Patina and Environment in the Wadi al-Hayat: Towards a Chronology for the Rock Art of the Central Sahara

Abstract

This paper proposes a broad chronological framework for the engravings of the Wadi al-Hayat that is based on environmental parameters rather than stylistic observations. During the Holocene, the climate of the central Sahara changed from savanna to desert. This environmental background informed the experience of the engravers and underpinned the weathering of rock surfaces. To establish a link between images and climatic sequence, 2,466 individual animal engravings were analyzed with regard to the depicted species, patina and the location of the panel in relation to the dated shorelines of the al-Hayat palaeolake. Based on their patina, engravings are grouped into a broad, four-stage chronological sequence. The chronological relevance of this framework is tested in three different ways. The dates and sequence of the introduction of domestic animals match their depiction across the four engraving groups. The habitats of the depicted wild animals reflect a dramatic change from savanna to desert that is consistent with climatic records and the physical process of the patina formation. In addition, Early and Middle Pastoral engravings are shown to be in locations that correspond to the high lake levels of the African Humid period. Late Pastoral and Garamantian engravings are also recorded in areas that only became accessible once the palaeolake had dried up. Although the proposed methodology cannot provide precise dates for individual engravings, it can be used to establish a broad chronological framework that allows us to place the rock art within its archaeological context.