UGA Stratigraphy Lab

The data is in the strata

Lithostratigraphic Overview

The lithostratigraphy of the Ordovician of Nashville Dome has been stable for over 50 years and is summarized in Wilson (1949). Many of these units were originally defined on both lithologic and paleontologic criteria, and as such, are not in accordance with the modern code of stratigraphic nomenclature. However, these units could be redefined purely on lithologic criteria, which would result in no changes in the positions of unit boundaries and which would bring them into agreement with modern concepts of stratigraphic nomenclature. Several of the group names (Eden, Maysville, and Richmond) are currently regarded as North American Stage names, so alternative names for these groups should be proposed.

Almost all of these formational contacts are unconformable, with the except of the Pierce - Ridley, the Hermitage - Bigby/Cannon, and the Fernvale - Mannie. Most of the formations lack formally defined members, with the Carters and the Hermitage being the notable exceptions. Wilson (1949) does mention a number of informally defined facies, which are essentially equivalent to members, within several units. The Bigby-Cannon Limestone includes the Bigby facies, the dove-colored facies, and the Cannon facies. The Catheys Formation contains a shaly facies, a laminated siltstone facies, a granular facies, a clayey dove-colored facies, a nodular facies, and a pale-colored facies. The Leipers Formation includes an argillaceous facies, a granular facies, and a pale-colored facies.