Then something strange happened: the loess in the terraces wasn't on top of crushed rock anymore - it was on top of very finely laminated clay-rich sediments.

然后一些很奇怪的事儿发生了：梯田里的黄土不再在碎岩石上-在非常完美层压的黏土丰富的沉积物上。

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The high-quality source rocks of the lower formation of Es_3, usually with laminated structure, are primarily composed of carbonate laminas and clay laminas with rich organic matter.

沙三段下部优质烃源岩常常呈纹层结构，主要由富有机质的碳酸盐纹层和粘土纹层组成。

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