PEOPLE

Hannah Walford
PhD Research Student



Research Profile

Current interests:

Africa is unusual in that it is almost entirely surrounded by passive continental margins. Large thicknesses of sediment (up to ~10km) have accumulated on the continental shelf at the sites of major deltas and have remained largely undisturbed throughout the Cenozoic. The offshore stratigraphy provides an indirect record of the pattern of vertical motions onshore, as variations in sediment flux to the shelf reflect tectonically driven topographic changes in the catchment area. Half of Africa is drained by just ten rivers, so by analysing the major deltas the drainage history of much of the continent can be reconstructed.

The framework of onshore vertical motions has been identified using subsidence modelling (in one- and two-dimensions), unconformities and the geomorphological literature. Isopach maps of solid grain sediment thickness have been generated at several major deltas. It is noted that periods of rapid uplift and denudation (typified by the dramatic gorge-cutting in southern Africa during the late Cenozoic) coincide with periods of increased sediment flux to the offshore.

Africa differs from other continents in that many of its important geological features are thought to be dynamically supported by mantle convection. The pattern of convection is visible as long wavelength gravity anomalies, which coincide with features such as the Hoggar and Tibesti massifs, and the Congo Basin. By looking for relationships between the distribution of sediment and the pattern of convection, the contribution of mantle convection to drainage development and continental topography can be quantitatively assessed.



Education

University of Cambridge: 1999-
PhD Title: "The relationship between subsidence, topography and gravity in Africa"

University of Cambridge (Newnham College) 1995-1999
BA/MSci Geological Sciences
MSci research project title: "Subsidence analysis and sediment flux of the Mozambique region"



Publications

  1. H.L. Walford, L.M. Mackay & N.J. White (2003?) Subsidence analysis of African Sedimentary Basins. Submitted to Tectonics
  2. H.L. Walford, N.J. White & J.C. Sydow (2003?) Sediment flux history of the Zambezi delta, Mozambique. About to be submitted.


Presentations

  1. H.L. Walford. Mantle convection and subsidence beneath Africa. Poster T22B-06. AGU Fall meeting 1999.
  2. H.L. Walford. Sedimentation, vertical motions and mantle convection on the African continent. PESGB Conference at the Geological Society, London. "New insights into basin studies from collaborative research". March 15th 2001.
  3. H.L. Walford & N.J. White. Sedimentation, vertical motions and mantle convection on the African continent. AAPG Annual Convention 2001.