This paper is mainly based on the handbook written by Dr. Taylor (198 7) on radiocarbon, which is still in force despite of the years. lt does not covers all the literature, but quotes sorne basic texts as refe­rences. The second part of the text, which is shorter and complementary to the first, is an exercise of calibration on a an eposide of andean archaeology, as a means to evaluare the importanc of examining past events on calendar years instead of radiocarbon ones. The final aim of this essay is to motivare students to apply calibration in their research, as well as in their thesis and monographic works, in arder to start evaluating our history on the basis of astral years and not only radiocarbon ones, which is currently the usual approach.

A labor research of a lithic series from two archaeological sites located at the Chusqui District (Ayacucho) revealed the occurrence of true blades of basalt and quartz sandstone that were associated with sherds of both Early Intermediate Pe-riod and the Middle Horizon (ca. 0-900 AD). In this report we present the results of the examination of this series by stressing out some key and relevant data like the preparation of the blade cores from which blades were removed as well as the skills of the flintknappers applying this kind of rare recorded lithic technology yet not for that reason less important.