The occurrence of stratification and layering in the transition region of the lower atmosphere during nighttime is a persistent feature, particularly over complex terrain. The evolution of these layers was studied during the Vertical Transport and Mixing (VTMX) field study in Salt Lake City, UT during Oct 2000 using a minisodar, a single-axis vertically-pointing low frequency sodar, a radar and a tethered balloon system. Because the instruments were located along the eastern edge of the urban basin, between ParleyÕs Canyon and Big Cottonwood Canyon outflows, winds were relatively light, which permitted frequent balloon flights to heights of 500 m or more during ten intensive operating periods. Stable layers detected principally from sodar signal returns were used to vector the tethered balloon through and near regions of interest. More than 200 profiles through stratified layers were used to investigate the possible relative roles of moisture, wind speed, and wind direction, in addition to temperature in the evolution of these elements. In most cases a relative maximum in moisture is found to be associated with the stratified layers (whose depth is often less than 20 m); however, the magnitude of the variations, in both temperature and moisture, was often quite small, characteristic of the transition region.