What is Bates soil and how does it affect Oklahoma foundations?
In short: Bates is a well-drained, loamy prairie soil formed from Pennsylvanian sandstone in eastern Oklahoma, southeastern Kansas and southwestern Missouri. It reaches soft sandstone or shale at 20 to 40 inches. Its swell potential is lower than the clay soils around it, so drainage, erosion, fill and shallow rock are the main foundation questions.
What does the official description say?
| Property | Value |
|---|---|
| Taxonomic class | Fine-loamy, siliceous, active, thermic Typic Argiudolls 1 |
| Parent material | Residuum from Pennsylvanian sandstone, often with thin silty or sandy shale beds 1 |
| Landform | Interfluves and hillslopes on plains 1 |
| Slopes | 1–8% 1 |
| Drainage | Well drained; moderate permeability 1 |
| Saturated hydraulic conductivity | Moderately high to high 1 |
| Runoff | Low or medium 1 |
| Depth to soft rock (paralithic contact) | 20–40 in; about 33 in typical 1 |
| Mean annual precipitation | 35–45 in 1 |
| Extent | Extensive; MLRAs 76, 84A, 85, 87B, 112 and 118B 1 |
The type location is in Crawford County, Kansas, and the series is mapped across eastern Oklahoma 1. About half of Bates land is grassland and half is cropland 1.
Reading the class name
- Fine-loamy means the subsoil is loam to clay loam, with less clay than a "fine" (clayey) soil.
- Siliceous means the soil is dominated by quartz-type minerals rather than swelling clay.
- Argiudoll means a dark prairie topsoil over a subsoil enriched in clay, in a humid climate.
What soils are nearby?
Bates is associated with several Tulsa-area soils that behave differently 1:
| Series | How it differs from Bates |
|---|---|
| Dennis | Similar position but a fine-textured (clayey) subsoil 1; somewhat poorly drained with perched water 12–30 in, Dec–Apr 2 |
| Eram | Similar position but a fine-textured subsoil 1 |
| Collinsville | Steeper, with hard rock within 20 in 1; typical depth 9 in 3 |
| Coweta | Steeper, with bedrock within 20 in 1 |
Because these soils are mapped next to each other 1, the ground within one subdivision can change from shallow Collinsville to Bates to clayey Dennis.
How much might it swell?
Shrink-swell is rated by linear extensibility, the percent change in a soil's length from moist to dry, with under 3 percent rated low and 3 to 6 percent moderate 4. The Bates description gives no number 1. A fine-loamy, siliceous subsoil points toward the low to moderate range, and the map-unit value in the USDA Web Soil Survey is the way to confirm it.
What does it mean for foundations?
- Water and erosion. Moderately high to high hydraulic conductivity 1 lets water move readily through the loamy soil, so a plumbing leak or concentrated roof water can carry soil from beside a footing. See erosion, undermining and washout voids and plumbing leaks under slab.
- Fill on sloping lots. Bates occurs on slopes up to 8 percent next to steeper Collinsville and Coweta ground 1, so many lots are leveled with fill. See fill consolidation settlement.
- Shallow soft rock. Soft sandstone or shale at 20 to 40 inches 1 means footings may rest partly on rock. In 2025 Tulsa installation records, steel push piers reached refusal at a median depth of about 12 feet, well below the rock depths shown in soil surveys 6. See Tulsa bedrock.
- Drainage basics. The ASCE guide recommends grading at least 3 inches of fall in the first 5 feet and downspouts discharging at least 3 feet from the foundation 5.
Related
- Tulsa metro
- East-Central (Arkoma)
- Pennsylvanian sandstones
- Dennis soil
- Collinsville soil
- Soil series in the Tulsa metro
Common questions
Where is Bates soil found?
Bates is an extensive soil of southeastern Kansas, eastern Oklahoma and southwestern Missouri. It occurs on interfluves and hillslopes on plains, including the Cherokee Prairies around Tulsa.
Is Bates soil expansive?
Bates has a fine-loamy, siliceous subsoil rather than a clayey, smectitic one, so it is not in the high shrink-swell group. Neighboring Dennis and Eram soils, which have clayey subsoils, are more likely to swell.
How deep is the rock under Bates soil?
Soft (paralithic) sandstone or shale lies 20 to 40 inches below the surface; about 33 inches in the typical profile.
What problems are common on Bates soil?
With low swell potential, the usual concerns are water: runoff, leaks washing out loamy soil beside footings, fill on sloping lots, and uneven bearing where soft rock is shallow.
Sources
- Official Soil Series Description: BATES Series USDA Natural Resources Conservation Service
- Official Soil Series Description: DENNIS Series USDA Natural Resources Conservation Service
- Official Soil Series Description: COLLINSVILLE Series USDA Natural Resources Conservation Service
- Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook) UC Davis California Soil Resource Lab
- Living With Shrink/Swell Soils: A Homeowners' Guide to Maintenance of Shallow Foundations American Society of Civil Engineers, Geo-Institute
- Oklahoma steel push pier installation records, 2025 (unpublished field data) TerraBrain field data
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