Coral-stromatoporoid bioherms are present in the lower part of the Lockport Dolomite (Niagaran Series) of the western West Virginia subsurface. Between these organic buildups is a bedded, argillaceous dolomite with very sparse fauna, and underlying the Lockport is the Keefer Sandstone which served as the firm substrate on which Lockport benthic communites were established. During a transgression of the Middle Silurian sea, areas of thicker Keefer sand stood as submerged topographic highs. The local relief provided optimum sites for the bioherms to develop and protected the fauna from being overwhelmed by incoming terrestrial clays. Conversely, the shaly interbioherm deposits are in areas of thinner Keefer Sandstone. A minor regression followed and is represented by intert dal sediments. Growth of bioherms ceased when the area emerged above the level of low tide.

Two southwest-northeast tracts of thicker Lockport Dolomite and Keefer Sandstone mark the trends of Keefer topographic highs and associated Niagaran bioherms. These trends now offer the best potential for gas in the Middle Silurian of western West Virginia.