geological horizon
Noun: A geological horizon is a distinct layer or boundary within a sequence of rock strata. It is characterized by a specific composition, mineral content, or, most importantly, a particular assemblage of fossils. This distinctiveness makes it a key marker for correlating rock layers across different locations and for determining the relative age of the strata (a process known as biostratigraphy).
A geological horizon is used by geologists and paleontologists as a reference plane or marker bed. Its primary function is for dating and correlating sedimentary rock layers. - It serves as a chronostratigraphic marker, meaning it represents a specific moment or short interval in geological time. - The horizon is identified by its unique fossil content or other consistent lithological features.
- Marker Horizon: A geological horizon that is particularly distinctive and widespread, used as a standard reference point. For example, a layer of volcanic ash (a bentonite bed) from a single large eruption can serve as an excellent marker horizon.
- Biohorizon: A type of geological horizon defined primarily by fossil evidence, such as the first appearance or the last appearance (extinction) of a particular fossil species.
- Stratum (n): A single layer of sedimentary rock.
- Bed (n): A stratum or layer of rock, especially when it forms a distinct unit.
- Marker Bed (n): Synonymous with a marker horizon; a particularly recognizable layer.
- Chronohorizon (n): A horizon used specifically for dating.
- Marker bed
- Key bed
- Guide horizon
- Stratigraphic horizon
- Horizon Correlation: The process of matching the same geological horizon in rock outcrops or drill cores from different geographic locations.
- Index Fossil: A fossil species used to identify and date the geological horizon in which it is found.
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a layer of rock with a particular composition (especially of fossils); for dating the stratum
