So sediment is transported and then deposited and it forms layers on the Earth's surface over time.

所以沉积物被运输，然后沉积，随着时间的推移，它在地球表面形成了层。

youdao

Both oil and gas are less dense than water, so they generally tend to rise upward through water-saturated rock and sediment.

石油和天然气的密度都比水小，所以二者通常会浮在被水浸泡的岩石和沉积物的表层。

youdao

The shale roof-made of the sediment that destroyed the forest so long ago-is cracking and flaking off now that the coal below it has been removed.

页岩层顶部是由远古时候掩埋森林的沉积物构成。由于埋藏其下的煤已经被挖走，所以这些页岩有开裂和剥落现象。

youdao

Much of the oil has been removed and processed for use, but each time a large amount of oil is taken from the quarry, more seeps up from the sediment below and so the process has to start again.

BBC: Torrey Canyon seabed returns to normal after oil spill

That there are not could be explained by the fact that the accumulation of sediment in most rocks is so slow that the two layers are, in effect, superimposed.

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Nautilus says that it is devising strategies for minimising the environmental impact, by trying to contain any disturbed sediment and leaving parts of the seabed untouched so the mined area can be recolonised by marine life.

BBC: UK Seabed Resources joins deep-ocean mineral-mining rush