Meaningful construction of site categories requires a combination of quantitative measures and qualitative assessment based taphonomy and other formation process issues. In the loose volcanic soils of the Upper Colca, relatively high erosion rates result from downslope movement and stream-channel migration, combined with wind deflation and seasonally-intense precipitation. For example, high density lithic loci are commonly found at the base of slopes due to the disturbance and erosion that are part of site formation processes (Rick 1976;Schiffer 1983). These artifact aggregations at the bottom of hill-slopes may appear to qualify as high-density loci when assessed quantitatively and through sampling, however a qualitative interpretation of the context reveals the formation processes at work.

In the Upper Colca project area anthropogenic effects, due to a high incidence of site reoccupation, include the direct and indirect effects of the later reuse of space. These include palimpsests, site maintenance and disturbance, interments, and reuse of construction materials for residential or mortuary structures. The indirect effects are primarily the result of intensive pastoral production that occurred in the Upper Colca in the last few millennia. These include erosion and trampling (although camelids have two digit pads instead of hoofs), and landscape modification for pastoral production such as corral construction and the modification of water distribution to enhance grazing opportunities at bofedales.