Taconic orogeny Taconic orogeny The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the United States. As the mountain chain eroded in the Silurian and Devonian periods, sediments from the mountain chain spread throughout the present-day Appalachians and midcontinental North America. Beginning in Cambrian time, about 550 million years ago, the Iapetus Ocean began to close. The weight of accumulating sediments, in addition to compressional forces in the crust, forced
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