At https://phys.org/news/2026-03-sediment-core-reveals-years-precipitation.html … a sediment core from the Sahara. Well, from an oasis lake in Chad. We more or less know that rainfall in the Sahara was high in the early Holocene, dipped in the middle of the Holocene, and the Sahara became very dry for the last four thousand or so years ago. The sediment core shows that between 14,800 and 5,500 years ago, the Sahara had good precipitation levels. It is described as a wet phase. However, what caught my eye was that the sediment cores captured evidence of short term droughts. These came around 9,300, 8200 and 6300 years ago. The 8200 years ago drought, following on from the 6200BC ‘event’ seems to have lasted 77 years. In Chad. Remarkaby, all three drought episodes coincide with catastrophic events via counting annuals layers in the sediment core. This raises some mischief in that it appears to contradict the IntCal calibrations in favour at the moment. It goes back to the old tree ring and C14 calibration model – or at least, to the last event as far as Belfast is concerned. In years BC we have 4300, 6200 and 7300BC. The latter is perhaps associated with the spurt in sea level that led to the drowning of the land connection between Ireland and Britain, but more certainly with the drowning of the upper basin of the North Sea – creating the Shetlands and Orkneys as islands. The middle date coincides with the collapse of the Storegga Shelf off Norway – affecting Scotland and northern England [tidal wave], while the former appears to coincide with the arrival in Britain of its first farmer colonisation from the opposite side of the North Sea. Did they arrive by boat or island hop?
Unfortunately it persists with the idea that the 6200BC event was caused by an influx of fresh water by the emptying of a lake somewhere in North America formed after the Late Glacial Maximum. What would cause a lake to suddenly empty – on the assumption they have found a lake to fulfill that purpose. Well, the 6200BC event was followed by the Mid Holocene Warm Period – which may provide a clue.