The highest surviving rocks on Helvellyn, found on the summit plateaux of Helvellyn itself and of Nethermost Pike, and along the crest of Striding Edge, are the volcaniclastic sandstones of the Deepdale Sandstone Formation. Again, this formation is confined to the limits of the caldera, and represents another return to erosion and sedimentary deposition within a caldera lake, though with layers of pyroclastic rock showing that the volcanism had not entirely finished.