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Named stone

Harrodsburg, Allens Creek and Holland cherts

Also called Ferdinand chert, Holland Dark Phase, Muldraugh chert (Allens Creek), Holland chert

A kind of chert (and flint)

Harrodsburg, Allens Creek and Holland chertsChert (and flint)Midwest/Ohio Valley

Description

These three Indiana and Kentucky cherts are easy to confuse. Harrodsburg chert, from the Mississippian Harrodsburg Limestone in Hardin County, Kentucky, is highly fossiliferous and oolitic, usually white to light gray with some brown or dark gray, and full of crinoid and bryozoan fragments; it can be blocky and poorly cemented. Allens Creek chert, from the Muldraugh formation of Monroe County, Indiana, is just as fossiliferous and light gray but finer and better silicified, and one specialist could not tell them apart even under a microscope. Holland chert, from the Pennsylvanian Holland Limestone of Dubois County, Indiana, is bluish gray to black, and its dark phase (Ferdinand chert) resembles Upper Mercer chert.

How to identify it

Colour
Harrodsburg: usually white to light gray, some brown and very dark gray. Allens Creek: light gray. Holland: bluish gray, varying from black to pinkish gray; the dark phase is Ferdinand chert. Muldraugh chert at the Howard site, Kentucky: light to dark gray mottled with white to light blue.
Texture
Allens Creek is fine and well silicified; Harrodsburg is somewhat blocky and poorly cemented. Muldraugh is earthy or granular.
Luster
Muldraugh turns vitreous when heated.
Inclusions
Highly fossiliferous, oolitic in Harrodsburg: crinoids and bryozoans are common.
Heat treatment
Heating Muldraugh chert makes it more vitreous and shifts the colour to red and pink (Pollack and Schlarb).

Geology

Harrodsburg chert is from the Mississippian Harrodsburg Limestone, which occurs in Kentucky north of Taylor, Casey and Lincoln counties and continues into Indiana, above the basin-filling Fort Payne Formation. Allens Creek chert is from the Mississippian Muldraugh formation of Monroe County, Indiana. Holland chert is from the Pennsylvanian Holland Limestone (Staunton Formation, Raccoon Creek Group) in Dubois County, Indiana; the Holland and Upper Mercer limestones are of about the same age and lithology.

Where it comes from

Midwest/Ohio Valley

States

Quarries and outcrops

  • Hardin County, Kentucky (Harrodsburg chert)
  • Monroe County, Indiana (Allens Creek chert)
  • Dubois County, Indiana (Holland chert)

Used by

  • Used in the Ohio Valley; the opened sources describe sources, not periods

Look-alikes

Stones that are easy to confuse with Harrodsburg, Allens Creek and Holland cherts.

  • Upper Mercer chert (the dark Holland phase is macroscopically similar)
  • Burlington chert, a white, crinoidal chert (Boulanger)
  • Other pale fossiliferous Mississippian cherts

Sources

  1. Boulanger, Matthew T. 2022. Neutron Activation Analysis and X-ray Fluorescence of Chert Artifacts from Mielke #1 (33SH26), Shelby County, Ohio. Supplementary Text S1, Midcontinental Journal of Archaeology.midwestarchaeology.org (opens in a new tab)
  2. Pollack, David, and Eric J. Schlarb. 2009. Archaeological Investigations of the Early and Late Fort Ancient Howard Site (15MA427), Madison County, Kentucky. Kentucky Archaeological Survey Report 151.kentuckyarchaeologicalsurvey.org (opens in a new tab)
  3. U.S. Geological Survey. The Geology of Kentucky: Mississippian System (Professional Paper 1151-H).pubs.usgs.gov (opens in a new tab)

All materials