East of the Estancia Basin escarpment, New Mexico flattens out dramatically onto the High Plains. Clovis, Portales, Tucumcari — the horizon is wide and the terrain is nearly level. The soil here is the Blackwater Draw Formation: wind-deposited material, mostly silts and clays, that accumulated over tens of thousands of years. The playas — shallow closed depressions — are scattered across the landscape. They fill briefly after rain and drain by evaporation. They are also where the heaviest clay concentrations settle out over time.

The Blackwater Draw Formation contains smectite clays that shrink and swell with moisture changes. The High Plains receives erratic rainfall, and the playas concentrate moisture in ways that produce local wet-dry cycles more extreme than the surrounding ground. Foundations on or near playa margins see the most movement. Closed drainage means moisture does not run off — it stays in the soil or evaporates. In the Clovis area, the combination of expansive soils and a shallow water table in some areas creates conditions where the soil never fully dries out, keeping it in a near-saturated expanded state.

The Pecos Valley is productive agricultural country — dairy operations, alfalfa fields, orchards in the Roswell area. The surface soil is productive and has been irrigated for over a century. Below it, the Permian evaporite formations — gypsum, anhydrite, halite — are close to the surface in places and deeper in others. The landscape gives no indication of what is happening underground. Carlsbad Caverns is the most visible expression of what this geology can do when water and time dissolve the evaporite rock, but the same process operates on a smaller scale throughout the valley.

Subsurface dissolution of evaporite minerals creates voids that can cause foundation settlement — gradually as the void grows, or suddenly if the roof of the void collapses. The risk is not uniformly distributed; it is highest where the evaporite formations are close to the surface and where groundwater or irrigation has introduced sustained moisture. Century-long irrigation in the Roswell and Carlsbad areas has altered subsurface moisture conditions significantly from natural baseline. Foundations that were stable for 50 years can begin moving as dissolution progresses.

Deming sits in the middle of a dry agricultural plain that, until recently, was intensively irrigated from the Mimbres Valley aquifer. The soil is pale and alkaline — caliche is visible in any excavation, and the surface has a bleached look in places from salt accumulation. Silver City to the north is on different terrain entirely — older, harder formations in the upper Mimbres drainage with a mountain-town character. The two communities are in the same basin geologically but present different foundation environments.

In the Deming area, decades of aquifer pumping have removed water from the subsurface, allowing compressible sediments to consolidate under their own weight — a process called aquifer compaction subsidence. This produces gradual, relatively uniform ground settlement across large areas. It is slow and often goes unnoticed until the cumulative effect becomes visible in foundations and infrastructure. The buried Lake Palomas lacustrine clays in the deeper subsurface are expansive and complicate the picture. In Silver City, the upper Mimbres drainage terrain introduces shallow rock and mine-related subsidence in older areas of the community.

Lordsburg is a small community at the junction of I-10 and the old Route 66 country, surrounded by bajada terrain — the broad alluvial aprons that grade from the surrounding mountain ranges down to the basin floor. The soil on the upper fans is loose, granular, and collapsible. Lower on the fan and in the basin floor, finer-grained material accumulates with more clay content. The Animas Valley to the south is even more remote — ranching country where foundation problems tend to go unaddressed for years before anyone calls.

The upper fan alluvium is collapsible under first wetting — the same mechanism as the Jornada del Muerto and other dry alluvial basins in southern New Mexico. Hydrocompaction is the mechanism. Lower fan and basin floor material has higher clay content and some expansive potential, but the primary hazard in Lordsburg is collapsibility on the fan surfaces where most development sits. The Gila River floodplain at Virden is a different environment — floodplain clays with overbank deposits that respond to the river's wet and dry cycles.