stratum layer

例句：

1. 1.The geologist studied the layers of the Earth's crust.
   地质学家研究了地球地壳的层次。
2. 2.The scientists found evidence of ancient volcanic activity in the upper stratum layer.
   科学家们在上层地壳层发现了古代火山活动的遗迹。
3. 3.The archaeologists excavated a new layer of sediment from the site.
   考古学家从遗址挖掘出了新的沉积层。