our journey across the Roman world takes us to one of the furthest corners of Europe. With our study of Rome, we considered the earlier history of the Roman Kingdom and Republic, while Pompeii and Herculaneum offer glimpses into the early Empire. To understand the Roman project in London, students and teachers must also consider in its larger context the Roman project of Empire. Julius Caesar was the first Roman to take his legions across the English Channel in 55 BCE, writing in boastful third person that “Caesar thought it would be of great service to him if he only entered the island, and saw into the character of the people, and got knowledge of their localities, harbors, and landing-places.”25 In his time, Britain was the furthest frontier of the known world, with an interior that would promise riches. Caesar is perhaps downplaying the reasons for his sojourn into Britain, as the conqueror of Gall did not emerge from that island as the victor. While Caesar could not conquer Britain, he did set precedent for Roman involvement in the British Isles. A little under a century later, with the transition of Rome from Republic to Empire, the Emperor Claudius would try to establish dominion over Britain again. Claudius dispatched four Roman legions led by general Aulus Plautius, and Rome would maintain a (mostly) permanent foothold in the south of Great Britain for over 300 years. With Plautius’s eventual defeat of the Britons, their riches were ripe for plunder by the new conquerors. Roman geographic knowledge of Britain before the invasion was limited; Julius Caesar reported tin, iron, and other mineral riches, land ripe for cultivation, a climate more moderate than Gaul. Interestingly, Caesar does note that its more northerly status results in less daylight. Historian Peter Salway writes that the Romans regarded Britain as “a land of natural abundance and that by AD 47, the exploitation of Britain’s mineral resources—one of the chief objectives of victory—had begun (the silver-bearing lead of the Mendips was being mined under state control by this date)”26 Deposits of natural resources, good soil, and moderate climates are all shaped by geological factors, and imperial dominance is rooted in the quest for material riches. London, a city with a location that was both strategically and economically advantageous, would serve as the seat of the Roman government of Britain, and would itself be the home of an even larger empire over a thousand years later.
Julius Caesar first noted the importance of a location, though not named as London, fits its description. He writes of a place “about eighty miles on the Thames from the sea” where the “river can be forded in one place only and that with difficulty. 27 According to Caesar, the Thames, and this crossing, were both a territorial boundary as well as an important strategic location, as it was here that Caesar fought the Britons under the leadership of the general Cassivellaunus in 55. Caesar and his legionaries saw the tactical advantage of the Thames as an artery to the North Sea. It is unsurprising that the Thames also marked tribal boundaries, as rivers, mountains, and other natural features often define political borders, After the conquest of Britain under Claudius, the Romans established London as the provincial capital. The original Roman colonia of Colchester would be destroyed during the revolt by Queen Boudica, but as Roman historian Tacitus writes, while “not distinguished by the title of colony, [London] was none the less a busy centre, chiefly through its crowd of merchants and stores.”28 Londinium suffered the same destruction as Colchester did during the revolt, with Tacitus describing one resident witnessing a dreadful omen “in the estuary of the Thames…a vision of the ruined colony.”29 That this vision of doom comes in the river speaks to its strategic role in the success and failures of armies. Halting Boudica’s fording of the river was the city’s salvation, failing its destruction. The Roman General Suetonius was unable to muster his forces in defense of the city, and instead retreated, defeating the Queen after she had burned the Roman settlement. The defeat of Boudica gave the Romans a path to take control over the southern portion of Britain, although the Empire would never advance past the wall that the Emperor Hadrian built 70 years later. It is worth noting that many of the Roman colonies were intended as permanent settlements, not merely military outposts or locations to extract and ship off resources (although there was certainly much of that across the Empire). Peter Salway writes, “Rome was unlike most modern empires in that it gradually extended its citizenship to those it absorbed.”30 The Romans saw the city as an anchor to the Romanticization of the British Isles. The archaeological and documentary evidence speaks to both the military and commercial origins of London as a seat of power. The similarities between the locations of Rome and London on inland rivers with navigable access to the ocean are not surprising, as river fords and crossings have key tactical and economic advantages. Historian Lacey Wallace writes that in London the “choice of landscape characteristics, location within existing tribal-political territories, town planning and infrastructure, and planned industrial, commercial, and domestic organization are all significant reflections of how they conceived of the idea of a town, and its significance and purpose to their daily lives.”31 It was the Thames that made London a viable site for settlement and ensured its future. Connections to commercial avenues, freshwater, accessible crossings, access to the North Sea via the Thames, strategic advantages, and available deposits of clay and stone all factored into the choice of London as a seat of power.
