Upper Ordivician Sequatchie Fo

Rocks belonging to the Ordovician System are exposed along Interstate 75 between Cleveland and Chattanooga in a road cut in White Oak Mtn or sometimes called Green Gap. These rocks show the upper portion of the Middle Ordovician Catheys Formation and all of the Upper Ordovician Sequatchie Formation including the Fernvale Member. The road cut exposes a section of rock that was measured at two hundred and seventy-five feet. This stratigraphic section was examined in detail …

…the bottom of a lagoon. Unit 5 Unit five is representative of the Fernvale Member of the Sequatchie Formation. Tan and pink calcirudite and cacarenite plus silty gray shale make up the major portion of unit five. This unit is approximately twenty feet thick and consists of eight layers of tan calcirudite. These rocks are shoal deposits or were deposited on a shell bank. Low energy environment is typical of the deposition shown in this unit.