Vesicular pores
As the soil rapidly dries and hardens in arid environments, air bubbles get trapped below sealed surfaces, forming vesicular pores. Vesicular pores are a common feature (but not diagnostic) of the Pedaric great groups of Chromosols, Dermosols or Sodosols. They may be found in A horizons near the surface or on the underside of any surface flake. They are also less commonly found in other subgroups of these soil orders.
Example of vesicular pores