Marker Bed

marker bed

[′märk·ər ‚bed]
(geology)
A stratified unit with distinctive characteristics making it an easily recognized geologic horizon.
A rock layer which accounts for a characteristic portion of a seismic refraction time-distance curve.

Marker Bed

 

a bed in rock strata that is distinctive owing to structure, color, great density, the presence of concretions and fossils, or any other features that make it possible to trace it when correlating sections and preparing geological maps. It differs in principle from the stratigraphic horizon, which is based on a set of organic remains and includes beds of different facies types.

References in periodicals archive ?
This analysis suggests several brachiopod-based bioevents, such as the conspicuous occurrence of micromorphic, mainly thecideoid representotives, which typify a pre-ETMME marker bed in the I-LS.
undulata, distinctive taxon of the north-African margin and, especially, the first record in the Iberian Peninsula of thecideid marker beds prior to the ETMEE.
Cross sections can be fully customized and edited, including reshaping contacts, adding well headers, selecting which layers to visualize, hanging the cross section on a selected reference datum such as mean sea level or a marker bed, and exporting the cross section into Voxler 3 for true 3D visualization.
The recent RC drill program undertaken by QMC in 2010 indicates the gold is controlled primarily by a near E-W trending shear zone developed along the contact between the amphibolite unit (marker bed) and underlying phyllite and schist sequence.
This limestone bed represents an important marker bed at the top of Paleocene and the base of Eocene formations.
The top of the lower section of the Porters Creek Formation is often marked by an indurated, glauconitic siltstone or mudstone that can be used as a marker bed for structural mapping.
The anticlinal interpretation is preferred because the lower Porters Creek siltstone marker bed elevation change is gradual rather than abrupt as would be expected if a fault boundary were crossed.
Bilotte, 1985; Philip and Airaud-Crumiere, 1991; Ross and Skelton, 1993; Barnes et al., 1996), because this bioevent was found in only one section its utility as a marker bed in the basin was limited.
As this bioevent was identified in only one section (Amacuzac) its utility as a marker bed is limited in the basin, where it may have not been observed because of the degree of condensation of the sections.
2), where at the field scale it displays a distinct physical break or "marker bed" of variable thickness, between 10 and 75 cm.
These facts indicate that three of the four marker beds failed quantitative ink constraints in specific ways.
Recent fieldwork has been focused on examining the stratigraphic relationships between fossil localities and laterally continuous geological marker beds in the Great Divide Basin.