Flynn Creek, USA

Abstract

The peculiar nature of this feature in northern Tennessee was first noted as long ago as 1869. For most of the first half of the twentieth century, it was thought to be a Cryptovolcanic structure. However, in 1957 (Conrad et al. 1957), a detailed study suggested that a more likely explanation is that it consists of the highly eroded remnants of an impact crater (Roddy 1968). The primary characteristic noted at that time was the unusual thickness of a layer of shale (the Chattanooga Black Shale) in an area of otherwise more uniform layering (Roddy 1977a, b). Intense brecciation is present, and shatter cones have been recovered from limestone beds near the center of the formation. The brecciated region occupies an elevated central part of the structure and has been likened to the central peaks of the Sierra Madera Structure and of lunar craters (Evenick et al. 2004). Extensive drilling has provided a detailed profile of the underlying structure (Roddy 1979a, b).