IELTS Academic Reading Practice Test 57

For more than four and a half thousand years, the Great Pyramid of Giza has provoked the same question: how could a society equipped with copper tools, wooden sledges and ropes of plant fibre raise a structure of such size? Built for the pharaoh Khufu, the second king of Egypt's Fourth Dynasty, the pyramid originally stood about 146 metres high, and for well over three thousand years no human-made structure on Earth was taller.

It is usually estimated to contain around 2.3 million blocks of stone, with a combined weight of roughly six million tonnes. Because its builders left no technical manual, explanations have ranged from the sensible to the fantastic. Over recent decades, however, archaeology has replaced much of the speculation with evidence.

The pyramid did not appear from nowhere. About a century earlier, the architect Imhotep had designed a stepped pyramid for King Djoser at Saqqara, essentially a stack of six progressively smaller platforms. Khufu's father, Sneferu, then commissioned at least three pyramids of his own, and the difficulties his builders encountered are still visible. The so-called Bent Pyramid at Dahshur changes angle partway up, apparently because the original slope proved unstable, while the nearby Red Pyramid was given a gentler gradient from the start. By the time work began at Giza, Egyptian engineers had accumulated several generations of practical experience, including a good deal of costly trial and error.

Most of the stone came from very close at hand. The core blocks were cut from limestone quarried on the Giza plateau itself, a short distance south of the pyramid, which kept transport distances small for the bulk of the material. Finer materials travelled much further. The smooth outer casing, nearly all of which was stripped away in later centuries and reused in the buildings of medieval Cairo, consisted of high-quality white limestone from Tura, on the opposite bank of the Nile. The massive granite beams above the burial chamber, some weighing several tens of tonnes, were brought from Aswan, several hundred kilometres to the south. Such loads could realistically have been moved only by river.

Remarkable confirmation of this river traffic emerged in 2013. A French team led by the Egyptologist Pierre Tallet, excavating at Wadi al-Jarf on the Red Sea coast, found the oldest inscribed papyri yet discovered in Egypt. Among them were logbooks kept by an inspector named Merer, who supervised a crew of boatmen late in Khufu's reign. The best-preserved sections record how his team carried white limestone from Tura to Giza, completing two or three round trips in every ten days. The logbooks do not say what the stone was for, but Tallet believes it was most probably intended for the pyramid's casing. They also mention waterways and basins that brought Nile water close to the building site.

That picture is supported by environmental research. In 2022 a team led by the geographer Hader Sheisha analysed pollen preserved in sediment cores drilled into the floodplain east of the Giza plateau. Because certain plants grow only in or beside permanent water, their pollen allowed the researchers to reconstruct the level of a former branch of the Nile over roughly eight thousand years. They concluded that during the reigns of Khufu and his immediate successors the channel stood high enough to serve as a waterway, so that boats laden with stone could approach the foot of the plateau. As the region gradually became drier, the branch shrank, and today no trace of it is visible on the surface.

Once ashore, the blocks had to be dragged. A wall painting in the tomb of Djehutihotep, a provincial governor who lived several centuries after Khufu, shows a colossal statue on a sledge being hauled by rows of men while a figure at the front pours liquid onto the ground. In 2014 physicists at the University of Amsterdam, led by Daniel Bonn, tested the idea with model sledges on trays of sand. They found that adding the right amount of water made the sand stiffer, so that it no longer heaped up in front of the runners, and this greatly reduced the force needed to pull a load. Too much water, however, cancelled the benefit.

How the stones were lifted remains the most contested question. Almost every specialist accepts that ramps were used, but their form is disputed. A single straight ramp would have needed to be enormously long by the final stages, whereas a ramp spiralling around the pyramid would have hidden the corners that surveyors needed to see. Some support for steep ramps came in 2018 from Hatnub, an ancient alabaster quarry, where a British and French team found a ramp flanked by two staircases lined with post holes. Ropes from a loaded sledge were apparently passed around wooden posts, allowing workers to haul blocks up a slope of around 20 per cent. Inscriptions and tool marks indicate that the system dates at least to Khufu's reign.

