Blue Nile’s source to reveal its dark secrets

A team of scientists from St Andrews and Wales are set to make an important contribution to understanding what caused the collapse of one of the World’s great dynasties around 4200 years ago, that of the Egyptian Old Kingdom.

It is widely believed by Egyptologists that the demise of the Old Kingdom was triggered by drought caused by a sudden and unanticipated reduction in the Nile floods over a period of two or three decades. This led to a period of famine, political crisis and war. Other scientific studies have shown a short-lived but pronounced decline in rainfall and reduced water flow around 2150 BC over an area that extended from Tibet to Italy.

Led by Dr Henry Lamb from the University of Wales’ Institute of Geography and Earth Sciences in Aberystwyth in conjunction with Dr Richard Bates of the University of St Andrews’ School of Geography and Geosciences, the team will travel to Lake Tana, source of the Blue Nile, in October 2003.

Located in northern Ethiopia, Lake Tana extends over an area of 3000 km2 but has maximum depth of only 14 metres. The lake’s only outflow is the Blue Nile, which provides most of the water that flows down the Nile. Almost all of the sediments formerly deposited on the banks of the lower Nile, (the building of the Aswan dam means that sediments no longer reach Egypt) originated in the Ethiopian highlands.

Dr Bates will undertake a seismic survey of the lake using state of the art, very high resolution acoustic sensors. The acoustic sensors send out very high resolution sound pulses that will penetrate the lake bottom and bounce off layers in the lake sediments.

Dr Bates said, “From an analysis of these results, I will be able to determine not only the thickness and distribution of sediment type but also be able to indicate a sequence of sedimentation that can be related to previous climate change events and their influence on changes in lake depth and area. If the lake ever dried up completely, the images should show a formerly dry bed covered by younger sediments. These results will be used to help locate the core locations. This type of high resolution geophysical investigation follows on from work that has been conducted in Loch Sunart and the Tay Estuary over the last couple of years for which the School is acquiring a considerable reputation. It is my hope that through projects such as these we will be able to not only further our understanding of climate change impacts but also that we will be able to build up the tools necessary to conduct this work, tools that are currently not available to researchers in Scotland.”

Meanwhile, Dr Lamb said, “Most of the large equatorial lakes that feed the White Nile have been studied in detail. This will be the first such study of Lake Tana, whose waters helped provide such a stable and fertile environment for the great Egyptian dynasties which thrived on the banks of the Nile. Our aim is to build up an historical picture of climate change at Lake Tana, which, due to its relative shallowness, is particularly sensitive to changes in rainfall.”

Once back in Aberystwyth, the cores of the lake bed will be analysed. The team will be looking for a range of indicators that will reflect climate conditions at any given time. Diatoms, a type of microscopic algae that are very sensitive to water chemistry, will indicate past water salinity. Low salinity means a time of relatively high rainfall, while past drought should be have caused increased salinity. Pollen and oxygen isotopes will also reveal information about the climate.

Dr Lamb continued, “The data gathered from this study should reveal a profile of changes in the lake’s water levels. We will be able to confirm whether the collapse of the Egyptian Old Kingdom coincided with a drought. We should also be able to answer a number of other questions such as was Lake Tana dry at the same time as Lake Victoria between 16,000 and 14,000 years ago, and does the lake-sediment record correlate with variations in the flow of the Nile.”

The work is being funded by two grant awards that have been made to Dr Lamb and Dr Sarah Davies at the University of Wales, Aberystwyth and Dr Bates at the University of St Andrews. The sum of £69,070 has been awarded by the Leverhulme Trust and the sum of £30,335 has been awarded by the Natural Environment Research Council.

ENDS

Further information:

Dr Henry Lamb, Institute of Geography and Earth Sciences, The University of Wales, Aberystwyth Tel: 01970 622597, [email protected]

Dr Richard Bates, School of Geography and Geosciences, University of St Andrews. Temporary contact details – Center for Coastal and Ocean Mapping, University of New Hampshire, Durham, NH 03824, USA – work: 603 862 0564 fax: 603 862 0839 home:401 364 6838 email: [email protected].

Arthur Dafis, Public Relations Officer, The University of Wales, Aberystwyth. Tel: 01970 621763 E-mail: [email protected] Mobile: 07811 412 295

The Leverhulme Trust The Leverhulme Trust was established in 1925 under the Will of the first Lord Leverhulme – William Hesketh Lever – the entrepreneur and philanthropist who established Lever Brothers in the late nineteenth century. The Trust provides some £25million each year to promote research of originality and significance principally in the university sector across a full span of disciplines. (For further information, please see www.leverhulme.org.uk)

Issued by Beattie Media on behalf of the University of St Andrews For more information please contact: Claire Grainger on 01334 462530, 07730 415 015 or email cg24@st- andrews.ac.uk View University press releases on- line at http://www.st-andrews.ac.uk Ref: richbates/standrews/chg/3april2003