1. n. [Geology]

In sequence stratigraphy, a section of fine-grained sedimentary rocks that accumulated slowly, thereby representing a considerable span of time by only a thin layer. In condensed sections, fossils and organic, phosphatic and glauconitic material tend to be concentrated compared with rapidly deposited sections that contain few fossils. Condensed sections are most commonly deposited during transgressions. In such cases they are associated with "maximum flooding surfaces" and form important sequence stratigraphic markers.

See: glauconite,  maximum flooding surface,  regression,  transgression