Silurian Period   Origin of the Term Silurian System. [1835] Established by Roderick Murchison for rocks with distinctive fossils that was originally classified as Transitional (a Wernerian term) in Wales. Silurian was the generally accepted pre-Devonian (Old Red Sandstone) system for all the Lower Paleozoic. Murchison was director of the Geological Survey of Great Britain from 1855 to 1871, so it isn't surprising that Cambrian wasn't accepted. Stanley M. Awramik