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24 October 2018
Geologist shares ground-breaking findings at Alex du Toit lecture
From the left: Prof Marian Tredoux, Associate Professor in the UFS Department of Geology, Prof Lew Ashwal, and Snegugu Zigubu, BSc (Hons) Geology student.

The Department of Geology at the University of the Free State (UFS) was recently the host of a lecture in the 2018 Alex du Toit Memorial Lecture series.

The speaker at this event was the A-rated NRF researcher, Prof Lew Ashwal from the University of the Witwatersrand. He addressed academics and geology students on ‘Wandering continents of the Indian Ocean’.

Lost continent found


In this talk he specifically shared the research he conducted on the islands of Madagascar (which he visited 30 times to conduct field work and says it is not for the faint-hearted), the Seychelles, and Mauritius. 

Two things stood out in his lecture: the way in which his findings on the three islands helped to refine details about the assembly of the Gondwana supercontinent, and the report of a ‘lost continent’ found under Mauritius. 

These discussions were linked by Prof Ashwal’s belief that the so-called lost continent he found under Mauritius is a leftover from the break-up of Gondwana,

The discovery was made when he and a team of researchers found zircon from 2000 million years ago on a 9-million-year-young island. He believes that the piece of crust (where the tested zircon probably formed), which was covered by lava during recent volcanic eruptions on the island, is a tiny piece of the ancient continent which broke off from Madagascar, when Africa, India, Australia and Antarctica split up and formed the Indian Ocean.

Media frenzy 

The fact that the team of researchers found these extremely old minerals proves that there are materials under Mauritius that originated from a continent under the island. 

Prof Ashwal is studying the break-up process of the continents in order to understand the geological history of the planet.

For his work Prof Ashwal has enjoyed coverage from publications as far apart in focus from each other as The New York Times and Cosmopolitan magazine. 

News Archive

Water erosion research help determine future of dams
2017-03-07

Description: Dr Jay le Roux Tags: Dr Jay le Roux

Dr Jay le Roux, one of 31 new NRF-rated
researchers at the University of the Free State,
aims for a higher rating from the NRF.
Photo: Rulanzen Martin

“This rating will motivate me to do more research, to improve outcomes, and to aim for a higher C-rating.” This was the response of Dr Jay le Roux, who was recently graded as an Y2-rated researcher by the National Research Foundation (NRF).

Dr Le Roux, senior lecturer in the Department of Geography at the University of the Free State (UFS), is one of 31 new NRF-rated researchers at the UFS. “This grading will make it possible to focus on more specific research during field research and to come in contact with other experts. Researchers are graded on their potential or contribution in their respective fields,” he said.

Research assess different techniques
His research on water erosion risk in South Africa (SA) is a methodological framework with three hierarchal levels presented. It was done in collaboration with the University of Pretoria (UP), Water Research Commission, Department of Agriculture, Forestry and Fisheries, and recently Rhodes University and the Department of Environmental Affairs. Dr Le Roux was registered for 5 years at UP, while working full-time for the Agricultural Research Council – Institute for Soil, Climate and Water (ARC-ISCW).

Water erosion risk assessment in South Africa: towards a methodological framework
, illustrates the most feasible erosion assessment techniques and input datasets that can be used to map water erosion features in SA. It also emphasises the simplicity required for application at a regional scale, with proper incorporation of the most important erosion-causal factors.

The main feature that distinguishes this approach from previous studies is the fact that this study interprets erosion features as individual sediment sources. Modelling the sediment yield contribution from gully erosion (also known as dongas) with emphasis on connectivity and sediment transport, can be considered as an important step towards the assessment of sediment produce at regional scale. 
 
Dams a pivotal element in river networks

Soil is an important, but limited natural resource in SA. Soil erosion not only involves loss of fertile topsoil and reduction of soil productivity, but is also coupled with serious off-site impacts related to increased mobilisation of sediment and delivery to rivers.

The siltation of dams is a big problem in SA, especially dams that are located in eroded catchment areas. Dr Le Roux recently developed a model to assess sediment yield contribution from gully erosion at a large catchment scale. “The Mzimvubu River Catchment is the only large river network in SA on record without a dam.” The flow and sediment yield in the catchment made it possible to estimate dam life expectancies on between 43 and 55 years for future dams in the area.
 
Future model to assess soil erosion
“I plan to finalise a soil erosion model that will determine the sediment yield of gully erosion on a bigger scale.” It will be useful to determine the lifespan of dams where gully erosion is a big problem. Two of his PhD students are currently working on project proposals to assess soil erosion with the help of remote sensing techniques.

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