IELTS Academic Reading Practice Test 298

On the flat floodplain of the Mississippi, a few kilometres east of the modern city of St Louis, stand more than a hundred earthen mounds. They are the remains of Cahokia, the largest settlement ever built in North America before Europeans arrived, and for a century or so after about 1050 it was the centre of a society whose trade reached across much of the continent. At its height the city is thought to have housed between ten and twenty thousand people, a population comparable with that of many European towns of the same period. Then, within a few generations, it was empty.

The place itself was not new. People had lived beside this stretch of the river for centuries, but around 1050 the settlement was transformed with unusual speed. Plots were laid out on a regular plan, a vast open space was levelled, and a series of flat-topped platforms rose above the surrounding houses. Archaeologists have found traces of a landscape created in a very short time, which implies that someone already held the authority to gather and feed large numbers of labourers. Why Cahokia expanded so rapidly is disputed, though its position at the junction of great rivers, with fertile soils for maize, clearly helped.

The biggest of the platforms, now known as Monks Mound, is the largest earthen structure in North America. It covers more than five hectares at its base and still rises about thirty metres, though centuries of rain and frost have worn it down. It was built in stages, each adding a fresh layer of clay to the last, and a large building stood on its summit. From the top, a person could look down on the whole city and across the river beyond. The name comes not from the original inhabitants but from a small group of monks who farmed nearby in the early nineteenth century.

In front of Monks Mound lies a rectangular plaza of about twenty hectares, flattened and carefully drained, which probably held markets, ceremonies and ball games. Smaller mounds were grouped around it, many of them burial places or the bases of important buildings. A wooden wall, or palisade, enclosed the central area, and it was rebuilt several times, a fact that some researchers read as evidence of growing insecurity.

Ordinary inhabitants lived in houses of timber and mud plaster with thatched roofs, set in rows along the streets. Excavations have produced maize, beans and squash, together with stone hoes and pottery, but also objects brought from astonishing distances: copper from the Great Lakes, mica from the Appalachian mountains and marine shells from the Gulf of Mexico. Such goods point to trade networks, or to pilgrimages, that linked Cahokia with regions hundreds of kilometres away.

One mound, known simply as Mound 72, has yielded the most striking evidence of the city's rituals. Excavated in the late 1960s, it contained the body of a man laid on a bed of thousands of beads cut from marine shell, arranged to outline a bird with outstretched wings. Close by were the remains of well over a hundred other people, many of them young, whose treatment suggests that they were killed as part of a funeral ceremony. The finds are interpreted with caution, because the mound was excavated quickly and some of the records are incomplete.

A further puzzle is a series of circles traced in the soil by the postholes of tall wooden poles, one of which has been rebuilt on the site. The largest circle held forty-eight posts. Because the positions of several posts line up with the rising sun at the solstices and at the equinox, the circles are generally regarded as calendars or observatories used to mark the agricultural and ceremonial year. They came to light in the 1960s, when a bulldozer preparing ground for a highway scraped away the topsoil.

Why Cahokia declined is even less clear than why it grew. Building work slowed after about 1200 and the population fell. By 1350 the city had been abandoned. Explanations include a series of droughts, the exhaustion of farmland and the felling of the surrounding forest for fuel and timber, which may have led to flooding and erosion. Others point to internal unrest, hinted at by burnt buildings, or to the collapse of the long-distance exchange on which the rulers depended. Most archaeologists now consider that a combination of stresses, rather than a single cause, is likely.

Much of Cahokia has been lost. From the nineteenth century onwards, ploughing, roads and housing destroyed or levelled many of the mounds, and a highway cut through the site in the 1960s. The surviving core became a state historic site, and in 1982 it was added to UNESCO's list of World Heritage sites. Only a fraction of the settlement has been excavated, and large areas remain unexamined beneath fields and gardens. A visitor centre explains the site, but the landscape itself is quiet and gives little away.

The name by which the city is known is itself a reminder of how much has gone. It derives from a people of the Illinois confederacy who were living in the area when French visitors arrived in the seventeenth century, long after the city was empty. Nobody knows what its builders called it.

