Within my research into the dynamics of dryland environments over Quaternary and recent timescales I have two current research projects:

1) Chemical tracers in the unsaturated zone (USZ) as novel archives

Palaeomoisture records in sandy deserts

With Mike Edmunds, I am reviewing the application of, and developments of, using chemical proxies in sand dune sediments (the unsaturated zone) as novel proxies for past moisture availability.

Rainfall in the Desert Sand

RGSbadgeWith the 2010 Thesiger-Oman International Fellowship from the Royal Geographical Society I samples sediment from linear dunes above the Stampriet Aquifer in southern  Namibia to investigate rates of recharge through the sands to groundwater. The results produce a recharge record that covers the past five decades and records fluctuations in moisture availability during this period. Read RGS research report, and associated publication ‘Sand, salt and water in the Stampriet Basin, Namibi: calculating unstarated zone (Kalahari dunefield) recharge using the chloride mass balance approach’ in Water SA 38(3), 367-377 (email me for a copy). This first phase of research was also supported by a small research grant from the British Society for Geomorphology .

GW nitrate in Sn AfricaIn the process of investigating chloride mass balance we (my collaborator is Prof. Mike Edmunds) discovered elevated concentrations of nitrate in some of the profiles. There is good evidence to suggest this is naturally-produced and in a locally heterogenous, or patchy, manner. This significant pool of nitrate in the unsaturated zone is moving through the profile and contributing to baseline nitrate in the Stampriet Basin groundwater. Elevated groundwater appears to be typical of many dryland settings but remains difficult to manage.

The second phase of this fieldwork was undertaken in April 2013 and investigates whether the geomorphic setting of the dunes, in relation to a shallow pan, influence the USZ record. The fieldwork was funded by the Quaternary Research Association.

2) Quaternary environmental dyanmics using geoproxies

Attempting rapid age assessment of dune sediments in the Namib Sand Sea portable reader
Using a portable luminescence reader (pictured) I am producing a simple calibration between the portable reader signals and full OSL dating using the established dating protocol so that portable reader measurements taken in the field could in a few minutes give a rapid (albeit rough) estimate of age. I am working on the luminescence aspect with Prof. Mark Bateman at the University of Sheffield and in collaboration with Prof. Dave Thomas at the University of Oxford and other members of the former Sand Seas and Dune Fields working group, to aquire further samples.

transect M13This started with a comparison of portable reader and full OSL dating for near-surface samples taken by Dave Thomas along a transect across a linear dune in the south of the Namib Sand Sea. The portable reader reveals important geomorphic information about recent sediment movement at the crest and relative burial ages of different parts of the dune flanks and interdune sediment.

correlationThis developed into a project to testing the potential of the portable reader to distinguish between samples of different sediment burial ages in the Namib Sand Sea. The first site is the Holocene age samples from the dune transect above and the second site is a dune flank at a site Narabeb, in the north of the sand sea, where samples ages centre on 110,000 years. (see this paper in PPP on this Narabeb site and others in the northern Namib Sand Sea).

Casting new light on Quaternary environmental change in the Namib Desert.




Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s