Key bed


Key bed

In geology, a key bed ("syn" marker bed) is a widespread sedimentary layer that formed at a single time, such that it is useful for geologic correlations and dating over a large area. Examples of key beds are massive ashfalls, such as those produced by nearby normal volcanic eruptions, and far away in supervolcanic eruptions, as well as tills deposited by continental glaciers, and the global iridium layer deposited at the K–T boundary.

ee also

*Radiometric dating
*Relative dating
*Stratigraphy

References

*Stanley, Steven M. Earth System History. New York: W.H. Freeman and Company, 1999. ISBN 0-7167-2882-6 pp. 170-1


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  • Key bed — Key Key (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place …   The Collaborative International Dictionary of English

  • key bed — noun geology : a distinctive stratum or group of strata that serves to facilitate correlation in field mapping or subsurface studies : the horizon or bed on which elevations are taken or to which elevations are referred in making a structure… …   Useful english dictionary

  • Key — (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place. [1913… …   The Collaborative International Dictionary of English

  • Key bolt — Key Key (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place …   The Collaborative International Dictionary of English

  • Key bugle — Key Key (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place …   The Collaborative International Dictionary of English

  • key fruit — Key Key (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place …   The Collaborative International Dictionary of English

  • Key of a country — Key Key (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place …   The Collaborative International Dictionary of English

  • Key of a position — Key Key (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place …   The Collaborative International Dictionary of English

  • Key seat — Key Key (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place …   The Collaborative International Dictionary of English

  • key seat — Key Key (k[=e]), n. [OE. keye, key, kay, AS. c[ae]g.] 1. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place …   The Collaborative International Dictionary of English