At https://phys.org/news/2025-05-year-cave-sediments-alaskan-island.html … cave sediments going back to the Late Glacial Maximum, around 20,000 years ago, provide new clues on climate and the environment, back then. Meltwater pulses from the Cordillera ice sheet, which reached its maximum extent 20,000 years ago, are said to feature. The ice melted over the next few thousand years – but the energy required for this is difficult to correlate with known changes in temperature. That is a remarkable statement, we may note. So how warm must it have got in order to melt the Cordillera ice sheet – basically, glaciers across Alaskan and Canadian mountain chains. They still exist in the modern world but it is thought they were much more extensive in the LGM. Have they found evidence of rapid ice melt? The cave itself is located on Prince of Wales Island in Alaska. The sediment contained no organic debris – which was odd.
The sediments, it is said, date between 20,000 and 17,000 years ago – at the very end of the Late Glacial Maximum. Hence, they are thought to be the result of meltwater from a receding ice sheet. However, if Alaska was warmer than currently allowed, could the water have a different origin? The inference is that the sediments were laid by water – and the lack of organic content should provide us with a clue. For the full research paper see https://doi.org/10.1038/s41561-025-01694-4 …
At https://www.livescience.com/planet-earth/geology/gigantic-mud-waves-buried-deep-beneath-the-ocean-floor-reveal-dramatic-formation-of-atlantic-when-africa-and-south-america-finally-split … enormous mud waves, it seems, buried under the Atlantic seabed, off the coast of Africa, are hundreds of feet high – and almost a mile long. They are said to date back 117 million years ago – when the Atlantic Ocean is thought to have first opened.