The effects of acid deposition on the sandstone masonry of Anasazi cliff-dwelling ruins at Mesa Verde National Park, Colorado, are being investigated. Potential correlations are sought between surface erosion rates and continuously monitored aerometric parameters. A mechanism of deterioration by acceleration of natural erosion processes is hypothesized. Gaseous and particulate pollutant concentrations and meteorological variables are measured at Spruce Tree House ruin. Deterioration of the stone occurs by a combination of chemical and mechanical processes which weaken the material which bonds the quartz grains. The monitoring scheme is discussed in the context of ongoing research.