The per ascensum model demonstrates a situation where the water table is relatively close to the surface, allowing solutions to be drawn upwards by evaporation and eventually cement near-surface sediments once they become concentrated enough to trigger precipitation.
This type of system only produces thin duricrust layers since the process ultimately seals the surface horizons, which consequently decreases the potential for further evaporation.
The per descensum model describes a system different from that of the formation of gypcrust in which precipitation of minerals occurs at a depth from downward-percolating solutions.
The bottom layer is the sand rose horizon at the water table where gypsum develops as aggregates of crystals.
[1] Well-cemented gypcrusts may also provide adequate bearing capacity for structures; however, it must be ensured that the underlying uncemented material is not overloaded to avoid collapse.