Some very ancient sediments were no longer recognizable, having been converted to igneous and metamorphic rocks in the course of mountain building.

在造山的过程中，一些非常古老的沉积物已被转化为火成岩和变质岩，已经无法辨认了。

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However, if life once existed in surface environments, it is likely to have left behind a fossil record in ancient sediments now exposed at the surface.

然而，如果生命一旦在地表出现，他很有可能留下化石记录。这个记录可能是古沉积物形式保留在地表。

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Biomarker has a wide application in the research of petroleum geology, such as different types of organics thermal evolution, ancient sediments' environment and so on.

摘要生物标志化合物在石油地质中应用广泛，可应用于源岩有机质类型和古沉积环境评价以及热演化阶段的确定等。

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That was where the motley sediments of ancient Mars were succeeded by layer upon unvarying layer of brownish rock, two miles high.

NEWYORKER: The Martian Chroniclers

"We have not found any ancient objects linked to the context, and because the paintings are on ravine walls and in the rainy season the sediments are washed away, all we have is gravel, " said archaeologist Gustavo Ramirez, from the Mexican National Institute of Anthropology and History (Inah).

BBC: Cave paintings in Mexico: Carvings uncovered in Burgos