noun
rock formation; rock strata; lithological layer
Geological term referring to a layer or sequence of rock. Used in scientific and descriptive contexts.
この地域の岩石層は約1億年前に形成された。
The rock strata in this area were formed about 100 million years ago.
地質学者は岩石層を調査して過去の環境を推定する。
Geologists study rock formations to infer past environments.