So if burning forests didn't create the K-T boundary soot, what did?

K-T分界线灰烬的不是燃烧的森林，那又是什么呢？

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Then, in 1991, researchers discovered a 120-mile-wide, 1.5-mile-deep crater called Chicxulub in Mexico of the same age as the K-T boundary.

随后，在1991年，研究人员在墨西哥发现了与K-T界限在同年代的一个直径120英里宽，1.5英里深的陨石坑，被称为Chicxulub。

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Keller stressed these findings do not deny that an impact occurred around the K-T boundary, and noted that one or possibly several impacts may have had a hand in the mass extinction.

凯勒强调，这些调查结果并不否认，影响发生周围K - T边界，并指出，其中一个或几个可能的影响都有可能在大量物种灭绝中起作用。

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The question is one of the most hotly contested in palaeontology and revolves around an apparent gap in the fossil record immediately prior to the K-T boundary - the distinct layer of geological sediments separating the Cretaceous and Tertiary periods, and associated with a massive asteroid impact and global extinction event.

BBC: Closing the 'three metre gap'