a substratum of clay

• 下面的黏土层

a substratum of clay的用法和样例：

例句

1. We also believe that the visible chasm in the adyton may have been a gaping fissure that extended into the layer of clay above the faulted bedrock.
   我们也相信，在阿底顿里看见的裂沟，可能是基岩的裂口延伸到上方的黏土层。