阅读材料
Stonehenge is a prehistoric monument in England that was built several thousand years ago. It consists of a circle of extremely heavy, tall rocks that originally came from locations as far as 250 kilometers away. It is unclear how the enormous stones were transported from their distant original locations. However, archaeologists have several theories about how the rocks arrived at Stonehenge. Boats One theory is that the rocks were moved by a water route. According to this theory, the rocks were mined or dug out from mountains and transported downhill to the sea. They were then loaded onto simple boat carried them first by sea and then along a river toward the Stonehenge. This is supported by evidence that rocks similar to those at Stonehenge were mined in ancient times from mountains near the sea. Rocks from this kind of location would be relatively easy to roll downhill and then transport by water. Platform-and-Ball System Another possibility is that the large rocks were transported using platforms and wooden balls. According to this theory, the large rocks were placed on platforms. Each platform rested on two lines of carved wooden balls. People then pushed the platform, rolling it over the carved balls, all the way to Stonehenge. This idea is supported by an experiment in which archaeology students built their own platform-and-ball system to test the method. It took just seven students to move stones weighing as much as four tons. Glaciers Finally, the builders of Stonehenge may not have needed to transport the rocks very far at all. Nature may have done it for them thousands of years before Stonehenge was built. Some researchers believe that ancient glaciers (ice sheets) moving slowly across the land picked up the rocks hundreds of kilometers away and later deposited then much closer to Stonehenge. This theory is supported by the fact that glaciers have moved large rocks in many other places.
听力材料
Summarize the points made in the lecture, being sure to explain how they challenge the specific points made in the reading passage.
精华内容
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In the lecture, the professor casts doubt on the reading passage’s theories about how the large stones of Stonehenge were transported. While the reading outlines three possible methods, the professor provides counterarguments to each theory, suggesting that they are impractical.
Firstly, the reading claims that the stones could have been transported by water, with rocks being rolled downhill to the sea and then moved by boats. The professor challenges this by pointing out new chemical tests that show many Stonehenge rocks came from a mountain far from the sea. Moving these rocks to the coast would have involved carrying them uphill, which would have been nearly impossible due to the stones' enormous weight.
Secondly, the reading suggests that a platform-and-ball system could have been used to roll the stones over wooden balls. While an experiment showed that students were able to move smaller rocks this way, the professor argues that this method would not work for Stonehenge's heaviest rocks, which weigh up to 40 tons. The professor notes that the weight of these larger stones would cause too much pressure on the wooden balls, preventing them from rolling.
Lastly, the reading proposes that glaciers may have transported the stones close to Stonehenge during the Ice Age. The professor counters this theory by explaining that glaciers tend to drop rocks at various locations along their path, not in one specific place. Since no similar stones have been found between Stonehenge and the quarry where the rocks originated, this weakens the idea that glaciers carried the stones to their final location.
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