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So he visited the site the following year, becoming only the second geologist known to have done so, and took some samples.
因此，他在第二年访问了该地点，成为了唯二这样做的地质学家，并采集了一些样本。
Examining the surrounding cliffs for signs of a collapse, he noticed that a peak known as Annapurna IV offered a relatively smooth, steep face which seemed to fit.
在检查周围的悬崖是否有崩塌的迹象时，他注意到一个被称为安纳普尔纳四峰的山峰有一个相对光滑、陡峭的表面，适合采样。
Back home, he sent samples from the rubble field, the rock core and others from the path the landslide might have taken for dating.
回到家后，他把从碎石场、岩心和滑坡可能经过的路径上采集的样本送去进行年代测定。
Should their ages roughly correspond, that would suggest they were linked to the same event.
如果它们的年代大概一致，那就表明他们与同一事件有关。
By measuring the abundance of chlorine-36 (a radioactive isotope which accumulates in surface rocks and decays once they are buried), and carbon-14 (another which accumulates in living matter and decays after death), his colleagues dated the samples to the late 12th century, and to within a couple of decades of each other.
通过测量氯-36(一种放射性同位素，在地表岩石中积累，一旦被掩埋就会衰变)和碳-14(另一种放射性同位素，在生物物质中积累，在生物死后会衰变)的丰度，他的同事们将这些样本的年代定在了12世纪晚期，彼此相差不到几十年。
That is within the accuracy limits of the dating techniques themselves.
这在年代测定技术本身的精度范围内。
Besides shedding light on a previously unknown cataclysm, Dr Lave’s work could plug a gap in the dominant explanation for why mountains stop growing, which is known as the “glacial buzzsaw” hypothesis.
除了揭示之前未知的大灾难之外，拉维博士的工作还可以填补关于山脉停止生长的解释空白处，即众所周知的“冰川电锯”假说。
Under this model, it is glaciers, which are extremely effective at carving scoops out of mountains, that are mostly responsible for curbing their growth.
在这个模型下，冰川是抑制山脉生长的主要原因，因为冰川能极其有效地在山脉上锯出铲状的空隙。
The problem with that theory, says Dr Rowan, is that there are some peaks that manage to escape the erosive effect of glaciers, and then grow so steeply that glaciers can no longer stick to their sides.
罗文博士说，这一理论的问题在于，有些山峰能够逃脱冰川的侵蚀作用，然后变得非常陡峭，以至于冰川再也不能粘在它们的两侧。
“The question is,” she asks, “what stops these mountains getting bigger?”
“问题是，”她问道，“是什么阻止了这些山脉变得更大?”
Landslides could well be one answer.
山体滑坡很可能是一个答案。
While the exact trigger for the Annapurna landslide is unknown, Dr Lave’s idea is that, with nothing to shave rock off their tips, very high mountains simply keep growing until their weight is too much for their lower slopes—which do still experience erosion—to support.
虽然引发安纳普尔纳山崩的确切原因尚不清楚，但拉维博士的想法是，由于没有任何东西可以刮掉山尖上的岩石，非常高的山脉只会继续生长，直到它们的重量超过了它们的较低的斜坡——它们仍然会受到侵蚀——无法支撑。
Working out exactly how and when the tipping point is reached will require examining other such rockslides.
要想确切地知道如何以及何时达到临界点的话，还需要研究其他类似的岩崩。
Unfortunately, due to the actions of both glaciers and swollen rivers during the monsoon season, the rubble from the Annapurna landslip is vanishing fast.
不幸的是，由于季风季节冰川和河流暴涨的作用，安纳普尔纳山崩的碎石正在迅速消失。
Dr Lave reckons that only about 10% of the dislodged material now remains in place.
拉维博士估计，现在只有被移走物质大约10%的碎石还留在原地。
Older rockslides, assuming there were any, may already be impossible to reconstruct.
更早的滑坡，假设存在过的话，可能已经无法重建了。
