In the Val d'Hérens there are neither the longest glacier tongues, nor the highest mountain peaks of the Valais. But this valley offers, through its landscapes, glaciers and rivers, and also its flora, extraordinary conditions for the observation of natural processes and landscape changes. The valley reveals to our eyes ideal didactic conditions to study the facts and processes of the recent glacial history. This guide presents a brief introduction to the main elements of glaciology, from ice formation mechanisms to erosion of the bedrock through ice and water. The following chapter focuses on the ancient glaciations and the next one on the imprints left by the warm Middle Ages period and the history of the Little Ice Age.