Warrior coal field
The Warrior coal field or Warrior coal basin is a 7,810 square mile expanse of land in Jefferson, Blount, Cullman, Fayette, Tuscaloosa, Walker, and Winston counties which is underlain with bituminous coal seams and drained primarily by the Black Warrior River, with the exceptions of its northernmost areas, which are drained by the Tennessee. Many of the coal fields seams are at their thickest in the east central section, centered in eastern Walker County, and it is there and in adjoining northwest Jefferson County that the most productive mining operations were established.
Alabama's coal fields, part of the Ohio coal basin, were once continuous, but were interrupted by the uplift of the Appalachian mountain chain. The Warrior field is by far the largest and most productive of the state's three major coal fields, and produces the highest quality coal. On the whole, the coal field has a saucer or basin shape, rising at the edges and sloping generally down to the southwest, where it is overlain by newer sedimentary layers. Where it abuts the foothills of the Appalachians in southeastern Jefferson County its coal strata are folded and fractured by the process of upheaval.
The Warrior coal field was described and named in 1848 by state geologist Michael Tuomey, but first commercially exploited in the 1870s. Major seams in the Warrior coal field, which range from 3 to 5 feet thick, include the Pratt group near the surface, the Mary Lee group lying 500 feet lower, and the Black Creek group another 500 feet below that. The seams are separated by various series of sandstone, conglomerate rock, shales, slate, an thin beds of limestone.
Groups, seams and beds
- Pratt group
- Mary Lee group, laid down in the Pennsylvanian subperiod of the Carboniferous period of the Paleozoic era (between 300 and 320 million years ago)
- Black Creek group
- McCalley, Henry (1886) On the Warrior Coal Field". Montgomery: Geological Survey of Alabama
- White, Marjorie Longenecker (1981) The Birmingham District: An Industrial History and Guide. Birmingham: Birmingham Historical Society ISBN 9990230099