The diggings of Nooitgedacht
Since 1869 the various gravels along the Vaal River have been worked intensively for their content of high-grade alluvial diamonds. The Nooitgedacht diggings were opened in 1949 and closed in 1981. During these 32 years, a total of 80 000 diamonds were found. The Venter Diamond, a 511 carat yellow stone, was the largest.
The standard size of a digger's claim was 15 x 15 metres. The diamond-bearing gravels, covered by a layer of sterile red sand, were washed by hand in simple rotary pans. The left-over concentrate of heavy material was then carefully sorted for diamonds.
The search for diamonds continues along the Vaal River between Windsorton, Barkly West and Delportshoop. Some small-scale diggers still use pick and shovel, but diggers using heavy earth-moving equipment obtain better returns.
This rock is the result of volcanic eruptions 2300 million years ago. Molten rock rose from the earth's interior and solidified as it cooled. At that time life on earth was confined to single-celled organisms.
A consolidated mixture of mud and rock deposited by glaciers 290 million years ago during the Dwyka Ice Age. Life forms then were primitive insects, reptiles and plants.
These were deposited by wind and water during the past 25 million years. Mammals evolved concurrently but humans have appeared only in the last 5 million years.
The earth's changing surface
380 million years ago three great continents existed. 180 million years ago these three continents drifted together to form a single supercontinent, Pangea. This vast landmass subsequently broke up and the separated continents gradually drifted to their present positions. The process, called plate techtonics, is still continuing and satellite measurements show that Africa and South America are moving apart by 2 cm every year.
A long past ice age
290 Million years ago, during Dwyka times, Southern Africa was near the South Pole and large ice sheets or glaciers covered high-lying areas. As the glaciers moved, the rocks and rubble that became embedded in their undersurface scoured out scratch marks, known as striations, on the underlying Andesite rock pavements. When the glaciers eventually melted, a mixture of clay and rock was left behind and consolidated into a rock called Tillite.
River of diamonds
Along this portion of its course, the Vaal has cut through and swept away a vast mass of Karoo sediment, to re-expose the volcanic Andesite landscape formed 2300 million years ago. The following four groups of deposits have been laid down by the river during Tertiary and Quaternary times:
The Older Gravels
These diamond-bearing deposits occur 60-20 metres above the river-bed and were possibly deposited 24,0 to 1,6 million years ago.
The Younger Gravels
These gravels which are also diamond-bearing, range up to 15 metres above the river-bed and contain Stone Age tools and fossil animal bones of 700-130 thousand years ago.
The Riverton Formation
This is typically represented by silt levees and flats skirting the present-day channel of the Vaal. Stone tools found in these sediments suggest that they were probably deposited 130 000 to 10 000 years ago.
The Red Sands
Apparently wind-blown, these deposits mantle the Younger Gravels and the Riverton Formation in places. Stone tools found on the farm Nooitgedacht suggest that the red sand accumulated about 100 000 to 50 000 years ago.
Permanent water and an abundance of game made this stretch of the VaaI an ideal area for human occupation at various times in the past. Archaeological Sites within a few kilometres of the Nooitgedacht exhibit include:
Numerous Earlier Stone Age occurrences (1,5 million to 200 000 B.C.)
Various Middle Stone Age scatters (120 000 to 70 000 B.C.)
Extensive Later Stone Age spreads with pottery (1000 to I500 A.D.)
Later Stone Age burials (1000 to 1500 A.D.)
Rock art sites possibly corresponding in age with Later Stone Age sites.
Occasional stone circles and stone-covered rectangular graves (19th Century)
The pictures found on the Andesite glacial pavements at Nooitgedacht are called engravings that were produced by pecking out the outlines with a pointed stone. They ware probably made by Khoisan people during the past thousand years. The naturalistic engravings include humans, giraffe, rhinoceros, ostrich, anteater and eland while abstract forms are mainly spirals and grids of unknown meaning.