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.