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How do western Oklahoma red beds affect foundation soils?

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

In short: Much of western Oklahoma is built on Permian red beds, reddish sandstone, siltstone, shale and claystone laid down about 265 million years ago along with salt and gypsum. Soft sandstone and siltstone weather into shallow, silty soils, while claystone and the old river clays washed from it produce expansive clay soils. Which one a house sits on largely decides how it moves.

What are red beds?

Red beds are sedimentary rocks colored red by iron oxide. Oklahoma's Permian red beds, about 265 million years old, include red shale and sandstone along with salt and gypsum 1. The state rock, the rose rock, comes from these Permian red beds 1.

A USGS study at a site near Union City in Canadian County described the Dog Creek Shale as mainly reddish-brown shale with thin siltstone beds, and the underlying Chickasha Formation as shale with siltstone, mudstone conglomerate and sandstone 2. Gypsum occurred as nodules and veins, and hairline fractures filled with satin spar (a fibrous gypsum) were common in the upper 18 meters 2. About 1.5 to 2 meters of soil covered the red beds there 2.

What soils form from the red beds?

Shallow loamy and silty soils on soft rock

Series Parent material Depth to soft rock Slopes
Woodward Soft, calcareous sandstone or siltstone 6 20–40 in 6 1–40% 6
Quinlan Soft, calcareous Permian sandstone or siltstone 7 10–20 in 7 1–50% 7

Both are well drained and of large extent in western Oklahoma, a few southern Kansas counties and northwestern Texas 67.

Clay soils on claystone and old terraces

Series Parent material Shrink-swell clues
Vernon Clayey residuum from Permian red-bed claystone 3 Very slow permeability; 0–2% gypsum 3
Tillman Alluvium from Permian red-bed clays and claystone 4 Cracks deeper than 48 in; COLE above 0.06 in the upper 100 cm 4
Hollister Pleistocene calcareous clays over Permian sediments 5 Smectitic Vertisol; cracks over 30 in deep 5

Hollister's cracks remain open for 150 or more cumulative days in most years, and slickensides (polished shear faces) begin 8 to 20 inches down 5. Hollister and Tillman are both extensive in the Central Rolling Red Plains of Texas and Oklahoma 45.

The coefficient of linear extensibility (COLE) measures how much a soil shrinks as it dries. Values of 0.06 to 0.09 are rated high and 0.09 or more very high 8. Tillman's reported COLE above 0.06 4 places it at least in the high class.

What does this mean for foundations?

Expansive clay sites

On Hollister, Tillman and Vernon soils, the clay can shrink deeply in dry weather and swell when rain returns 345. Cracks reaching 30 to 48 inches or more 45 show how deep seasonal drying can go. See perimeter drying settlement, center heave and the active zone.

Shallow soft rock and runoff

Woodward and Quinlan have soft rock within 10 to 40 inches and occur on slopes up to 40 to 50 percent 67. Footings may bear partly on soft rock, and runoff on slopes can erode soil at slab edges. See erosion, creeks and slopes.

Gypsum and salt

Gypsum within red-bed shale 2 and in some soils 3 links these areas to the dissolving-rock problems described on the Blaine gypsum page.

Free, plain-English answers. It asks a few questions and walks you to the repair that fits.

Common questions

What are red beds?

Red beds are sedimentary rocks such as sandstone, siltstone, shale and claystone colored red by iron oxide. In western Oklahoma they date to the Permian Period, about 265 million years ago, and are interlayered with salt and gypsum.

Why are some western Oklahoma soils so expansive?

Clays weathered from red-bed claystone, or washed off it into old terraces, can be highly expansive. Hollister, a smectitic clay, for example, has cracks more than 30 inches deep that stay open 150 or more days in most years.

Are all red-bed soils clayey?

No. Woodward and Quinlan formed from soft red sandstone or siltstone and are loamy or silty, with soft rock at 10 to 40 inches. They are less clayey and occur on slopes of up to 40 to 50 percent.

Does gypsum show up in red-bed soils?

It can. The Vernon soil may contain up to 2 percent gypsum, and shale in the red beds near Union City contains gypsum nodules and veins.

Sources

  1. The Oklahoma Geological Survey and the geology of Oklahoma USGS National Geologic Map Database (DMT '25)
  2. Geologic and Hydraulic Characteristics of Selected Shaly Geologic Units in Oklahoma (WRI 96-4303) U.S. Geological Survey
  3. Official Soil Series Description: VERNON Series USDA Natural Resources Conservation Service
  4. Official Soil Series Description: TILLMAN Series USDA Natural Resources Conservation Service
  5. Official Soil Series Description: HOLLISTER Series USDA Natural Resources Conservation Service
  6. Official Soil Series Description: WOODWARD Series USDA Natural Resources Conservation Service
  7. Official Soil Series Description: QUINLAN Series USDA Natural Resources Conservation Service
  8. Linear Extensibility (definition and shrink-swell classes, after NRCS National Soil Survey Handbook) UC Davis California Soil Resource Lab

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