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The Geologic Map of Kentucky shows the distribution of sedimentary strata totaling as much as 15,000 ft in thickness and ranging in age from Middle Ordovician to Holocene, with minor amounts of Permian intrusive rocks. The seven columnar sections on the map portray the subdivision of the sedimentary sequence into stratigraphic units and graphically indicate the general lithic character of these units. In addition, eight diagrams on the map illustrate complex stratigraphic relationships. A correlation chart of the stratigraphic units used on the map has been published separately (McDowell, 1981).

This section presents descriptive summaries of the stratigraphic units in Kentucky, grouped by system; they were prepared (in most cases) by geologists who have been closely involved in analysis and mapping of the units during the cooperative mapping project. These summaries provide details of lithology, occurrence, and correlation that could not be included on the State geologic map; many of the summaries also discuss origins of the nomenclature, type localities, depositional environments, and regional aspects of the depositional basins and give references to more extensive or detailed published stratigraphic analyses.

The descriptions of the rocks in each subsection are given by map unit as used on the State geologic map. This necessitates combination or division of some formal stratigraphic units, as well as multiple descriptions of a few formations that are shown in different map units in different regions of the State.

The few map units that include systemic boundaries are described primarily under the system to which most of the unit is referred; for example, the New Albany Shale is discussed in the summary of the Devonian.

Continuing studies have resulted in some revisions of the nomenclature used on the geologic map, specifically in the Silurian and Mississippian of eastern Kentucky and the Pennsylvanian of western Kentucky. The descriptions are keyed to the stratigraphic units used on the map, but the revised nomenclature is also presented for comparison and future reference.

Localities mentioned in the descriptions are all in Kentucky unless otherwise indicated. In many cases, reference is made to geographic regions, such as "Inner Bluegrass" or "The Knobs"; these regions are shown in figure 18 and on the physiographic diagram on sheet 1 of the geologic map. In other cases, the descriptions are applied to regional structures, such as the Cincinnati arch or the Cumberland saddle; these are shown in figure 16 of this report. An index to geologic quadrangle maps is given on plate 1. References to features on the geologic map are given according to the sheet on which they occur.

U.S. inch-pound (English) units of measure are used throughout, inasmuch as the field studies and stratigraphic analyses were conducted entirely in those units; however, the columnar sections on the geologic map have thickness figures in metric units as well.

Ordovician System
Silurian System
Devonian System
Mississippian System
Pennsylvanian System
Permian System
Cretaceous System
Quaternary System


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Created 01-09-01
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