Climate and Nile floods in ancient Egypt: Insights from the isotope composition of freshwater shells and geochemistry of Saqqara-Memphis floodplain, Egypt

Abstract

We report the geochemical composition of a 13 m deep core (Core SAQA 22) drilled in the Saqqara-Memphis floodplain, as well as the isotopic ratios (δ¹³C and δ¹⁸O) of freshwater Corbicula shells. Core SAQA 22 consists mainly of Middle - Late Holocene floodplain sediments (units II-VI) that unconformably overly Late Pleistocene sand and gravel (Unit 1). The findings show variations in δ¹⁸O and δ¹³C values, suggesting intermittent periods of high evaporation/precipitation ratios and moister environments during the Middle Holocene. Due to the prevalence of dry conditions than what exists today, the δ¹⁸O enrichment and mild δ¹³C depletion in the upper part of the core point to less productive paleoenvironments during the Late Holocene. The consecutive climatic variations experienced in ancient Egypt, as deduced from the Saqqara-Memphis floodplain, are outlined as follows: (1) the Predynastic period (7–5.2 kyr cal BP) is generally wet; (2) the Old Kingdom (5.2–4.2 kyr cal BP) had dry local climate conditions for the first half of its existence, which later became wetter during the Late Old Kingdom; (3) the Old Kingdom ended with a brief period of aridity; (4) the Middle Kingdom (4–3.7 kyr cal BP) had a local climate that was both moist and wet, with a brief dry phase at the end; (5) the New Kingdom ended with dry conditions; (6) the local climate turned arid after the Late Period (3–2.3 kyr cal BP); (7) an arid climate was established in the Nile Basin after 2.7 kyr cal BP, with notable drought periods at 1.2 and 0.6 kyr cal BP.