operational unit

An arbitrary stratigraphic unit that is distinguished by objective criteria for some practical purpose. Also known as parastratigraphic unit.

Related terms:

• time-stratigraphic unit
• rock-stratigraphic unit
• rock unit
• lithostratigraphic unit
• lithostratic unit
• lithologic unit
• chronostratigraphic unit
• chronostratic unit
• chronolithologic unit
• time-rock unit