石炭层

例句：

1. 1. The geologist found a layerof fossilized shells in the rock.
   地质学家在岩石中发现了一层化石贝壳。
2. 2. The paleontologists are studyingthe layers of sedimentary rocks to understandthe history of the area.
   古生物学家正在研究沉积岩的层次以了解该地区的历史。
3. 3. The archaeologists excavated a layer of ancient potteryfrom the site.
   考古学家从遗址挖掘出一层古代陶器。