Breccia and Pennsylvanian cave filling in Mississippian Saint Louis Limestone, Putnam County, Indiana

Abstract

ABSTRACT A limestone breccia and several bodies of shale and sandstone in Mississippian St. Louis Limestone were discovered in a quarry opened during the summer of 1959 in the SE NW sec. 15, T. 15 N., R. 4 W., Putnam County, Indiana. A small mass of sandy limestone conglomerate overlay part of the breccia. Nearly all these bodies have been removed in quarrying. The breccia and the shale-sandstone masses appear to have originated from two separate geologic processes which occurred at two different times. The origin of the breccia is in doubt because not enough critical evidence is available to prove conclusively any single origin. The authors believe, however, that the breccia probably is the product of a submarine rock slump during St. Louis time which was triggered by the tectonic activity that initiated early movements along the Mt. Carmel Fault. Other possible origins, such as solution of evaporites accompanied by collapse of overlying rock or formation of caves in a karst terrain followed by roof collapse, are not supported by the evidence observed. The shale-sandstone bodies are believed to be rocks of Pennsylvanian age which were deposited in caverns developed during the Mississippian-Pennsylvanian erosion interval. The limestone conglomerate probably is of the same age as the shale-sandstone bodies.