Deposits
Sediments of the Upper Pottsville Mary Lee coal zone are Lower Pennsylvanian in age and comprised of cyclic sequences that include sandstone, siltstone, shale, and coal. Located within the middle of the Black Warrior Basin stratigraphic sequence, the Mary Lee and Blue Creek horizon is situated below drainage throughout the Property and is accessed by shafts.
The lithologic variability of the Mary Lee - Blue Creek sequence and enclosing strata is discussed below:
> The New Castle seam is present approximately 20 to 50 feet above the Mary Lee seam.
> Lithologic composition of the roof strata varies throughout the Property but consists primarily of a coarsening-upward sequence of shale or sandy shale, with occasional sandstone channels located within the immediate or main roof of the Mary Lee seam.
> In areas where sandstone occupies the immediate roof of the Mary Lee seam, seam scouring may locally occur. Where sandstone channels are present within 4 to 6 feet above the Mary Lee (roof bolt horizon), there is potential for increased drawrock conditions and roof instability beneath the sandstone/shale contact.
> Areas, where the combined thickness of the Mary Lee - Blue Creek horizon is less than a minimum continuous miner cutting height (7.0 feet), are shown, which as a result, roof (and/or floor) strata are expected to be excavated as out-of-seam dilution (050).
> Thickness and composition (shale, ca ........