What is Niotaze soil and how does it affect Oklahoma foundations?

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

In short: Niotaze is a soil of wooded hillsides in north-central and northeastern Oklahoma, with a stony sandy surface over a dense clay subsoil and shale 20 to 40 inches down. It is somewhat poorly drained, and its smectitic clay subsoil is the type associated with shrink-swell. Homes on Niotaze can face both clay movement and wet-soil problems, with soft rock fairly close to the surface.

What is Niotaze soil?

Niotaze is an official USDA soil series classified as "Fine, smectitic, thermic Albaquic Hapludalfs" ¹. It formed in residuum (rock weathered in place) from interbedded Pennsylvanian shale and sandstone, with a surface layer of sandstone colluvium (material that slid or washed downslope) ¹. It sits on backslopes of hills and cuestas, with slopes of 3 to 45 percent ¹.

The series covers about 350,000 acres, about 300,000 of them in Oklahoma and the rest in southeast Kansas ¹. It occurs in the Northern Cross Timbers (MLRA 84A) of north-central and northeastern Oklahoma ¹. The type location is in Chautauqua County, Kansas ¹. Mean annual precipitation is 39 to 45 inches ¹. Native vegetation is oak-hickory savannah with tall grasses ¹.

In Oklahoma, Niotaze is mapped in the Tulsa Metro and Northeast (Ozark Plateau and Grand Lake) regions, over Pennsylvanian shales.

What is the typical soil profile?

Source for the table: ¹. Other properties from the official description ¹:

• Drainage: somewhat poorly drained; permeability slow ¹.
• Depth to shale: 20 to 40 inches ¹.
• Clay jump: clay rises by more than 20 percentage points within about 3 inches going from the E layer into the Bt ¹.
• Mineralogy: smectitic, though both smectitic and mixed pedons have been sampled ¹.

What does it mean for foundations?

Shrink-swell clay

Clay soils swell as they gain water and shrink as they dry, and uneven moisture change under a shallow foundation causes uneven movement ⁵. A federal survey of expansive materials identified montmorillonite, a smectite clay, as a main contributor to expansive soils, notably in the Great Plains ⁴. Niotaze's subsoil is 35 to 55 percent clay and is classed as smectitic ¹. The USDA rates shrink-swell as linear extensibility, with 6 to 9 percent "high" and 9 percent or more "very high" ⁶; the value for a mapped unit is in Web Soil Survey ².

Patterns to read about:

• Perimeter drying settlement (edge drop)
• Perimeter wetting heave (edge lift)
• Tree-root desiccation settlement

Wet soil and slow drainage

An abrupt textural change, where clay increases sharply over a short distance, significantly restricts water movement ³. Niotaze has this abrupt change at the top of its clay subsoil and is somewhat poorly drained ¹. See groundwater and perched water, crawl space moisture and wood decay and lateral earth and hydrostatic pressure on walls.

Shale close to the surface

Shale at 20 to 40 inches ¹ is shallower than typical pier depths. Oklahoma steel push pier records show typical depths of about 8 to 16 feet, with a median near 12 feet in Tulsa ⁷. The upper shale in Niotaze is described as weakly cemented and slaking in water ¹, meaning it breaks down when soaked.

Related

• Soil series in the Tulsa metro
• Bedrock in the Tulsa metro
• Shrink-swell and the active zone
• Clay mineralogy
• Soil series index