stratum

rock strataRock strata near Depot Beach, New South Wales, Austl.

stratum, sedimentary rock layer bounded by two stratification planes, the latter being produced by visible changes in the grain size, texture, or other diagnostic features of the rocks above and below the plane. A stratum that is less than one centimetre (0.4 inch) in thickness is termed a lamina, whereas one greater than this thickness is a bed. See stratification.

This article was most recently revised and updated by Amy Tikkanen.
Citation Information
Article Title: stratum
Website Name: Encyclopaedia Britannica
Publisher: Encyclopaedia Britannica, Inc.
Date Published: 18 February 2010
Access Date: February 22, 2025