Pennsylvanian Deposition and Erosion
325 to 286 million years ago
Uplift and erosion occurred during the end of the Mississippian and the beginning of the Pennsylvanian times. In later Pennsylvanian time, sandstone deposits were formed over much of the Ozarks. In northern Missouri conditions were different and coal swamps developed. These beds of coal are today found between layers of sandstone and limestone. In late Pennsylvanian time, the area was again uplifted and another period of erosion began.
The Appalachian Mountains continued to grow as the collision in the east continued. Another collision began to the south between the South American and North American plates. This collision produced the Marathon Mountains of Texas and the Ouachita Mountains of Arkansas and Oklahoma. This collision and mountain building so close to the south of the Ozarks was most likely responsible for the uplift and change in conditions of the Pennsylvanian time.
Faulting along the Bolivar-Mansfield Fault Zone involves Pennsylvanian age rocks and may have been activated during this time by the Ouachita collision to the south.
The Ozark area was still in the tropics south of the