The soils of many areas of Nevada are derived from volcanic and plutonic rocks and commonly contain a high percentage of clay. Some clays such as montmorillonite swell when wet and can cause structural damage to buildings with improper foundations. Except for the mapping of the Quaternary geology, NBMG deals little with the specifics of soil. The Information Office has an incomplete set of the soil surveys published by the Natural Resource and Conservation Service (NRCS) of the U.S. Department of Agriculture), which discuss the clay aspects of the soils in the areas covered. If you have concerns about the swelling potential of soils in a given area, you should check with the local county or city engineer or hire a consulting geologist or engineering firm to conduct a study.