The geology of North Texas is quite diverse as evidenced by the diagram below. Each swath of color represents a different geologic formation. The geologic formation that underlies your home will dictate the soil type your house rests on as well as local drainage patterns.
The soil that underlies the area is of particular importance. The soil that underlies the area can range from sandy soils to clay soils. Clay soil types are predominating in the region and will shrink and swell with moisture gains and losses. Sandy soils on the other hand will shrink and swell very little but are prone to erosion and sub-surface migratory water due to their larger particle size.