Nevadan orogeny related to the accretion of these volcanic arc terranes is mostly limited to the western regions of the resulting mountain ranges (Klamath Mountain range and Sierra Nevada Mountains) and is absent from the eastern regions. In addition, the deformation experienced in these mountain ranges is mostly due to the Nevadan orogeny and not other external events such as the more recent Sevier and Laramide Orogenies. It is noted that the Klamath Mountains and the Sierra Nevada mountains share similar stratigraphy indicating that they were both formed by the Nevadan orogeny. In comparison with other orogenic events, it appears that the
Antler orogeny due to sea-level rise in the Cambrian rather than displacement from an ocean basin. The sedimentary effects of the Antler orogeny are well known and well described in many published reports, but the exact nature of that event and the driving force remain unsettled. Among the unanswered questions are these: what aspect of plate tectonics was involved; what effect did the Alamo impact event have; why did marine basins appear in the area of general uplift; why did the western facies assemblage, and not the eastern assemblage, include bedded chert, basaltic bodies, barite deposits, and sulfide deposits. Antler orogeny The