Slickensides and Vertisols
3.4.5.4.1 Vertisols: Slickensides and gilgai
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slickenside in shovel
slickenside in situ
Notice the angles in the images above, and the smooth, pressured faces.  These are slickensides at their strongest expression.  This one came out as a single unit. This is the spot from which the slickenside at left was removed.  Again, notice the angles that are present.  Things are not running vertically and horizontally.
water-filled gilgai
leaning power poles
The gilgai in this recently burned CRP field near Temple, TX filled with water, showing the regular polygonal pattern associated with the gilgai of that soil, the Houston Black clay. Vertisols play havoc with fence posts, power lines, etc.  The shrink-swell processes cause them to shift from their initially vertical positions.
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slickenside in situ
intersecting slickensides
This is another slickenside in place.  Once the soils dry, the slickensides break up and disappear as the soil shrinks and cracks. Notice the angles in this Vertisol.  Nothing is running exactly horizontally.  These intersecting angles and slickensides (under each of the cracks you can see) are characteristic of Vertisols.
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