Lead Creek Limestone Member,
Type locality and use of name: The name Ferdinand Limestone was applied to a so-called marine zone, including carbonate rocks (Franklin and Wanless, 1944, p. 88-89), some 15 feet (4.6 m) above the Fulda Limestone (as then called), which was said to be best developed northeast of Ferdinand, Dubois County, Ind., in T. 3 S., R. 4 W. No exposure is known at a location specifically cited by Franklin for that township, but there is a characteristic exposure 1 mile (0.6 km) northwest of Ferdinand in the NW¼NW¼ sec. 29, T. 3 S., R. 4 W. In 1964 the Ferdinand was assigned member rank in the upper part of the Mansfield Formation (Thompson and Shaver, p. 15-16), and still later Shaver and Smith, 1974, p. 6) this unit was designated as the Ferdinand Bed of the Lead Creek Limestone Member (Mansfield Formation).
Description: The Ferdinand, generally lying about 40 feet (12 m) below the top of the Mansfield, ranges from 2 to more than 3 feet (0.6 to > 0.9 m) in thickness and is dark-blue to gray argillaceous fossiliferous limestone that in some places is nearly all chert. In some places it consists of two limestones separated by 1 foot (0.3 m) of chert. Large crinoid columnals are present in a part of the southern Ferdinand distribution. Northward the bed becomes rather impure and includes calcareous siltstone and shale (Hutchison, 1976, p. 28).
The Ferdinand is underlain by blue-gray shale and a bright blocky l-foot (0.3-m) coalbed (Franklin and Wanless, 1944) it is overlain by black soft shale and massive sandstone that is fine grained, carbonaceous, and micaceous. Both contacts are apparently conformable.
The Ferdinand is well represented along the outcrop belt in Spencer County and southern Dubois County, where it is generally found associated with the Fulda Bed 10 feet or more (3.0 m) below. Northward it becomes thinner and is found sporadically as far north as Warren County within tentatively to positively identified upper Mansfield rocks. (See Kottlowski, 1959 and 1960; Shaver and Smith, 1974, p. 7-9; and Hutchison, 1976, p. 28; Hutchison's use of the name should have been "Ferdinand Bed," not "Ferdinand Limestone Bed.")
Correlation: The Ferdinand Bed includes the Grandview Limestone of Franklin and Wanless (1944) in southern Spencer County and coextends to the upper ledge of the Lead Creek Limestone Member (Tradewater Formation) in Hancock County, Ky., and probably also to the upper limestone of two exposed at Morgantown, Butler County, Ky. (Thompson, Shaver, and Riggs, 1959).
Together with the Fulda Bed, the Ferdinand contains key micro faunas, including representatives of the ostracod Zone of Amphissites rothi and the fusulinid Zone of ProfusuIinella. On this basis the Ferdinand has been assigned a late Bashkirian age (global standard late Morrowan, American standard) by Shaver and Smith (1974), Shaver (1984), and Shaver and others (1985), but such correlation has long been debated. (See details in the discussion on correlation in the article on the Lead Creek Limestone Member.)