The highland area along the southern margin of the Meyaneh basin is underlain by late Devonian? metasediments, Carboniferous dolomitic limestone, and Jurassic sandstones and limestone. The Tertiary section in the basin includes Eocene tuffs and intercalated marine limestone, and the late Oligocene-early Miocene Qum formation, consisting of a marine member, predominantly limestone and calcareous shale, in the southern part of the region and a volcanic member, predominantly tuffaceous, in the north and northwest. The formation is under-and overlain by red beds. The upper red beds (and evaporites), regarded as equivalents of the Fars formation in southwest Iran, are intensely deformed along northwest-trending lines. Pliocene and Pleistocene conglomerates overlie the older rocks in places.