Prof finds new SA-Uruguay link

2004-05-28 15:19

Tisha Steyn

Cape Town - A Stellenbosch professor has put another piece in the puzzle to prove that, long ago, South Africa and South America were part of one massive landmass.

Professor Reyno Scheepers of the geology department has found rocks at the Postberg nature reserve near Saldanha Bay that are similar to rocks found in Uruguay.

This landmass, which consisted of South Africa, South America, Antarctica, Australia, New Zealand and India, was known as Gondwana, and Scheepers linked 515 Ma old volcanic rocks now occurring on the African and South American continents.

The rocks found at Piriapolis, a holiday town on the eastern coast of Uruguay about 200km northeast of the capital, Monte Video, showed the same textural features and geochemical composition as the ones found at Postberg.

These rocks were formed when riolitic magma erupted in the Postberg area many millions of years ago.

Extinct volcanoes a surprise

Due to the volatile nature of the explosion, an ignimbritic outflow resulted, consisting of a 900°C cloud of gas, rock fragments, pumice and melted silicate material, wiping out everything in a radius of hundreds of square kilometers.

The presence of extinct volcanoes was also a surprise.

Geologists have always believed there wasn't any volcanic activity of this age related to the Cape granite suite along the West Coast, as no evidence, like these rocks, had been found.

The finding is of potential financial value, as certain valuable resources, like gold and copper, may be found where these volcanoes are present.

The presence of the same type of rock in Uruguay proves the theory that the continents are perpetually drifting, as the plates on which the continents rest, keep moving.

- News24