Why is Africa so high and when and how did it get up there?

Some of the most influential literature and ideas on how continental topography is formed and evolves over geological time originated from work in southern Africa. However, after more than 100 years the debate, often controversial, and intellectual wrangling over how fast, when and why the topography of this continent evolved to produce the classic present escarpment morphology still rages–even more vigorously than ever it seems. The resurgence in interest has arguably been stoked, not by field geomorphology as was the focus in the last century, but by major advances in seismology and geodynamic and surface process modelling capacity and sophistication. This work has focused on the properties and behaviour of the deep mantle beneath southern Africa and whether the mantle has anything at all to do with Africa’s unusually high topography. If anything, this has caused even more dissent and argument though. This dissent is fuelled by significant uncertainties concerning the physical properties of the mantle (e.g. density, both actual and structure, viscosity, thermal structure and how these relate to seismic velocity specifically) as well as fundamental philosophical and technical differences in the way geodynamic models are constructed and parameterised. This seminar will look at the available “evidence” that might be available to us to help constrain these models and will attempt to highlight the “common ground”, so to speak, between opposing ideas. This will involve a great deal of “thinking aloud” about how different possible geodynamic mechanisms may be expressed in the history of landscape evolution as seen from the surface, and where there may be opportunities to resolve the key points of difference between opposing hypotheses.