Finally, who did the work? The Greek historian Herodotus, writing some two thousand years later, claimed that 100,000 men laboured in three-month shifts for twenty years. Excavation points to a smaller and better-organised labour force. In 1990 archaeologists began uncovering the tombs of workers on the plateau, and nearby, the American archaeologist Mark Lehner and his colleagues have excavated a settlement, known today as Heit el-Ghurab, with bakeries, storerooms and long communal buildings. Enormous quantities of cattle, sheep and goat bones show that the workers were well fed, and skeletons with healed fractures suggest that they received medical care. These were not slaves, as was once popularly believed, but organised teams of labourers, many of them probably serving in rotation.

Soil erosion is, in itself, a natural process. Wind and water have always moved particles of earth from one place to another, and on undisturbed land the losses are generally balanced by the slow formation of new soil from weathered rock and decaying organic matter. The difficulty arises when human activity strips away the vegetation that holds soil in place. Topsoil, the thin upper layer containing most of the nutrients and organic material on which crops depend, can then disappear far faster than it is replaced, since the natural formation of even a few centimetres may take centuries. Few episodes illustrate this danger more vividly than the disaster that struck the southern Great Plains of the United States during the 1930s.

The affected region, which included parts of Kansas, Colorado, New Mexico, Oklahoma and Texas, had originally been covered by short-grass prairie. The deep, tangled roots of these grasses anchored the soil and retained moisture through the long dry spells to which the area is prone. From the late nineteenth century onwards, however, settlers arrived in growing numbers, attracted by federal laws that offered land to anyone willing to farm it. The Enlarged Homestead Act of 1909, aimed specifically at drier western lands, doubled the standard grant to 320 acres. Many newcomers also accepted the claim, spread by some promoters, that cultivation would itself bring more rain to the plains, an idea that proved entirely unfounded.

The decisive change came with the First World War and its aftermath. With European production disrupted, wheat prices rose sharply, and farmers on the plains responded by ploughing up millions of acres of grassland. Petrol-powered tractors and mechanical harvesters, which became increasingly affordable during the 1920s, allowed a single family to cultivate far more land than had ever been possible with horses. Then, when wheat prices collapsed at the end of the decade, many farmers tried to make up for their falling income by planting still more. The result was a vast area of exposed, finely broken soil, protected by little more than the stubble left from the previous harvest.

Drought set in during the early 1930s and persisted, with brief interruptions, for most of the decade. Crops failed, the bare fields dried out, and the strong winds that sweep across the plains began lifting the loose soil into the air. The resulting dust storms, which local people called black blizzards, could turn day into night within minutes. In May 1934 one storm carried dust from the plains as far as Chicago, New York and Washington, and some of it settled on ships far out in the Atlantic. The most notorious came on 14 April 1935, a day remembered as Black Sunday, when a towering wall of dust rolled across the region. Shortly afterwards, newspaper reports began referring to the area as the Dust Bowl, a name that stuck.

The human consequences were severe. Dust filled houses, contaminated food and water, and killed livestock, while many people, especially young children and the elderly, developed a respiratory illness known as dust pneumonia. Families who had lost their crops, and often their farms to the banks, abandoned the region. Hundreds of thousands migrated westwards, many of them to California, where they frequently found only poorly paid seasonal work and open hostility from local residents. Their experience was later portrayed in John Steinbeck's 1939 novel The Grapes of Wrath, which did much to shape how the wider American public came to understand the crisis.

The federal response owed a great deal to Hugh Hammond Bennett, a soil scientist who had been warning about erosion for years. In 1933 he was put in charge of a new Soil Erosion Service, and in the spring of 1935, while he was giving evidence to a congressional committee, a dust storm from the plains darkened the sky over Washington, an event he reportedly used to reinforce his argument. Later that month the Soil Conservation Act created the permanent Soil Conservation Service. Its staff showed farmers how to plough along the contours of the land rather than in straight lines, to plant alternating strips of different crops, and to leave stubble in place to bind the soil. Farmers received payments for adopting such methods, and from 1937 locally run conservation districts spread the techniques from farm to farm. Meanwhile, a federal programme planted around 220 million trees in long windbreaks stretching from North Dakota to Texas.

When rain returned at the end of the decade, conditions improved, and the new practices helped to prevent a repetition on the same scale, although severe drought struck the region again in the 1950s. The broader lessons remain relevant. The UN Food and Agriculture Organization estimates that roughly a third of the world's soils are moderately or highly degraded, and erosion is among the most serious threats. Methods such as cover cropping and no-till farming, in which seeds are drilled directly into the residue of the previous crop, are now widely promoted. The Dust Bowl demonstrated that the land's tolerance for mistakes is limited, and that by the time damage becomes obvious it may be too late to prevent it.

