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

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

In short: Parsons is a claypan soil of the prairies in northeast Oklahoma, with about a foot of silt loam sitting abruptly on dense clay. Water perches on that clay 6 to 18 inches below the surface from December through April. Homes on Parsons deal with seasonal wetness near the surface and a clay subsoil that can change volume with moisture.

What is Parsons soil?

Parsons is an official USDA soil series classified as "Fine, mixed, active, thermic Mollic Albaqualfs" ¹. The "aqu" in its name points to aquic conditions, which in soil science means periodic saturation and reduction ³. The soil formed in clayey old alluvium or in residuum from fissile (thin-splitting) Pennsylvanian shales, possibly with a thin loess cap ¹.

It occurs on interfluves, divides and paleoterraces on plains, with slopes of 0 to 3 percent ¹. The series is mapped in northwestern Arkansas, southeastern Kansas, southwestern Missouri and eastern Oklahoma and is rated as extensive ¹. Its type location is about 1.75 miles north of Wagoner, Oklahoma; the series was established in Labette County, Kansas, in 1926 ¹. Mean annual precipitation is about 41 inches (range 38-45) ¹. Native vegetation is tall grass prairie ¹.

In Oklahoma, Parsons falls in the Tulsa Metro and Northeast (Ozark Plateau and Grand Lake) regions, on Pennsylvanian shales.

What is the typical soil profile?

Depth	Layer	Texture
0-9 in	A	Silt loam
9-12 in	E	Silt loam
12-22 in	Btg1	Clay
22-36 in	Btg2	Clay
36-45 in	Btg3	Clay
45-58 in	BC	Clay, with siltstone fragments
58-79 in	C	Clay

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

Clay: 10 to 27 percent in the E layer; 35 to 60 percent in the Btg, BC and C layers ¹.
Abrupt textural change: at about 12 inches, from the E layer into the clay subsoil ¹.
Water table: perched, top at 6 to 18 inches, December through April in normal years ¹.
Drainage: somewhat poorly drained; saturated hydraulic conductivity low; runoff high to very high ¹.
Solum thickness: 40 to more than 60 inches. Depth to bedrock is not stated ¹.

What does it mean for foundations?

A claypan that holds water near the surface

An abrupt textural change is a sharp increase in clay over a very short distance, and it significantly restricts water movement ³. Parsons has this change at the top of its clay subsoil ¹. A perched water table is a saturated layer resting on drier layers below, which soil scientists call episaturation ³. On Parsons, it sits 6 to 18 inches down for much of the winter and spring ¹.

Clay movement

Clayey soils swell as they gain water and shrink as they dry, and uneven moisture change around a shallow foundation causes uneven movement ⁴. Parsons' subsoil is 35 to 60 percent clay ¹. The USDA rates shrink-swell as linear extensibility, from low (under 3 percent) to very high (9 percent or more) ⁵; the value for a mapped unit is in Web Soil Survey ². See perimeter drying settlement and perimeter wetting heave.

Moisture control

The ASCE Geo-Institute guide lists roof runoff, grading, irrigation, plumbing leaks and shallow seepage as moisture sources to manage ⁴. It suggests sloping soil away from the house at least 3 inches in 5 feet, discharging downspouts at least 3 feet out, and, for shallow seepage, an upslope trench drain with a water barrier ⁴.

Common questions

What is a claypan in Parsons soil?

It is the dense clay subsoil that starts abruptly, at about 12 inches in the typical profile, directly beneath the silty surface. Clay content in that layer is 35 to 60 percent.

Does Parsons soil stay wet?

Yes. The official description lists a perched seasonal water table 6 to 18 inches below the surface, typically from December through April.

Where is Parsons soil found?

On plains, divides and old terraces in eastern Oklahoma, southeastern Kansas, southwestern Missouri and northwestern Arkansas. The type location is near Wagoner, Oklahoma.

Is Parsons soil expansive?

Its subsoil is clay with 35 to 60 percent clay. The official description gives no shrink-swell value, so the rated linear extensibility for a mapped area should be checked in Web Soil Survey.

Sources

Official Series Description - PARSONS Series USDA Natural Resources Conservation Service
Web Soil Survey - Home USDA Natural Resources Conservation Service
A Glossary of Terms Used in Soil Survey and Soil Classification USDA Natural Resources Conservation Service
Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations Geo-Institute of the American Society of Civil Engineers
Linear Extensibility Percent UC Davis California Soil Resource Lab (SoilWeb), citing the USDA-NRCS National Soil Survey Handbook

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