baserock

Noun

uncountable

The layer of hardrock that lies beneath any surface soil, clay, silt, gravel, and/or sedimentary rock.

Japanese Meaning

表層の土壌、粘土、シルト、砂利、および堆積岩の下に存在する硬い岩盤の層

During the survey, engineers discovered a layer of compact baserock just below the topsoil, which limited excavation depth.

調査の際、技術者たちは表土のすぐ下に堅い基盤岩の層を発見し、それが掘削の深さを制限しました。

Sense（1）

The layer of hardrock that lies beneath any surface soil, clay, silt, gravel, and/or sedimentary rock.

The crack extends down to the baserock and up to the dam crest.