The oldest glaciers on the planet have been discovered in South Africa. A group of scientists has dated these glaciers to 2.9 billion years ago, and they are located in rocks under the world's largest gold deposits in South Africa.
The tracks suggest that at the time that area was closer to the poles, or that it experienced a previously unknown period of extreme cold. Professor Axel Hofmann of the University of Johannesburg, South Africa and Professor Ilya Bindeman of the University of Oregon have found evidence from the relative concentrations of oxygen isotopes in ancient rocks, as well as physical evidence, showing the presence, in area of their study, of glaciers 2.9 billion years ago.
The oldest glaciers on the planet have been discovered in South Africa
Ilya Bindeman explained: "We have found extremely well preserved glacial deposits near the goldfields of South Africa. This is one of the few areas that remains fairly intact and unchanged from the time of the early Earth.
These deposits are fossilized glacial moraines, which are basically the debris left behind by a glacier as it gradually melts and contracts. These are the oldest moraine deposits ever found. In addition, we were able to correlate them with oxygen isotope analysis of these rocks, which showed that the climate must have been cold when the rocks were deposited.
We looked at the relative amounts of 3 oxygen isotopes, 16 O, 17 O and 18 O. These are all types of oxygen but have slightly different weights. We found that these rocks had very low 18 O and very high 17 O, indicating they formed at freezing temperatures.
That means ice. Couple that geochemical evidence with moraine evidence, and it means glaciers, the oldest glaciers ever found on Earth. " Hofmann told about: "It may be that this area was near the poles. Another possibility is that the whole Earth was in a freezing period of much of the planet." The researchers findings were presented at the Goldschmidt geochemistry conference in Lyon.
Scientists generally agree that there must have been large variations in the early Earth's climate, but it has been difficult to find concrete evidence that clarifies what exactly the planet's climatic conditions were like at the time.