How does limestone north of Tulsa affect Oklahoma foundations?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

In short: Northeastern Oklahoma's prairie country includes Pennsylvanian limestone units that alternate with shale formations. Where limestone is the parent rock, it can weather into Apperson soil, a very expansive smectite clay sitting over hard limestone about 3.5 to 5 feet down. Those lots combine strong seasonal shrink-swell with shallow rock.

What are the rock layers?

In northeastern Oklahoma, Pennsylvanian limestone and shale units alternate: the Oologah limestone is 80 to 145 feet thick, while the Nowata shale above it ranges from 50 to 600 feet ²⁴. Geologists once grouped four formations here as the "Tulsa Group," named from Tulsa County, listed upward as the Claremore, Labette, Oologah and Nowata ³. That group name is now abandoned ³.

Oologah limestone

The Oologah was described as blue cherty limestone separated by bands of black shale, 80 to 145 feet thick, in a belt about 10 miles wide running south from the Kansas line toward the Verdigris River ². Cherty means it contains chert, a hard silica rock.

Shale above and below

The Nowata, directly above the Oologah, is a series of bluish or greenish shales with a few sandstones, reported as 50 to 600 feet thick ⁴. It crops out in a narrow band between limestone escarpments near the Kansas line and in a belt about 8 miles wide east of Tulsa ⁴. Where shale such as the Nowata crops out ⁴, lots sit on shale-derived soil instead. See Pennsylvanian shales.

What is Apperson clay on limestone?

The Apperson series is the main soil formed from this limestone ¹:

Property	Apperson value
Parent material	Calcareous residuum from Pennsylvanian limestone ¹
Taxonomic class	Fine, smectitic, thermic Aquic Hapluderts (a Vertisol) ¹
Subsoil	Silty clay with slickensides ¹
Depth to hard limestone	40–60 in; about 44 in typical ¹
Drainage	Somewhat poorly drained, slow permeability ¹
Perched saturation	December through April ¹
Typical location	Osage County, north of Foraker ¹
Mean annual precipitation	About 40 in (36–44) ¹

A Vertisol is a soil defined by clay that shrinks and swells enough to crack open in dry seasons and churn itself over time. The Apperson description notes cracks that open and close periodically and slickensides, polished shear faces in the clay left by repeated swelling ¹. Smectitic means the clay is dominated by smectite, the most swelling clay mineral family.

What does this mean for foundations?

Seasonal shrink-swell. Smectite clay above the rock has cracks that open and close periodically ¹, and clayey soils swell as they take on water ⁶. Soil under a slab edge can drop in drought and rise when rain returns. See cracks that open and close seasonally and perimeter drying settlement.
Perched water in winter and spring. Saturation from December through April ¹ can wet crawl spaces and push on below-grade walls. See crawl space moisture and lateral earth and hydrostatic pressure.
Shallow hard rock. Hard limestone at about 3.5 to 5 feet ¹ limits how deep the clay goes but can make excavation harder.
Moisture control. The ASCE homeowner guide recommends even watering around the house, sloping soil at least 3 inches in the first 5 feet, and keeping trees farther away than their mature height ⁶.

Is karst a concern?

Limestone can dissolve and form karst features. The Oklahoma Geological Survey identifies the Ozark area in the northeast and the Arbuckle Mountains in the south as the state's main limestone and dolomite karst areas ⁵. See karst subsidence and sinkholes.

Common questions

Where are Pennsylvanian limestones near Tulsa?

Limestone units such as the Oologah occur in the prairie country of northeastern Oklahoma, in a belt running south from the Kansas line. They alternate with shale formations such as the Nowata, reported at 50 to 600 feet thick.

Can limestone produce expansive clay?

Yes. The Apperson soil formed in calcareous residuum from Pennsylvanian limestone, and its subsoil is smectitic silty clay with cracks that open and close and slickensides. It is classed as a Vertisol, the soil order defined by shrink-swell.

How deep is the rock under Apperson soils?

Hard limestone is 40 to 60 inches below the surface, about 44 inches in the typical profile. That is shallow enough to matter for footings but still leaves several feet of very expansive clay above it.

Do these limestones form sinkholes?

The Oklahoma Geological Survey names the Ozark area in the northeast and the Arbuckle Mountains in the south as the state's main limestone and dolomite karst areas. Any sudden local depression should still be checked on its own merits.

Sources

Official Soil Series Description: APPERSON Series USDA Natural Resources Conservation Service
Geolex unit references: Oologah USGS National Geologic Map Database (Geolex)
Geologic Unit: Tulsa (Group, abandoned) USGS National Geologic Map Database (Geolex)
Geologic Unit: Nowata USGS National Geologic Map Database (Geolex)
Mapping of Karst Terranes in Oklahoma to Identify Potential Environmental and Hydrologic Problems AAPG Search and Discovery / Oklahoma Geological Survey
Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations American Society of Civil Engineers, Geo-Institute

Was this page helpful?