 The series documents the gradual leveling of a mountain (called Tahualtapa in the Cahuilla language) in what is now called San Bernardino County through a series of photographs whose frames are filled with materials relating to the mountain's history such as feathers, marble, and cement.DeSoto also began transitioning from photography to installation via works such as the "Site Projects" (1980-1986), which combined large-scale manipulations and "non-destructive" interventions in the actual landscape reminiscent of Robert Smithson with long camera exposures documenting the temporal changes in each work.DeSoto's installation works have typically made extensive use of manipulated recorded sound, with an emphasis on using directional speakers and projected imagery to create an evocative environment.