Why Foundations Move in the Memphis Region

Much of Memphis and the bluff line sits on loess — fine, wind-deposited silt. It is stable when it stays at a consistent moisture level and it will hold a near-vertical cut when dry.

Its weakness is concentrated water. A downspout discharging at the foundation or a channel of runoff will erode loess quickly and can undermine footings, stoops, and walkways.

East and south of the loess cap, high-plasticity clays dominate. They take on water in spring and swell; they dry in July and August and shrink, opening shrinkage cracks in the yard you can put your hand into.

A foundation sitting on that soil rises and falls with it. Because moisture never changes uniformly around a house, the movement is differential — one corner moves more than another — and the structure has to absorb the difference.

West of the river, Crittenden County and the Arkansas Delta sit on deep alluvial deposits laid down by the Mississippi. These soils are soft, layered, and often carry a high water table.

Movement here tends to be slow consolidation under load rather than dramatic seasonal swings, and competent bearing material is typically deeper — which is why pier depths in the Delta usually exceed those in eastern Shelby County.