Few colours in the ancient world were as valuable as Tyrian purple. The dye was produced from sea snails of the murex family, above all Bolinus brandaris, the spiny dye-murex, and Hexaplex trunculus, the banded dye-murex, both common in the eastern Mediterranean. Its association with the Phoenician city of Tyre was so close that the Romans called it purpura Tyria, and the Greek word porphyra came to mean both the colour and the rank it signified. The substance was so expensive that it was sold by weight, and the finest dyed wool was among the costliest goods traded anywhere in the Roman world.

The animals are unremarkable: a spiral shell a few centimetres long, a muscular foot, and a habit of feeding on other shellfish. What made them precious was a small gland near the throat, the hypobranchial gland. In life the secretion is colourless or pale; it is only after the gland has been removed, exposed to air, and treated that it turns purple. The chemistry is unusual. The precursor compounds are brominated indoles, and the final colouring matter, dibromoindigo, is closely related to the indigo of plants.

Pliny the Elder, writing in the first century AD, gives the fullest surviving description of the process. According to his account, the shells were cracked open, the gland taken from the throat, and the tissue salted and left to steep for several days. The mixture was then heated slowly in lead vessels, and the result was tested on wool. Pliny also noted that the strength of the colour depended on the season, the location of the catch and the length of the heating, details that suggest an industry governed by experience rather than by fixed rules.

The work was notoriously unpleasant. The decaying snails and the heated vats produced a stench that ancient writers complained of, and dye works were often placed at the edge of a town or on the shore, away from the main streets. In some cities the workshops were moved outside the walls for this reason, and the odour clung to the clothes of the workers. The smell was apparently accepted as the price of a colour that no other material could imitate.

Archaeologists have recovered the physical traces of this industry. At coastal sites in the eastern Mediterranean, excavations have uncovered thick layers of crushed shells, the debris of generations of dyeing. The heaps are sometimes metres deep, and the shells are often broken in the same place, where the gland was reached. At Tel Shiqmona, on the coast of modern Israel, the deposits were so extensive that they have been used to estimate the scale of production.

One property of the dye puzzled ancient observers. Wool dyed with it could look dull or even yellowish when it was taken from the vat, and only after it had been hung in the sun did the full purple appear. The change is caused by oxidation: exposure to light and air completes the conversion of the precursor compounds into the stable pigment. Buyers were advised to judge the colour in daylight, and the practice of testing a sample in the open air became part of the trade.

Because the dye was costly, it became a marker of status. In Rome, senators wore a tunic with a broad purple stripe, the latus clavus, while the narrower stripe of the equestrians indicated a lower rank. Under the emperors the rules tightened. By the fourth century AD, legislation reserved particular shades of purple for the imperial household, and the right to wear them was granted only as a rare privilege. The colour therefore did two things at once: it displayed wealth, and it advertised proximity to power.

Production declined in the later Byzantine period. The reasons are not fully understood, but several pressures probably combined. The supply of snails was limited, and the cost of fuel for the heating vats rose. Cheaper imitations, made from plants or from a mixture of dyes, took part of the market. Political disruption in the eastern Mediterranean interrupted the trade, and the centre of demand shifted. By the end of the Middle Ages the technique had been largely lost in the region, although a small industry survived for a time elsewhere.

The identity of the colouring compound was established only in 1909. Paul Friedlaender, a German chemist, obtained a quantity of murex snails and extracted the pigment from them. The work was laborious: about 12,000 snails yielded only 1.4 grams of the pure substance. Analysis showed it to be dibromoindigo, a molecule closely related to indigo but containing two atoms of bromine. The result explained both the colour and its stability, and it confirmed what ancient writers had described in practical terms.

In recent decades there have been attempts to recreate the dye. Chemists can synthesise dibromoindigo in the laboratory, and a few craftspeople have returned to the old method of extracting it from living snails. On the Pacific coast of Mexico, dyers still milk the glands of a related species and paint the secretion onto cotton thread, a technique that predates the Spanish conquest. Such enterprises remain small, because the dye is expensive and the snails are slow to harvest. The colour that once marked an emperor is now a curiosity. No modern workshop has matched the scale of the ancient industry, and the colour remains a luxury.

