The Mescal Limestone is precambrian in age, and has been dated to be 1.2 Billion years old. Occurring mainly in Southeastern Arizona, the Mescal contains limestone, dolomitic limestones, and large amounts of cherts. The Mescal can be divided into three readily recognized members: A bedded lower member, a stromatolite bearing algal member, and a upper argillite member. Many areas of the Mescal have been metamorphosed by adjacent diabase sills over time, and few areas have not been affected by either silicification, or contact metamorphism. In the upper algal member of the Mescal a massive bed of crossbedded sandy conglomerate exsists. The crossbedded facies rests on a laminar bedded facies. The laminar bed represents more of a tidal flat deposit, with a low energy deposition. The crossbedded and more conglomeratic facies represents a very near shore subaerial dune deposit where the energy was much higher.