Geology will be the key to understanding not only the origins of Roman London, but likewise its rapid growth, and at the heart of our geologic exploration of the city is the Thames. During the last glacial period, roughly 20,000 years ago, lower sea levels meant that the English Channel was not submerged. The Thames connected with other Major European rivers, including the Rhine. The recession of glaciers raised global sea levels, flooding the English Channel, and by about 5000 BCE, the Thames had been fully severed from the European mainland. Just as the Thames can carry ships out to sea, it also deposits large deposits of sediments like sand, clay, and silt along its course, giving definition to the terrain. The British Isles are relatively stable tectonically in contrast to the geologically chaotic Mediterranean. Sedimentary deposits are key to interpreting the city’s lithography. The same chalk that defines the stunning cliffs of Dover can be found beneath surface deposits across the greater London area, allowing access to underground water. The London Clay, a marine sedimentary rock, largely defines the rock formations throughout the city, along with alluvial deposits of sand and silt on the banks of the river. As described by the British Geological Survey, “the original Roman settlement of Londinium was sited on dry sand and gravel deposits close to the River Thames, with readily available water supplies from riverside springs. As the city grew, the abundant water supplies from the major Chalk groundwater aquifer supported the rapid population growth. A ready supply of locally worked aggregate and brick clay deposits aided the infrastructure development.” Water, close access to the river, quarrying, and clay for brick all make London a favorable site for a town, in addition to the Romans’ political and military considerations. 32
The Thames, while a boon to the Roman settlers of Londinium, has presented substantial challenges to Londoners in the millennia since its founding. Greater London is part of the Thames floodplain, so during times of exceptionally high tides or rainfall, the area is vulnerable to potentially deadly and destructive rainfall. As the city’s population grew, the Thames would also become increasingly polluted, with at times the smell of human waste choking the city’s inhabitants. These issues would lead to the creation of innovative (for the 19th century) sewage and drainage systems, but the Industrial Revolution also brought factories and further pollution into the river. Industrialization also brought the burning of fossils fuels and the gradual warming of the planet. The consequences of a changing climate can be seen today, as floods, drought, and potential scarcity of potable water remain present day issues.33 In the 1980s, London officials constructed the Thames Barrier, a system designed to prevent flooding in the city much as Romans had used dikes to stem tidal waters. Now forty years old, the Barrier is being used more and more. At the same time, London is also facing the possibilities of drought. Winter is usually the rainy season in Britain, but the levels of rainfall are increasingly falling short of meeting the needs for water in the summer. Rising air temperatures means water evaporates quicker, while human demand simultaneously rises.
