Tarkio Limestone

The Tarkio Limestone, is a Late-Carboniferous member of the Zeandale Formation in Kansas, extending into Nebraska, Iowa, and Missouri.^[2][1] The unit was named for outcrops in the Tarkio Valley in northwestern Missouri, however, R.C. Moore designated a typical exposure of this unit on Mill Creek, southwest of Maple Hill, Kansas.^[3] Owing to its unusual coloration, an early name for this rock was chocolate limestone.^[2] This rock can be recognized by its coloration and abundant fusulinids, Triticites ventricosus, protruding from the surfaces, giving a "raspy" texture.^[4]

Tarkio Limestone
Stratigraphic range: [1]Gzhelian PreꞒ Ꞓ O S D C P T J K Pg N ↓ (Virgilian stage)[2]
Slumped blocks of Tarkio Limestone tumbling into Deep Creek below Pillsbury Crossing in Riley County, Kansas
Type	Member
Unit of	Zeandale Limestone of Wabaunsee Group
Underlies	Wamego Shale member of Zeandale Limestone
Overlies	Willard Shale
Lithology
Primary	Limestone
Location
Region	Kansas
Country	United States
Type section
Named for	Outcrops in the Tarkio Valley in northwestern Missouri
Named by	G.E. Condra[2]
Year defined	1935

The Tarkio Limestone forms bold bluffs along Deep Creek in southeastern Riley County, Kansas and can be easily accessed there at Pillsbury Crossing,^[3] about 30 miles (48 km) west of Maple Hill.

See also

• Earth sciences portal
• Kansas portal
• Paleontology portal

• List of fossiliferous stratigraphic units in Kansas
• Paleontology in Kansas