Chronologies and palaeoenvironments of the western Nefud Desert, Saudi Arabia over the past 500 ka

Orbitally-driven humid phases in arid regions such as the Arabian and Saharan Deserts have played an important biogeographic role in ancient human dispersals, range expansions/contractions and population structure. The timing and regional climatic pattern of humid phases has been shown by multiple long-term continuous palaeoenvironmental records from both marine and terrestrial (speleothems and long palaeolake cores) archives. However, these records lack detailed information at the scale at which humans interact with the environment, meaning these interactions are poorly understood. To address this, this thesis applies luminescence dating alongside multi-proxy palaeoenvironmental analysis to carbonate/siliceous sediment beds preserved in interdunal depressions in the western Nefud Desert, Saudi Arabia. While these deposits are short relative to many marine, speleothem and palaeolake records, they provide “snapshots” of the palaeoenvironmental conditions experienced by ancient humans. Importantly, these deposits are often directly associated with Lower and Middle Palaeolithic archaeology, fossils or footprints demonstrating they were an important locus for ancient human activity during humid phases.

The luminescence dating demonstrates that carbonate/siliceous sediment beds most likely formed during humid intervals that occurred during warm marine isotope stages or sub-stages over the past c. 500,000 years, with the exception of the Holocene. Multi-proxy analysis reveals that the carbonate/siliceous sediment beds consistently represent perennial but shallow freshwater interdunal lakes, irrespective of the time-interval they formed in. This thesis therefore argues that the western Nefud Desert, within the continental interior of the Arabian Peninsula, has repeatedly provided perennial freshwater resources for ancient humans and other fauna over the past c. 500,000 years. This may have enabled multiple pulses of hominin dispersals into the Arabian Peninsula over the past c.500,000 years.