subsoil

名词 subsoil:

1. the layer of soil between the topsoil and bedrock
   同义词：undersoil

1. A specific layer of soil or subsoil in a vertical cross section of land.
   地层，岩层处于土地的垂直横截面中的某一具体土层或次土层
2. Permanently frozen subsoil, occurring throughout the Polar Regions and locally in perennially frigid areas.
   永冻土永久冰冻的下层土壤，出现在整个北极地区和部分长期寒冷的地区