also: けんそう
noun
key bed; marker bed
Geological term for a distinctive, widespread rock layer used as a reference for stratigraphic correlation.
火山灰の鍵層を使って、地層の年代を対比した。
We correlated the ages of the strata using a volcanic ash key bed.
この地域では、鍵層となる凝灰岩層
In this region, a tuff layer that serves as a key bed is widely distributed.
Compound of 鍵 (key) and 層 (layer, stratum), literally 'key layer'. The term is a direct calque from English 'key bed'.