Rio Tinto – Mineral Wealth and Abundance
Our final case study location is the Roman mines of Rio Tinto, located in the Huelva province of Andalucia, noted for their significant deposits of iron, copper, and silver. Resource extraction has occurred here since before the times of the Romans and continues today, and the modern-day town of Minas de Rio Tinto is home to the largest open pit mine in Europe. In this case study, students will understand the impetus that brought the Romans to this part of Spain, and the geological systems that birthed such rich mineral deposits. Originally controlled by Carthage, Rome’s during the Republican Era, the Iberian Peninsula fell to Rome after Carthage’s defeat in the Second Punic War. The region called Andalucia today was named Baetica and was a distinct political province from its northern neighbor Hispania. While the Roman name of the mines and settlement at Rio Tinto have been lost to history, Pliny the Elder, who would perish in the eruption of Vesuvius, described in his Natural Histories that “nearly the whole of Spain abounds in mines of lead, iron, copper, silver, and gold… and in Baetica there is cinnabar [mercury sulfide].”34 Our examination of London revealed that the project of Roman expansion was driven not only by political aims and the absorptions tribes into the Empire, but likewise by the desire for control over mineral wealth. Historian and archaeologist GBD Jones notes that today remnants of over “sixteen million tons of ancient slag [are]ringing the northern edge of the mining area,” evidence that Rio Tinto was one of the most important and prolific mines in the Roman realm.”35 The sheer output of silver was essential to the health of its economy. When Baetica came under threats from foreign invaders in the last second century, documentary evidence showing a decline in mining at Rio Tinto corresponded to similar declines in the circulation of silver coinage across the Empire. Rio Tinto was a key component of the circulation of goods and money across the Empire.36
To extract such tremendous quantities of ores, Romans employed a variety of technologically innovative, though often dangerous, methods to extract and smelt the ores. In addition to the physical act of digging out the tunnels and ensuring adequate lighting and ventilation, flooding often occurs due to both surface and ground water seeping into the lowest chambers. In the 1920s, archaeologists discovered a massive water wheel which could pump water over a height of 30 meters from the lowest levels of the mine (figure 3). The water wheel demonstrates the tremendous amount of human labor required to operate a mine of this scale, which included enslaved labor. Mining was a dangerous task in antiquity, as environmental historian Lukas Thommen writes, “lead poisoning was characteristic” of the Roman mine labor, especially the smelting process, and that the “the contaminated air deposited ever greater amounts of metals in the soils.”37 Mining towns, like the one at Rio Tinto, were never intended to one day flourish as London one day would. The dry and hilly location had little access to clean sources of water as the water of the Rio Tinto would certainly not be potable because of the extensive pollution from the mining operation (see Figure 4 below) and no convenient connections to navigable bodies of water. Rio Tinto served as a point of extraction for the benefit of the imperial project, more on the periphery of the life of the Roman citizen than London. Once the ores were mined and smelted, the challenge remained of how these exceedingly valuable resources could reach the centers of power and commerce.
Figure 3 - The Roman Water Wheel Discovered in Rio Tinto38
The Roman system of roads was the answer to this challenge, a feature that was essential to Rome’s expansion and connection across Europe. Historian M.C. Bishop describes that the soldiers of the Roman legion were often the ones to build the roads, from a strategic perspective. roads made movement and refurbishing supplies far easier. Likewise, legions enabled vast networks of commerce. Bishop further writes that “wherever possible, local materials would have been used…they could be obtained from most river valleys, and quarry pits can often be seen lining roads.”39 Rio Tinto contains remnants of the Roman roads that crossed the Iberian Peninsula, and part of the Roman Empire’s strength was how interconnectedness. In hilly and mountainous terrain, roadbuilding could prove treacherous and difficult, and would require digging trench roads, forming terraces, or simply rerouting to avoid too difficult terrain. As Camilla Campedelli writes “in the Southern regions of the Iberian Peninsula, we can still see the solutions adopted by Roman builders in the development and implementations of the road system in a morphologically intricate territorial context.”40 The Roman road served not only as routes of trade, but also as a form of Imperial power and control. As the saying goes, all roads lead to Rome, and vast material riches to their travelers.
