微生物形成的沉积构造 Microbial Induced Sedimentary Structure
海洋沉积物中浮游生物的这种变化标志着白垩纪和第三纪的分界线。
This change in plankton found in marine deposits is what marks the boundary between the Cretaceous and the Tertiary.
在更新世和更早的海洋沉积物中埋藏的化石生物属于孔虫类生物，它们是微小的单细胞海洋生物，其分泌的硬壳由碳酸钙和方解石组成。
The fossils buried in Pleistocene and earlier ocean sediments were of foraminifera—small, single-celled marine organisms that secrete shells of calcium carbonate, or calcite.
在石膏层上方和下方的沉积物中含有许多小型海洋生物化石，这表明这里的海洋环境很开放。
Sediment above and below the gypsum layer contained tiny marine fossils, indicating open-ocean conditions.
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