When Wikipedia was launched in January 2001 by Jimmy Wales and Larry Sanger, few observers expected it to last. An encyclopedia that anyone could edit, without payment or credentials, seemed to invite vandalism, error and endless dispute. A quarter of a century later, the English-language edition alone contains more than six million articles, and the site ranks among the most visited on the internet. Its success has not settled the question that has followed it from the beginning, however: can it be trusted? My own view is that the question, in that form, is poorly posed. Wikipedia is neither reliable nor unreliable as a whole; its quality varies enormously from one article to the next, and the more useful question is how readers can tell the difference.

The best-known attempt to measure its accuracy appeared in the journal Nature in December 2005. Experts were asked to review pairs of articles on scientific subjects, one taken from Wikipedia and one from Encyclopaedia Britannica. Across 42 pairs, the reviewers identified 162 factual errors, omissions or misleading statements in Wikipedia and 123 in Britannica, while serious errors were equally rare in both. Britannica rejected the study as fundamentally flawed, and its methodology was certainly open to criticism. Yet its central finding, that the gap between a volunteer project and a venerable professional reference work was far narrower than almost anyone had assumed, was difficult to dismiss.

In my view, the explanation lies less in the wisdom of crowds than in the rules that govern the crowd. Wikipedia's editors are expected to write from a neutral point of view, to avoid publishing their own original research and, above all, to support claims with citations to published sources that others can check. These policies mean that a well-developed article is not simply a statement of what its authors believe but a structured summary of what reliable sources say. On popular subjects, where thousands of people are reading and editing, vandalism and obvious mistakes are often reverted within minutes. A widely viewed page thus resembles a document under constant inspection.

The same mechanism, however, accounts for Wikipedia's weaknesses, because scrutiny is unevenly distributed. In 2005 a false biography of the American journalist John Seigenthaler, which suggested he had been involved in the assassinations of John and Robert Kennedy, remained online for about four months before it was corrected. More recently, it emerged in 2022 that a single contributor to the Chinese-language edition had spent years inventing an elaborate medieval Russian history, producing more than two hundred interlinked articles that went largely unchallenged. Such cases are not typical, but they reveal a structural problem: an article that few people read is checked by few people, and an error in an obscure corner may survive for a very long time.

There is also a quieter problem of coverage. Because editors write about what interests them, the encyclopedia reflects the enthusiasms of its contributors, who have long been disproportionately male and based in wealthier countries. Only around a fifth of the biographies on the English site are of women, and some smaller language editions have been shaped by a handful of individuals. In 2020, for instance, it emerged that much of the Scots-language edition had been written by an American teenager with little real knowledge of the language. None of this involves deliberate deception, but it means that what is absent from Wikipedia can mislead almost as much as what is wrong.

For these reasons many teachers and universities tell students not to cite Wikipedia, and I think they are right to do so, though not for the reason usually given. An encyclopedia of any kind is a tertiary source, a summary of other summaries, and serious academic work should rest on the primary research and scholarly analysis on which encyclopedias themselves depend. Forbidding students to read Wikipedia altogether, however, strikes me as both unrealistic and counterproductive. A good article offers precisely what a newcomer to a subject most needs: an overview of its main ideas, its key terminology, and a list of references leading to more authoritative material.

The real difficulty is that most readers do not use Wikipedia in this way. Research on reading behaviour has suggested that only a tiny fraction of visits to an article ever lead to a click on one of its references. The citations that underpin the site's credibility therefore go largely unexamined by the people who rely on it. This matters all the more as Wikipedia's content is absorbed into other systems: its text is used to train artificial intelligence language models and to supply the summaries that search engines display, often with no indication of where the information came from or how well it is supported.

What, then, should a sensible reader do? The answer is to judge each article on its own merits. Signs of quality are not hard to find: a substantial number of citations to reputable publications, a balanced treatment of disputed points, and an editing history involving many contributors. Warning notices placed by editors at the top of a page, flagging missing sources or a lack of neutrality, deserve to be taken seriously. Approached in this way, Wikipedia is an extraordinary resource. Approached as an oracle, it is a hazard, not because its volunteers are careless, but because no source, however carefully maintained, has earned unconditional trust.