In the centre of Berlin, beside a busy road, stands the broken tower of a church built in the 1890s. Its roof was destroyed in a bombing raid in 1943, and after the war the city decided not to rebuild it. Instead the tower was left standing, its stonework still blackened by fire, and a modern church was built alongside it in the early 1960s. Coventry made a similar choice: the ruins of its medieval cathedral, bombed in November 1940, remain beside the new building consecrated in 1962. In Hiroshima, the shell of a hall that stood near the centre of the 1945 explosion is now a World Heritage site. Other cities took the opposite course.

Warsaw is the best-known example. Its historic centre was destroyed during the Second World War, and after 1945 it was rebuilt, street by street, using old paintings and photographs as guides. Dresden's Frauenkirche, which collapsed after the bombing of February 1945, stood as a ruin for half a century before it was reconstructed; the work was finished in 2005, and original stones were reused where they could be, so that dark patches remain visible in the pale new facade. The choices made in each of these places were shaped by money, politics and the strength of local feeling, but each was also an answer to a single question: what should a city do with the physical evidence of its own suffering?

The argument for keeping ruins is that they are evidence. A rebuilt street can reproduce the shape of what was lost, but it cannot reproduce the fact of its destruction. Conservation architects make this case most strongly: for them the value lies in the material itself, in the charred stone and the twisted metal, and in the decision to leave it alone. A replica, they argue, teaches a visitor nothing about violence, whereas a wall that is still broken is its own explanation.

Those who disagree are usually practical people. Town planners point out that a city cannot be preserved as a museum of its worst day. Ruined buildings are expensive to hold up: stonework has to be pinned, water excluded, and the public kept at a distance for safety. The land they occupy may be the most valuable in the city. Above all, a city that leaves its wounds open may give the impression of a place that has not recovered. Rebuilding, on this view, is not forgetting; it is an act of confidence.

There is a commercial worry too. Preserved ruins attract visitors, and the industry that grows around them can be uncomfortable. Souvenir stalls beside a mass grave, guided tours that promise an authentic experience of terror, and the transformation of a place of grief into a backdrop for photographs: all of these have been observed in cities around the world, and the risk is a genuine argument against turning damage into an attraction.

For the people who lived through the events, the question is often less about buildings than about attention. Survivors' associations in several countries have insisted that commemoration should be centred on the dead and on those who endured the attacks, not on the fabric of the buildings that happened to survive. A carefully stabilised ruin, they note, can overshadow the human story it is supposed to serve. Some residents also object to living beside a permanent reminder of the worst hours of their lives, and in a few places people have asked for a site to be cleared simply so that they can walk past it without being reminded.

Teachers of history take a different view. Many report that a damaged place does something a classroom cannot: it conveys scale and violence directly, and it makes the past feel less like a story and more like an event. A wall with shrapnel marks in it is a document that no textbook can supply.

Museum curators are more cautious. Fragments, they argue, are best brought indoors, where they can be protected from weather and from vandalism and set beside the explanation that makes them intelligible. A ruin left in the open is exposed to everything, and a visitor who comes across it in a street with no caption may simply see a broken wall.

My own view is that both camps are partly right, and that the question has been badly framed. It is not a choice between keeping everything and keeping nothing. No city can preserve every damaged structure; most of the fabric of a bombed district will always be replaced. What matters is selectivity. A small number of sites, chosen for what they can still show, stabilised competently and explained without sentimentality, will do more for memory than a hundred untreated ruins. Interpretation is not decoration; a ruin without context is simply a wreck.

Decisions should also be taken quickly. The cost of making safe a structure that has been left to decay for decades is far higher than the cost of acting while the damage is fresh, and delay usually ends in demolition by default. Where a site is kept, rebuilding around it should be part of the memorial rather than its enemy: the Berlin church and its modern neighbour make a better argument together than either would alone. Keep some traces, then, but choose them deliberately, and tell people what they are looking at.