English: Seismite interval in the Devonian of Kentucky, USA.

The rocks in this exposure are deformed beds of the Portwood Member, an offshore marine succession of fine-grained siliciclastics at the base of the New Albany Shale / Ohio Shale. Undisturbed bedding occurs above and below the deformed interval. These chaotic beds have been interpreted as seismites - probably more than one episode of seismicity produced them. The ancient earthquakes that deformed these sediments were related to Acadian Orogeny tectonics, and possibly related to known basement faults in this area.

Stratigraphy: lower Portwood Member of the basal New Albany Shale / Ohio Shale (middle Polygnathus varcus zone, Givetian Stage, upper Middle Devonian)

Locality: Waco Cut - roadcut along the northern side of Route 52, ~0.2 miles east of the Route 52-Route 977 intersection at the town of Waco, eastern Madison County, east-central Kentucky, USA (37˚ 44.471’ North latitude, 84˚ 08.566’ West longitude)

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Info. at:

Schieber, J. & R. Lazar (eds.). 2004. Devonian black shales of the eastern U.S. New insights into sedimentology and stratigraphy from the subsurface and outcrops in the Illinois and Appalachian Basins. Field Guide for the 2004 Annual Field Conference of the Great Lakes Section of SEPM. Indiana Geological Survey Open-File Study 04-05. 90 pp.