No / This paper introduces a method to study the degree of change that affected a prehistoric context as the result of environmental processes. It is based on the direct examination of a representative sample of stone tool by-products, and on the identification of all surface alteration features. We summarize the theoretical bases for the formation of some wear features and the main results of a number of experiments involving interaction between chert flakes and sediments. Experimental results include: (1) the wear rate of flakes is not constant; (2) the wear rate increases as the size of the grains that compose the matrix increases; (3) fine grained chert resists wear better then coarse grained chert; and (4) the presence of moisture will trigger some chemical reactions that promote wear and the formation of films on chert surfaces. We apply these findings to the cave site of Grotta di Pozzo, Italy, and conclude that, strictly within the area sampled, there is low degree of disturbance and low intensity of chemical processes that may, however, confound the reconstruction of human activities in this part of the cave.