Cottonwood Limestone

Cottonwood Limestone
Stratigraphic range: Asselian PreꞒ Ꞓ O S D C P T J K Pg N (Gearyan stage)[1]
Well-exposed natural outcrop of the Cottonwood Limestone alongside the Konza Prairie Nature Trail
Type	Formation Member
Unit of	Beattie Limestone
Sub-units	Top Ledge, Bottom Ledge
Underlies	Florena Shale member of the Beattie Limestone formation
Overlies	Eskridge Shale
Thickness	3–7 ft (0.91–2.13 m) often ~6 ft (1.8 m)
Lithology
Primary	Limestone
Other	Calcareous shale and siliceous to quartz[clarification needed] nodules or infills of burrows
Location
Region	Mid-continental
Country	United States
Extent	Outcrops from southeast Nebraska to northeast-central Oklahoma[2]
Type section
Named for	Cottonwood Falls, Kansas
Named by	Prosser, C. S.
Year defined	1894-5[3][4]

Cottonwood Limestone, or simply the Cottonwood,^[5] is a stratigraphic unit and a historic stone resource in east-central Kansas, northeast-central Oklahoma, and southeastern Nebraska in the Midwestern United States.^[2] It is the lowest member of the Beattie Limestone formation and commonly outcrops within the deep valleys and on top of the scenic residual ridges of the Flint Hills.

This important building stone, quarried in the Cottonwood River valley, had been used under the names "Cottonwood stone" or "Cottonwood Falls limestone" many years before the name Cottonwood Limestone appeared in scientific publications late in the 19th century. Similarly, "Manhattan stone" was the commercial name used for the same limestone when quarried in the vicinity of Manhattan, Kansas.^[4] It was also called "Alma Limestone" when first quarried at Alma, Kansas.^[6][7]

The Cottonwood Limestone is one of the most persistent and easily recognizable horizons in Kansas.^[6][8] This limestone is usually light gray or buff in color, massively bedded, and has an average thickness of about six feet. The upper part of the member in particular is recognizable for being almost entirely made up of the small wheat-grain shaped foraminifera Fusulinida, with few other animal remains. The line of outcrop of the Cottonwood is generally marked by a line of massive rectangular blocks of light gray or bleached, bone-colored limestone, often supporting a line of shrubs. Because of its resistance to weathering, it often forms a prominent escarpment. The Cottonwood Limestone is noteworthy for the persistence of this lithologic character across its range.