Geological Stage

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Stage, Geological


a subdivision of the general stratigraphic scale, subordinate to a geological series. A stage is subdivided into stratigraphic zones. It includes the stratum of rocks that formed in one geological age and corresponds to a definite phase in the geological development of the earth. The chief criterion for the establishment of the size and boundaries of a stage is the findings of biostratigraphic analysis. Most stages identified on the basis of open marine basins correspond to terrestrial subdivisions.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
In the ancient glacier geological stage, plate rockmasses are covered by a very thick glacier, and the dips of the rock layers have a nearly vertical orientation, as shown in Figure 8(a).
Using reconstructions of the temperature and the ocean water composition of the past, the authors estimated the proportion of aragonite and calcite that formed inorganically in the ocean in 85 geological stages across 500 million years.
Extinction rates vary widely between geological stages, he notes.
If he is right, Mars evolved in several distinct geological stages.
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