Paleontology and geology
Most of Alabama lay beneath the sea throughout much of the Silurian, as evidenced by fossils of brachiopods, trilobites, crinoids, and other marine creatures. Erosion of the Taconic Mountains to the east deposited sediments in these shallow seas. One particular type of sediment produced layers of hematite iron ore, which has played an important role in Alabama’s industrial history. Although not shown on this map, these hematite layers are exposed in the Valley and Ridge Province near Birmingham and Gadsden in central Alabama. Their easy accessibility led to the state’s once thriving iron and steel industries.