Rosebud Mining Company’s Toms Run Mine is a underground mine on the Upper Freeport coal seam located in Burrell Township, Indiana County Pennsylvania northeast of the town of Blairsville. The mine entrance is a drift off of the coal crop located on the northwest flank of the Chestnut Ridge anticline. The Upper Freeport coal averages approximately 50 inches in thickness over the reserve area. Most of the mining is slightly south and west of the mine entrance and extends down dip past the axis of the adjacent Latrobe Syncline, where the Upper Freeport coal acquires a cover of over 800 feet. Dips on the flank of the anticline exceed 10o but the coal is relatively flat on either side of the synclinal axis. Structural elevations within the mine range from 1160 feet to near 400 feet above mean sea level.

A portion of the reserve area is overlain by draw rock, or rock in the immediate roof that falls as the coal is mined or soon after. The draw rock varies in thickness from nothing to over ten feet and the thickness has been mapped using available drill hole data and in-mine measurements. The draw rock is a clayey siltstone that typically has a churned, non-bedded appearance with a crude, color banding upward and contains numerous vitrainized plant fossils interpreted as logs and branches. Genetically, the argument is made herein that draw rock was emplaced catastrophically as a single depositional event. Paleontological and sedimentological evidence are provided to support the single-event hypothesis. The possibility of a more regional distribution of the draw rock, and, by extension, of the catastrophic single event, is also considered.