It juxtaposes two successions dominated by mudrocks that are of similar age. To the north of the fault, the Ordovician Skiddaw Group is represented by the Kirk Stile Formation, to the south by the Buttermere Formation, both of Arenig age. The younger sequence of volcanic rocks overlying the Skiddaw Group also differs, with the Eycott Volcanic Group to the north and the Borrowdale Volcanic Group to the south. The fault is described as a thrust near Causey Pike, where rocks of the Crummock Water Aureole are emplaced over sandstone olistoliths of the Buttermere Formation, but the overall displacement on this structure is oblique, with a significant component of sinistral (left lateral) strike-slip motion.