Some Romans recognized the potential dangers of such intensive extractive processes. In his Metamorphoses, the poet Ovid writes of the mythical descent of humankind from the golden and silver ages of tranquility and harmony to the ages of bronze and iron. He writes that “not only did they demand the crops and the food the rich soil owed them, but they entered the bowels of the earth, and excavating brought up the wealth it had concealed in Stygian shade, wealth that incites men to crime. And now harmful iron appeared, and gold more harmful than iron.”41 Ovid primarily identifies the problem here as one of greed, rather than environmental destruction, but still sees something sinister in those things which are best kept beneath the earth. Food, sustenance, all come the soil, identified here as good and nourishing, while destruction and greed are found below. Pliny the Elder condemnation of mining and lust for ore even further:
She [the earth] is continually tortured for her iron, her timber, stone, fire, corn, and is even much more subservient to our luxuries than to our mere support. What indeed she endures on her surface might be tolerated, but we penetrate also into her bowels, digging out the veins of gold and silver, and the ores of copper and lead; we also search for gems and certain small pebbles, driving our trenches to a great depth. We tear out her entrails in order to extract the gems with which we may load our fingers. How many hands are worn down that one little joint may be ornamented! If the infernal regions really existed, certainly these burrows of avarice and luxury would have penetrated into them. And truly we wonder that this same earth should have produced anything noxious! We tear out her entrails in order to extract the gems with which we may load our fingers. How many hands are worn down that one little joint may be ornamented!42
Pliny personifies the earth here, and evoking the same bodily language that Ovid used, and while his language is likewise focused on the consequences of greed, the feeling of the damage that people do to nature feels clawing and real. For Pliny, the earth fights back, and he would indeed come to know the full power of the earth’s might and capacity for harm.
Figure 4 – The Distinctive Orange Hue of the Rio Tinto43
Having considered the Roman practices of mining, we must now turn to the question of how the silver and copper that made Rio Tinto such an attractive place to the Romans ended up there. Jones writes that “it is thought that mineralization occurred in two stages, first when tufaceous sediments along the ridge were impregnated [by volcanic activity] with copperless pyrite. This was followed by probable fracturing and the creation of chalcopyritic, or copper bearing, veins normally occurring vertically. The ores present in the Rio Tinto area are primarily sulfide minerals.” Put simply, ore deposits are largely the result of magmatic activities, and are brought to the Earth’s surface through the processes of plate tectonics. Millions of years ago, as the tectonic plates came together in forming the supercontinent of Pangaea, one plate was, to put it simply, shoved under the other in a process known as subduction. Pockets of magma concentrate the metals, and the rock makes its way to the surface through either tectonic or volcanic activity (recall that volcanos and earthquakes are more likely to form along the lines of active faults).44 Most of the metals that people consider valuable can be found in trace amounts in many rocks, but not at levels high enough to be valuable. Native metals, that is metal that is not bonded to anything chemically, can be found in smaller amounts in nature, but most valuable elements are found in ores -- rocks which contain concentrated amounts of the element, but do require a further physical or chemical concentration process for extraction. In addition to the human pollution caused by mining, and indeed, smelting, the process of heating ores at very high temperature to extract metal content, Rio Tinto is highly acidic with a pH of 1.7 to 2.5 and has notable orange hue because of the concentrations of hematite derived from the weathering of iron pyrite (see Figure 4). Particularly noteworthy, as marine biologist Sarah Bordenstein writes, is that while mining pollution has contributed to the river’s extreme environment, “the presence of chemolithotrophic organisms, such as iron-oxidizing bacteria and sulfur-oxidizing bacteria, are thought to be the true culprits to the river's condition.”45 The acidic nature of the river has given rise to an ecosystem unlike few others on the planet. The collision of geology, biology, and history makes Rio Tinto a place that should spark curiosity while also allowing students multiple pathways to interpreting its significance.
The scale of the mines at Rio Tinto today far exceeds any the Romans could have ever envisioned. Across the globe, we must mine for the metals and minerals that make the chips in our phone, that line the wires that transmit energy, and that enable technologies that have become essential to how we live. The geological and biological processes that made Rio Tinto distinctively rich in minerals, the tremendous lengths that Romans went to harness those metals, the voices of Ovid and Pliny condemning the dangers of extractive greed, all give insight into how people presently make their marks on the planet in pursuit of its resources. As students consider these perspectives, they can understand the processes that shaped our planet and how humans have shaped the planet in turn, in the pursuit of pursuing new solutions to the problems of greed and destruction that mining can have.
