A relatively thin, continuous stratigraphic succession that encompasses a considerable time span and has reasonable geographic extent. Usually a deep marine section of hemipelagic and pelagic sediments deposited far from the coastline (distal). Generally, it is very fine grain and rich in both number and diversity of fossils, and hence is useful for age dating. Often the distal part of a maximum flooding surface (q.v.) and the top of a transgressive system tract (q.v.). See also Figure S-32.