它们被厚厚的泥沙沉积物所覆盖，并由于化学变化、压力和温度的作用过程，在漫长的时间中变成了我们所知道的石油。

They were covered with huge deposits of mud; and by processes of chemistry, pressure and temperature were changed through long ages into what we know as oil.

youdao

当时，一场突如其来的大地震使得这片湿地下降了15到30英尺（约4.6米到9.1米），泥沙随之奔流而至，沉积物淹埋了一切，所有的树木和植物毁于其中。

That's when an earthquake suddenly lowered the swamp 15 to 30 feet and mud and sand rushed in, covering everything with sediment and killing trees and other plants.

youdao

大陆架上的沉积物几乎都是由陆地上的江河带来的泥沙，而海洋的成分很少。

Almost all the sediments on the continental shelf from the land-based sediment brought by rivers, while the ocean so much as.

youdao