About 75,000 years ago, an immense volcanic eruption occurred in Mt. Toba on the island of Sumatra, in an explosion estimated between 10 and 360 times that of Mt. Pinatubo. Thick ash layers covered much of India and parts of Asia, and ash and aerosols were injected into the atmosphere, creating what must have been devastating environmental effects. But... were the environmental effects world wide?
YTT ash extracted from the Malawi sediment cores. The ash is composed of tiny glass shards, visible only under a microscope, formed from the rapid freezing of magma ejected from the Toba volcano during the eruption." Credit: Christine Lane
These tiny sherds of volcanic glass come from about 30 meters (~100 ft) below the surface of Lake Malawi, a narrow lake in east Africa that lies partly within the countries of Malawi, Mozambique and Tanzania. These flakes and their sediments were reported in the Proceedings of the National Academy of Sciences on April 29, 2013; and they provide an intriguing archaeological record of the super-eruption.
The impacts of the "Toba Super-Eruption" have been traced in Greenland ice cores, and the atmospheric injecta are considered responsible for the onset of the cool period Marine Isotope Stage 4; and MIS4 is widely considered responsible for a recognized genetic "human bottleneck" which led to our eventually migrating out of Africa. The evidence from Lake Malawi, however, seems to indicate that there was no large environmental shakeup in east Africa ~75,000 years ago. Doesn't mean there wasn't a bottleneck, or there wasn't a super-eruption: but it may help us understand the effects of such super-eruptions on a wider scale.
- Read more about the Toba Volcano, including a summary of the current research
- Jwalapuram, India, where the ash fall from the Mt. Toba eruption was up to 25 feet thick
Lane CS, Chorn BT, and Johnson TC. 2013. Ash from the Toba supereruption in Lake Malawi shows no volcanic winter in East Africa at 75 ka. Proceedings of the National Academy of Sciences Early edition.
Comments
The evidence of toba ash during the erruption of mt toba 75,000 years ago could still be found at Lenggong valley the World Heritage Site at Perak, Malaysia. It could easily been seen if you visit Bukit Sapi at the WH site.
I was very interested in your article on the eruption of Toba. This event and its aftermath figures largely in some research on adapation to fresh milk (LP ability) I have been doing for a few years now.
My conclusion was that adult lactase persistence evolved by drastic selection out of the normal background 3-4 per cent to 100 per cent during the volcanic winter following the eruption of Toba which comes at exactly the right time (in my view) and that this 100 per cent milking population went on to settle Europe. Not before the Moderns left Africa but a long time after. At that point they were in the Urals, or thereabouts. Those who survived did so by milking available animals, either reindeer or cattle (aurochs).
All the known facts fit with this thesis though it does not allow current hypotheses about time of settlement, genetic evolution, history of domestication etc etc.
how its possible to deposit ash such a 25 fit thick..in jwalapuram.