OBSERVATIONS THAT CONTRIBUTED TO THE RECOGNITION OF THE PERMIAN SYSTEM

In 1840 and 1841 Roderick Murchison traveled widely in Russia as far east as the Ural Mountains. During those two field seasons he recognized and mapped the Silurian, Devonian and Carboniferous Systems. In addition, upsection of the Carboniferous System, he observed extensive outcrops of, in ascending order, red sandstones, magnesian-rich limestones, red marls, and more red sandstones. During the 1840 season, Murchison assigned those rocks to the New Red Sandstone and assumed a Secondary (Triassic) age. Because those rocks contained copper, they were referred to locally as the ‘Copper Sands’. With additional work in 1841 Murchison observed that (1) the lower red sandstone contained coal plants (e.g. Calamites gigas, Pecopteris Göpperti, and Sphenopteris crosa) similar to Carboniferous plants, (2) the intermediate limestone contained fossils of the Magnesian Limestone of England and the Zechstein of Germany (e.g. Modiola Pallasi, Terebratula Schlotheimi, Productus Cancrini), and (3) the upper red sandstone contained fish and saurian fossils comparable to those of the Bunter sandstone of Germany. By the end of the 1841 season, Murchison proposed a new name, the Permian System, for the lower red sandstone and the magnesian limestone and assigned it a Paleozoic age. The overlying Bunter sandstone was assigned to the Triassic. His first public announcement of the Permian System was in a published letter to Fischer von Waldheim written in the autumn of 1841 (reprinted in The Philosophical Magazine, 1841, 19(126): 417–422). By the time The Geology of Russia was published in 1845, had further refined his classification of the Permian System. The codification of the Permian System was a good idea and has withstood the test of time.