キーベッド

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

• この地ち域いきのキーベッドは火か山灰ざんばい層そうで、広こう範はん囲いに追つい跡せきできる。

  The key bed in this area is a volcanic ash layer that can be traced over a wide area.