18.0 Dr. Hans Merensky. The world’s greatest geologist

(Look Beyond the Wind by Olga Lehmann)

When Dr Hans Merensky returned to South Africa after studying geology in Germany he went for a holiday in South West Africa (now Namibia). Whilst there, railway workers discovered a diamond in a new cutting near Swakopmund. Merensky went to look and found a seam of 185 Ma fossilized oyster shells which Witwatersrand University identified as warm water oysters. This led him to propose that there were undersea volcanoes that warmed the water and spewed up the diamonds. He was right about volcanoes as the mid-Atlantic Ridge as was close by then! After he became well off and famous for his platinum reef and chrome discoveries in the Bushveld Complex he returned to South West Africa to look for the Oyster Line near the Orange River. Here, about a kilometre in from the sea he found the rich seam of alluvial diamonds.

The Earth’s crust had split along that coastline about 185 Ma leaving a warm sea as it was shielded by the new continent of South America. There was volcanic activity along this coast as the continents started to spread and the mid-Atlantic ridge began life in this narrow channel. However, Merensky was wrong about the source of the diamonds. These had come from the interior of southern Africa, washed down the Orange River and up the channel, to be deposited along the coastline where the oysters lived. As the channel widened the cold water entered from the south and the oysters died out. The diamond-laden beaches silted and widened for kilometres and additional diamonds were deposited out to sea where they are now mined by dredgers.

Later he drilled for the Free State Goldfields even though they were buried more than a kilometre under the Karoo sediments. Before he died he revealed large deposits of phosphates and copper at Phalaborwa. He was truly the greatest geologist of all time.




Rev 20180907 Copyright (c) 2018 dave (at) howcroft.co.za