What soils cause foundation problems in north-central Oklahoma?
In short: North-central Oklahoma lies in the Central Rolling Red Prairies, a region of red soils formed over Permian shale, siltstone and old terraces 134. Its clay soils — Renfrow, Kirkland and Tabler — show cracking and slickensides that mark strong shrink-swell behavior, while loamy soils such as Pond Creek and Grant are less reactive 1235. Drought drying of these clays is the main driver of foundation settlement here.
Cities covered: Enid, Stillwater, Ponca City, Perry, Kingfisher, Guthrie, Pawnee and Cushing.
What is the climate like?
USDA soil descriptions for the region list mean annual precipitation from roughly 26 to 38 inches and mean annual temperatures of about 57 to 64 °F 2345. Oklahoma's climate shifts from humid in the east to semi-arid in the west 8, and this region sits in the subhumid middle, where long summer droughts dry clay deeply. See drought and wet cycles and moisture index by city.
What is the ground made of?
The region is mapped by USDA as Major Land Resource Area 80A, the Central Rolling Red Prairies 1. Many soils formed in material weathered from Permian-age shale and siltstone — the red beds that include the Hennessey Shale and Wellington Formation — or in old alluvium on high terraces (Quaternary alluvium and terraces).
High shrink-swell clays
- Renfrow: very deep, well drained clays from Permian clayey shale. USDA describes vertic properties: cracks at least 5 mm wide in most years and linear extensibility of 6 cm or more in the upper 100 cm. The series was established in Grant County and its type location is in Kay County 1.
- Kirkland: very deep, slowly permeable, 40 to 60 percent clay in the subsoil, with intersecting slickensides — polished surfaces formed when swelling clay shears 2.
- Tabler: very deep, moderately well drained soils with very slow permeability on nearly level old terraces, with slickensides through much of the subsoil from about 10 to 42 inches. Its type location is near Medford in Grant County 3.
An Oklahoma State University study measured cumulative linear extensibility of about 12 cm in a Kirkland-like profile and about 9 cm in a Norge-like profile, and described the Kirkland-like soil as highly expansive 7.
Loamy and shallower soils
- Pond Creek: very deep, well drained, silty soils from loess, alluvium and red-bed residuum; type location in Garfield County 5.
- Grant: well drained soils with siltstone or silty shale at 40 to 60 inches; type location in Garfield County 4.
- Kingfisher: moderately deep soils with weathered silty shale at 20 to 40 inches, mainly in north-central Oklahoma 6.
None of these three descriptions lists vertic properties 456.
What are the main soils?
| Series | Depth to rock or contact | Drainage | Shrink-swell indicators |
|---|---|---|---|
| Renfrow | > 60 in to shale | Well drained | Vertic; LE ≥ 6 cm 1 |
| Kirkland | ~82 in (typical) | Well drained, slow | Slickensides 2 |
| Tabler | Very deep | Moderately well drained, very slow | Slickensides 3 |
| Grant | 40–60 in | Well drained | Not listed 4 |
| Pond Creek | > 60 in | Well drained | Not listed 5 |
| Kingfisher | 20–40 in | Well drained | Not listed 6 |
What are the common foundation problems?
- Perimeter drying settlement on Renfrow, Kirkland and Tabler clays during drought.
- Tree-root desiccation settlement where trees grow close to homes on these clays.
- Heave when dried clays rewet after drought or tree removal.
Research using Oklahoma Mesonet data estimated statewide active zone depths — where seasonal moisture change occurs — at about 0.5 to 4 meters 8. The slow permeability of Kirkland and Tabler 23 means water enters and leaves these clays slowly.
Related
- Shrink-Swell and Active Zone
- Hennessey Shale (Group)
- Wellington Formation
- OKC Metro
- Soil Series Index
Common questions
What soils cause foundation movement around Enid and Ponca City?
Clay soils of the Central Rolling Red Prairies, such as Renfrow, Kirkland and Tabler, have vertic or vertic-like properties including cracking and slickensides, which indicate strong shrink-swell behavior.
Are all soils in north-central Oklahoma high shrink-swell?
No. Soils such as Pond Creek, Grant and Kingfisher are loamy, formed in silty material or siltstone and shale, and their USDA descriptions do not list vertic properties.
How much rain falls in north-central Oklahoma?
USDA descriptions for the region's main soils list mean annual precipitation of roughly 26 to 38 inches, with typical values in the low to mid 30s.
What is a slickenside?
A slickenside is a polished, grooved surface inside a clay soil, formed when the clay swells and blocks of soil shear past each other. It is a field sign of high shrink-swell clay.
Sources
- Official Series Description – RENFROW Series USDA Natural Resources Conservation Service
- Official Series Description – KIRKLAND Series USDA Natural Resources Conservation Service
- Official Series Description – TABLER Series USDA Natural Resources Conservation Service
- Official Series Description – GRANT Series USDA Natural Resources Conservation Service
- Official Series Description – POND CREEK Series USDA Natural Resources Conservation Service
- Official Series Description – KINGFISHER Series USDA Natural Resources Conservation Service
- Shrink-Swell and Other Characteristics of Five Benchmark Soils of Western Oklahoma (Technical Bulletin T-150) Oklahoma State University Agricultural Experiment Station
- Soil Matric Suction and Active Zone Depth in Oklahoma (PhD dissertation) Oklahoma State University
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