Boundary clay layers are used by scientists to determine the rate at which an extinct species declined.

边界粘土层被科学家用来确定一个灭绝物种衰落的速度。

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Other reliable evidence suggests that the deposition of the boundary clay could not have taken one million years.

其他可靠的证据表明，边界粘土的沉积不可能需要100万年。

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However, other reliable evidence suggests that the deposition of the boundary clay could not have taken one million years.

然而其他可靠的证据则表明沉积这层粘土可能不需要一百万年。

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