An iridium-enriched sediment layer and a large impact crater in the Yucatn provide evidence that a large meteorite struck Earth about 65 million years ago.

尤卡坦半岛上富含铱的沉积层和一个巨大的陨石坑提供了证据，证明了约6500万年前，一颗大型陨石撞击了地球。

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This sediment layer is enriched in the rare metal iridium and other elements that are relatively abundant in a meteorite but very rare in the crust of Earth.

这一沉积层富含稀有金属铱，以及其他在陨石中较丰富而在地壳中十分罕见的元素。

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The explosion lifted about 100 trillion tons of dust into the atmosphere, as can be determined by measuring the thickness of the sediment layer formed when this dust settled to the surface.

这次爆炸将大约100万亿吨的尘埃提升到大气中，这一数字可以通过测量这些尘埃降落到地表时所形成的沉积层的厚度来确定。

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The sediment layer would have to be less than a km (half a mile) thick in order to have the observed effect, and would probably cover only patches of the outer core.

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To preserve them for more than a billion years to make fossils out of ephemera a site first has to coat its remains in a fixative: a thin layer of waterproof sediment that will slowly harden into stone.

NEWYORKER: The Martian Chroniclers

In the deep water, large swaths of Wilcox sediment slumped over the side of the continental shelf and were swallowed by a layer of salt that dates back to when the American continents pulled away from Europe and Africa.

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