noun
stratum; geological layer; bed
Refers to a layer of rock, soil, or sediment in the earth's crust. Used in geology, archaeology, and civil engineering.
この崖にはいくつもの地層が見える。
Several strata are visible in this cliff.
地層の年代を調べるためにボーリング調査が行われた。
Boring surveys were conducted to determine the age of the geological layers.