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Named stone

Day Creek chert

Also called Day Creek Dolomite chert

A kind of chert (and flint)

Day Creek chertChert (and flint)Plains

Description

Day Creek chert is a Permian chert from northwestern Oklahoma and southwestern Kansas. It comes from the Day Creek Dolomite, a thin pale layer inside the Cloud Chief Formation; in Kansas that dolomite is only 2 to 3 feet thick and crops out in Clark County and parts of Comanche County. The nodules in place are often cracked by ancient tectonic stress or by fire and frost, and much of the surface chert is poor for sharp tools, so knappers peeled off the heavy cortex to find sound stone. Bailey's University of Oklahoma study found heavy Archaic use, with thermal alteration before fine tools were made, and more imported chert later. He also warns that Day Creek chert can match some Alibates and Tecovas stone, so eye identification alone is unreliable.

How to identify it

Texture
In-place surface nodules often have major fracture planes, vugs and large inclusions; much of the in-place chert is poor quality (Bailey 2000).
Inclusions
Fracture planes, vugs and large inclusions in the nodules.
Cortex
Heavy cortex; surface waste cores show that knappers peeled the nodules to expose flaws before working them (Bailey).
Heat treatment
Bailey observed that making complicated stone tools required periodic thermal alteration of the chert first.

Geology

A light gray to pink, dense, fine-grained dolomite, about 2 to 3 feet thick, with chert nodules and disseminated chert in places (Kansas Geological Survey). It lies within the Permian Cloud Chief Formation. Bailey argues that the Day Creek Dolomite has no lithostratigraphic relationship to the Alibates dolomite, although cherts from the two can share lithologies.

Where it comes from

Plains

States

Quarries and outcrops

  • Clark County and southern Comanche County, Kansas (outcrop of the Day Creek Dolomite)
  • Harper County, Oklahoma, and Clark County, Kansas (Bailey's study area, with quarries and workshops)

Used by

  • Archaic period: heavily used; most quarries and workshops are thought to date from the Archaic (Bailey 2000)
  • Late Prehistoric period: more imported chert and less Day Creek
  • Bailey ties particular grades of Day Creek chert to tool tasks such as Calf Creek points and Clear Fork gouges

Look-alikes

Stones that are easy to confuse with Day Creek chert.

  • Alibates agatized dolomite (can share lithologies; trace-element analysis is needed to separate them)
  • Tecovas jasper (can be mistaken for Alibates or Day Creek chert)
  • Baldy Hill jasper

Sources

  1. Bailey, Berkley Barnett. 2000. The geoarchaeology of Day Creek chert: Lithostratigraphy, petrology, and the indigenous landscape of northwest Oklahoma and southwest Kansas. Ph.D. dissertation, University of Oklahoma.shareok.org (opens in a new tab)
  2. Kansas Geological Survey. 1968. The Stratigraphic Succession in Kansas (Bulletin 189): Permian.kgs.ku.edu (opens in a new tab)

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