Clay-rich soils that shrink and swell with changes in moisture content.

This shrink/swell action creates serious engineering problems and generally prevents formation of distinct, well-developed horizons.





Utah Vertisol


Cracks can be wide enough to make the terrain treacherous for animals.

Note film box for scale.

Surface material accumulates in these cracks during the dry season and are "swallowed" by the soil in the wet season.

This creates a self-mixing action.




Gulf Coast Prairies, Texas Vertisol


  • very deep
  • well drained
  • very slowly permeable
  • clayey sediments

Formed on flat coastal plains.

Cracks are 1/2 to 2 inches wide and up to 4 feet deep.

Water enters rapidly when soil is dry but very slow when wet.

Used for cropland and rangeland.

Crops include:

  • corn
  • cotton
  • rice



Vertisol Slickenside


Slickensides are polished, grooved surfaces that occur along shear planes within the soil.

These shear planes result from the shrink-swell action of clays.




Cracked Wall On Vertisol


Vertisols present unique engineering difficulties, due to their high linear extensibility.

Special designs are necessary to avoid structural damage to buildings and roads.

Structures can be built on slabs of concrete that float in the soil.

Gravel placed around foundations may provide a buffer from shrink/swell.

Pilings can be used to anchor a foundation on a more stable base.

Other strategies include minimizing shrink/swell action by maintaining a relatively





Gilgai, South Dakota


Natural soil formation of small knolls and basins found in expanding-contracting clay soils.

The micro-ridges and micro-valleys are oriented in the same general direction as the slope.




Texas Gilgai

Micro-ponds are more common on nearly flat topography.




Sachse, Texas Gilgai


10-acre gilgai feature.