My research interests are interdisciplinary, at the interface of Quaternary science (palaeoclimatology and geochronology), hydrogeology and geomorphology. I am interested in understanding the nature and impacts of past hydroclimatic and environmental change and the mechanisms of global climate forcing, with a focus on deserts and drylands over timescales of glacial-interglacial cycles down to recent decades. My current projects fall within two main themes:
Chemical tracers as novel proxies for environmental change and records of groundwater recharge and quality
This research concerns developing the use of chemical tracers and isotopic signals proxies in dryland sediments and groundwater as novel proxies for past environmental conditions. The portion of sediment of particular interest is that part above the water table, known as the unsaturated zone (USZ) (or vadose zone), because it has the potential to store records of decadal-scale resolution. Reconstructing rainfall fluctuations and moisture availability in drylands is challenging, which makes the USZ and groundwater extremely valuable key archives. The main goals of this research are to: (i) characterise the chemical signature that establishes in the near-surface zone of the USZ and explore the transport of this signal down through the USZ, which yields a ‘hydrostratigaphy’, (ii) assess the extent to which hydrostratigraphies may be used as indicators of past environments, and (iii) apply the information that hydrostratigraphies contain about land-use change through the influence land-use change has over infiltration/recharge rates and the quality of the infiltrating water.
Quaternary dryland environmental dynamics
The nature and timing of landscape dynamics during the Quaternary complements and extends the hydrostratigraphy approach by seeking to understand how whole landscapes respond to the hydroclimatic fluctuations. The overarching aim is to elucidate the nature of the climate of the past in African and Arabian drylands, asking what controls the nature of hydroclimatic change and variability between the last interglacial and glacial and on into the Holocene. By understanding the complex nature of dryland landscape and environmental response to climatic forcing, we provide a scientific basis to facilitate realistic projections of future climate change within these environmentally sensitive regions of the world.
Within southern Africa, I work on reconstructing dunefield landscapes within the Namib Sand Sea and the Kalahari, and interdigitated water-lain interdune deposits in the former. Geochronology is key to reconstructing these past changes, and my major method in this context is luminescence dating. I am developing the use of portable luminescence readers to aid with rapid age assessment out in the field.
I am analysing the tufa carbonate in Wadi Dabsa in the Harrat Al Birk in south west Saudi Arabia, as part of the SURFACE Project. This explores the surface Palaeolithic archaeological record of Saudi Arabia and asks what drove hominin dispersals out of Africa. I am analysing the setting, morphology, stable isotopic composition and U-Th ages of tufa carbonates, which provide evidence for wetter conditions in the landscape that provided water and potentially prey for early hominins. A lithic assemblage is found in association with these units of tufa carbonate, and the geoarchaeological context of these lithics is being investigated by PI Dr Robyn Inglis and a wider team.
I am collaborating with the NERC U-Th facility at Keyworth, as PI, funded by a grant-in-kind from the Isotope Geosciences Facilities (£97,500) that takes a multi-method approach, also constraining the age of basalt lava flows (40Ar/39AR), which interact with the surface and subsurface hydrology of the basin in which the tufa carbonate has accumulated.