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

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

In short: Dennis is a very deep clayey soil of northeastern Oklahoma, first described in Wagoner County and typified near Claremore. It is somewhat poorly drained, with a perched water table 12 to 30 inches down in winter and spring, and its subsoil holds 28 to 50 percent clay. Seasonal saturation followed by summer drying is the main soil condition behind foundation movement on Dennis.

Where does Dennis soil occur?

The USDA Natural Resources Conservation Service (NRCS) Official Series Description (OSD) maps Dennis in southeastern Kansas, southwestern Missouri and eastern Oklahoma, mostly in Major Land Resource Area 112 (the Cherokee Prairies), with smaller areas in MLRA 76 and LRUs 84A, 116A and 118B ¹. It is an extensive series ¹. The type location is about half a mile north of Claremore in Rogers County, and the series was established in Wagoner County in 1941 ¹.

Dennis forms on interfluves and hillslopes on plains, on slopes of 0 to 8 percent, commonly 1 to 5 percent ¹. It weathered from Pennsylvanian shale ¹. Its type location near Claremore and its founding in Wagoner County place it in the Tulsa metro area; see also the neighboring East-Central (Arkoma) region. See soil series of the Tulsa metro for neighboring soils.

What are the key properties of Dennis soil?

"Argiudolls" are prairie soils with a dark topsoil and a clay-enriched subsoil in a humid climate; "Aquic" marks periodic wetness. Dennis is mainly cropland for small grains, sorghum, soybeans and some cotton, with tame pasture and native tallgrass range ¹.

What do these properties mean for foundations?

Perched water

A perched water table is a local saturated zone held above the main groundwater by a slowly permeable layer, usually clay ⁵. In Dennis it ranges from 12 to 30 inches below the surface from December through April in normal years ¹. Wet conditions at that depth relate to crawl space moisture and wood decay and groundwater and perched water.

Clay that swells and shrinks

Clay soils swell (heave) when they gain moisture and shrink when they dry, and uneven changes do more damage than uniform ones ⁴. Dennis's subsoil holds 28 to 50 percent clay ¹. NRCS rates shrink-swell by linear extensibility percent (LEP): under 3 percent low, 3 to 6 percent moderate, 6 to 9 percent high and 9 percent or more very high ³. Web Soil Survey lists the LEP for each Dennis map unit ². A wet winter edge and a dry summer edge are the patterns described in perimeter wetting heave and perimeter drying settlement.

Repair depth context

In Oklahoma steel push pier records, piers (steel pipes driven to firm bearing below the moving clay) typically reached 8 to 16 feet, with a median near 12 feet in Tulsa ⁶. Dennis itself is very deep, with a solum thicker than 60 inches ¹.

What should you know about a Dennis lot?

• Look up the map unit, water table and LEP in Web Soil Survey ².
• Grade soil away from the house and send downspout water well away from the foundation ⁴.
• Water evenly on all sides during dry spells, with extra attention to the sunnier south and west sides ⁴.
• Track cracks and check drainage each year ⁴.

Related

• Choteau soil
• Eram soil
• Shrink-Swell and Active Zone
• Steel Push Piers
• Soil Series Index