Cambrian Period   Origin of the Term Cambrian System. [1835] Named by Adam Sedgwick for Transitional rocks in Wales that are found below Murchison's Silu-rian System. Sedgwick did not recognize any fossils. Sedgwick and Murchison were friends at this time. Sedgwick based his system on lithology, not fossils (it wasn't until the 1850's that fossils were discovered in his type Cambrian section). Since, in the mid-1800's, fossils were viewed as essential for the naming and recognition of systems, the Cambrian wasn't accepted by many people. It wasn't until 1879 with Lapworth's establishment of the Ordovician, that the Cambrian was reinstated (and was based on fossils). Stanley M. Awramik