| Tarkio Limestone | |
|---|---|
| Stratigraphic range: [1] (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, 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]
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.
