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

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

In short: Abilene is a deep, well-drained soil with a clay to clay loam subsoil, formed in calcareous old river deposits on terraces in the Red Plains of Texas and southwestern Oklahoma. Its subsoil holds 35 to 50 percent clay, enough to shrink and swell with the seasons. It is less extreme than the cracking clays nearby, but moisture swings at the foundation edge still matter.

What does the official description say?

Property	Value
Taxonomic class	Fine, mixed, superactive, thermic Pachic Argiustolls ¹
Parent material	Calcareous alluvium or outwash, presumably Quaternary ¹
Landform	Treads of terraces on dissected plains ¹
Slopes	0–3%, mainly under 1% ¹
Drainage	Well drained ¹
Permeability	Moderately slow ¹
Runoff	Negligible to very low ¹
Subsoil clay	35–50% in the Bt and Btk horizons ¹
Carbonates	Secondary carbonates from about 10–28 in; calcic horizon from about 28–60 in ¹
Mean annual precipitation	About 26 in (21–30 in) ¹
Mean annual temperature	About 63°F ¹
Setting	MLRA 78, Central Rolling Red Plains and Rolling Limestone Prairies of Texas and Oklahoma ¹

The type location is in Haskell County, Texas, and the series was established in Taylor County, Texas, in 1915 ¹. It is described as extensive ¹.

Reading the class name

Fine means the subsoil is clayey.
Mixed mineralogy means no single clay mineral, such as smectite, dominates the clay.
Argiustoll means a dark, fertile prairie topsoil over a subsoil where clay has built up, in a climate that is dry for part of the year.
Pachic means the dark topsoil is unusually thick.

How much might it swell?

Soil scientists rate shrink-swell by linear extensibility, the percent a soil's length changes from moist to oven-dry. Under 3 percent is low, 3 to 6 moderate, 6 to 9 high and 9 or more very high ³. The Abilene description gives no linear extensibility value and does not describe cracks or slickensides ¹. With 35 to 50 percent clay in the subsoil ¹, a moderate to high rating is plausible, but the map-unit value in the USDA Web Soil Survey, or lab tests on site, are the way to confirm it. See soil testing and lab values.

For contrast, Hollister, a series associated with Abilene in the same region, is a smectitic Vertisol whose cracks reach more than 30 inches deep and stay open 150 or more days in most years ¹².

What does it mean for foundations?

Edge movement with moisture. Clayey soil shrinks as it dries and swells as it wets, and uneven moisture around a house causes more damage than uniform change ⁴. See perimeter drying settlement and perimeter wetting heave.
Dry climate. With about 26 inches of rain a year ¹, the soil is often dry, so a leak, a sprinkler line or a downspout can create a sharp local wet spot. See leak-induced localized heave.
Flat lots, slow drainage. Slopes are mostly under 1 percent and permeability is moderately slow ¹, so water can sit near the foundation. The ASCE guide recommends sloping soil at least 3 inches in the first 5 feet and discharging downspouts at least 3 feet from the foundation ⁴. See surface drainage and grading.
Carbonate layers. Calcium carbonate accumulations begin within about 10 to 28 inches ¹ and can make the subsoil harder to dig.

Where does Abilene soil form?

Abilene forms on Quaternary terrace deposits in southwestern Oklahoma's Red Plains. See Quaternary alluvium and terraces and the Southwest (Lawton and Red Plains) region page.

Common questions

Where is Abilene soil found?

Abilene is an extensive soil of the Central Rolling Red Plains and Rolling Limestone Prairies of Texas and Oklahoma (MLRA 78). It occurs on stream terrace treads on dissected plains, mostly on slopes under 1 percent.

Is Abilene soil expansive?

Its subsoil is 35 to 50 percent clay with mixed clay mineralogy, so it has clear potential to shrink and swell. The USDA description does not list cracks or slickensides, so lot-specific shrink-swell values should be checked in the Web Soil Survey.

Does Abilene soil contain caliche?

It has calcium carbonate accumulations. Secondary carbonates start about 10 to 28 inches down, and a calcic horizon begins between about 28 and 60 inches.

How well does Abilene soil drain?

It is well drained but has moderately slow permeability, and runoff is negligible to very low on its nearly flat slopes.

Sources

Official Soil Series Description: ABILENE Series USDA Natural Resources Conservation Service
Official Soil Series Description: HOLLISTER 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

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