每日英語跟讀 Ep.942: Mystery solved: Scientists trace source of Stonehenge boulders 「巨石陣」石材從何而來?科學家解開世紀謎團

· 每日跟讀單元 Daily English

每日英語跟讀 Ep.942: Mystery solved: Scientists trace source of Stonehenge boulders

Stonehenge, a Neolithic wonder in southern England, has vexed historians and archaeologists for centuries with its many mysteries: How was it built? What purpose did it serve? Where did its towering sandstone boulders come from?


That last question may finally have an answer after a study published on July 29 found that most of the giant stones — known as sarsens — seem to share a common origin 25km away in West Woods, an area that teemed with prehistoric activity.


The finding boosts the theory that the megaliths were brought to Stonehenge about the same time: around 2,500 BC, the monument’s second phase of construction, which in turn could be a sign that its builders were from a highly organized society.


The new paper appeared in the journal Science Advances. Lead author David Nash, a professor of physical geography at the University of Brighton, told AFP he and his team had to devise a novel technique to analyze the sarsens, which stand up to 9m tall and weigh as much as 30 tonnes.


They first used portable x-rays to analyze the chemical composition of the rocks, which are 99 percent silica but contain traces of several other elements. “That showed us that most of the stones have a common chemistry, which led us to identify that we’re looking for one main source here,” said Nash.


Next, they examined two core samples from one of the stones that were obtained during restoration work in 1958 but which then went missing until resurfacing in 2018 and 2019, respectively. They performed a more sophisticated analysis on these samples using a mass spectrometry device, which detects a bigger range of elements at a higher precision.


The resulting signature was then compared to 20 possible source sites for these sedimentary rocks, with West Woods, Wiltshire found to be the closest match. Only the 17th century English natural philosopher John Aubrey had previously postulated a link between “Overton Wood,” probably a former name for West Woods, and Stonehenge.


Previous work has found that Stonehenge’s smaller “bluestones” came from Wales, about 200km to the west, and the new study says that they and the sarsens were placed at the same time. “So it must have been an enormous endeavor going on at that time,” said Nash. “Stonehenge is like a convergence of materials being brought in from different places.”


Just how the early Britons were able to transport the boulders weighing up to 30 tonnes a distance of 25km remains unknown — though the prevailing idea is they were dragged along sleds. The site’s significance also remains mysterious. “I think you’re looking at a very organized society there,” added Nash.


The area was also a hive of Early Neolithic activity. It is home to a huge ancient burial site known as a barrow, a large circular earthwork, prehistoric cultivated fields that are now woodland, and a polissoir — a rock used to sharpen ancient stone axes.


Source article: https://www.taipeitimes.com/News/lang/archives/2020/08/09/2003741335



我們剛剛發給你了一封電郵。 請點擊電郵中的鏈接確認你的訂閱。