Edited by A. Elena Charola, Robert J. Koestler e Gianni Lombardi.
The petrographic and petrophysical features of lavas and volcanic tuffs are very heterogeneous. They depend on the original volcanic facies, their evolution during cooling, and the geomechanical stresses during movement. Natural outcrops undergo weathering during the course of geological time; the causes and results are varied. Weathering also operates on objects fashioned from these materials when the objects are left exposed to open air. This process is mainly dependent on climatic and microclimatic factors, since they control the hydrochemical and biochemical parameters. The role played by marine sprays is emphasized. Technology transfer from previous studies has permitted development of a specific methodology to study volcanic materials in general and Easter Island statues in particular.