 No igneous or metamorphic rocks exist within the county, other than possible glacial erratics.Structurally, the bedrock of Sullivan County is gently folded, with the axes of two major anticlines (including the Wilmot Anticline) and two major synclines (Bernice-Mehoopany Syncline and Noxen Syncline) each trending roughly east–west.There are three mapped faults in the Allegheny Formation between the towns of Murray and Ringdale.