noun
key bed; marker bed
Geological term for a distinctive, widespread rock layer used as a reference for stratigraphic correlation. Also known as 鍵層 (かぎそう) in Japanese.
See also: 鍵層
この地域のキーベッドは火山灰層で、広範囲に追跡できる。
The key bed in this area is a volcanic ash layer that can be traced over a wide area.