Click to enlarge. Regosols are weakly developed soils to meet the classification requirements of other soil orders. They lack a recognizable B horizon (i.e., B horizon is less than 5 cm thick). Soils of the Regosolic order are most commonly associated with landforms where the land surface is (or has recently been) unstable. Because of the unstable surface, the soil has had little time to develop. Consequently, soil horizons are very weakly expressed if present at all.