# New Albany Shale

Canonical page: https://lithomap.app/resources/geologic-formations/united-states/new-albany-shale
Last reviewed: September 17, 2026
Page purpose: Comprehensive United States geologic formation reference for human readers, search systems, and language models.
Major region: Midwest / Great Lakes
Regional setting: Illinois Basin and adjacent Cincinnati Arch
Age: Late Devonian to earliest Mississippian
Age detail: Mostly Late Devonian, with locally older basal or younger upper beds
Depositional setting: Stratified marine basin with oxygen-poor deeper water
Rock types: Black shale, Gray-green shale, Siltstone, Thin carbonate beds
States in recognized usage: Illinois, Indiana, Kentucky

## Summary

The New Albany Shale is an organic-rich marine unit of the Illinois Basin whose dark beds record restricted seafloor conditions and whose lighter layers capture changes in oxygen and sediment supply.

## Distribution

The New Albany is exposed around portions of the Illinois Basin in Indiana and Kentucky and continues beneath Illinois and adjoining areas. State usage may treat it as a formation or group and may divide it into different members.

Thickness and age expand toward the basin interior. Weathered outcrops can look rusty, pale, or crumbly rather than black because pyrite and organic matter react near the surface.

## Geological history

Fine mud and organic particles settled through a layered sea in which bottom water was commonly oxygen-poor. Periodic circulation and shoreline shifts produced greenish-gray, bioturbated, silty, or carbonate-rich beds among the dark shale.

Compaction and burial converted the sediment to shale and generated hydrocarbons from organic matter. Weathering later altered feldspar, calcite, pyrite, and chlorite and formed sulfate and iron minerals near exposed surfaces.

## Fossil record

Conodonts, radiolarians, spores, Tasmanites-like organic microfossils, fish scales and teeth, wood fragments, and thin-shelled brachiopods occur. Better-oxygenated marginal facies may contain a broader shelly fauna and abundant trace fossils.

Dark shale may contain few obvious hand-specimen fossils even when microscopic and chemical evidence of life is abundant. Fossil expectations must therefore follow facies and member, not color alone.

## Minerals and geological resources

Clay minerals and quartz dominate, with feldspar, calcite, pyrite, and organic matter in varying amounts. Weathering can form gypsum, jarosite, goethite, and other iron oxides or sulfate salts.

Natural gas is an organic geological resource rather than a mineral. Fresh pyrite-bearing shale can produce acidic drainage, and roadside weathering crusts are not reliable indicators of unaltered rock composition.

## Field context

- Fresh and weathered shale can look very different; record whether a sample came from intact bedrock.
- Shale slopes fail easily, especially when wet or undercut.
- Use state-specific terminology because rank and member names change around the basin.

## Connected field guides

- Shale (rock; Named rock type and mineral context) — https://lithomap.app/resources/rock-identification/shale
- Siltstone (rock; Named rock type) — https://lithomap.app/resources/rock-identification/siltstone
- Calcite (mineral; Mineral discussed in this formation) — https://lithomap.app/resources/mineral-identification/calcite
- Feldspar (mineral; Mineral discussed in this formation) — https://lithomap.app/resources/mineral-identification/feldspar
- Goethite (mineral; Mineral discussed in this formation) — https://lithomap.app/resources/mineral-identification/goethite
- Gypsum (mineral; Mineral discussed in this formation) — https://lithomap.app/resources/mineral-identification/gypsum

Mapped location and formation context support an identification but cannot establish one. Compare several physical properties and use laboratory analysis when the material remains ambiguous.

## Connected state geology guides

- No directly overlapping state guide is currently published.

## Authoritative sources

- Kentucky Devonian stratigraphy — U.S. Geological Survey: https://pubs.usgs.gov/pp/p1151h/devonian.html
- New Albany paleoenvironment — U.S. Geological Survey: https://www.usgs.gov/publications/paleoenvironment-new-albany-shale-group-devonian-mississippian-illinois
- New Albany weathering mineralogy — U.S. Geological Survey: https://www.usgs.gov/publications/weathering-new-albany-shale-kentucky-usa-i-weathering-zones-defined-mineralogy-and

## Formation photograph

- Image: https://lithomap.app/_delivery/formations/new-albany-shale.webp
- Description: Dark, chippy-weathering New Albany Shale exposed at MacDonald Knob in Kentucky
- Creator: James St. John
- License: CC BY 2.0 — https://creativecommons.org/licenses/by/2.0/
- Source record: https://commons.wikimedia.org/wiki/File:New_Albany_Shale_(Upper_Devonian%3B_MacDonald_Knob_Outcrop%2C_Bullitt_County%2C_Kentucky%2C_USA)_11_(44085616790).jpg

Formation-level information does not prove that a fossil or mineral occurs at a specific coordinate. It also does not establish ownership, access, collecting permission, present conditions, or specimen identity.