At https://phys.org/news/2024-10-limestone-iron-reveal-puzzling-extreme.html …. we are told karst formations cover one sixth of the Earth – but not necessarily at the surface. . Karst is a dramatic landscape that is often dotted with caves and towers of bedrock. The mainstream line is that it is slowly sculpted by water over a thousands of years. We are then told karst formations also represent a record of Earth’s past temperature and moisture levels. However, they add, it is challenging to figure out exactly when karst landscapes formed.
Karst is defined by the removal of material – usually limestone. Dating the limestone does not therefore date the formation of the karst. Basically, the towers and caves and holes we see nowadays are what is left behind after water has done what it does. It is assumed karst is formed during very wet periods of climate. Or during massive flooding events, it could be argued. Using iron nodules, or remnants of nodules sticking to the surface of the limestone, appears to be one avenue to arrive at a date. They formed at the same time as the karst – or are what was left behind after the heavy water episode. A new methodology has been used to arrive at the date of the formation, now added to the geological armoury. This method is interesting as they neasure how much helium is produced by natural radioactive decay of tiny amounts of elements such as uranium and thorium within the iron nodules – as well as helium. They used the technique in the karst of the Pinnacle Desert of Western Australia. Acres of limestone pillars. Naturally, using the decay rate of uranium best fits a uniformitarian scenario. It produced a date around 100,000 years ago. As this corresponds roughly with the uniformitarian known date of strata below and above the karst, it comes across as a bullseye. The earth scientists go on to say that the period around 100,000 years ago, was the wettest in Australia over the last half a million years. I thought the date was interesting in another way, as it corresponded to the bottom end of the last interglacial period – or roughly so. Possibly 20,000 years afterwards. There were some unusual climate changes in other parts of the world around this date. They did not of course investigate the possibllity of a catastrophic event – which is always disappointing.
At https://notrickszone.com/2024/10/14/brown-bears-lived-in-the-73n-siberian-arctic-3500-years-ago-today-their-northern-boundary-is-65n/ … a new study shows the Arctic was warmer than it is nowadays as recently as a few thousand years ago. The brown bear, found in permafrost, on what is now a tundra location, has been dated to 3500 years ago. This coincides with what is known as the Minoan Warm Period in the Near and Middle East, as well as Egypt and the Aegean. A date therefore of 1500BC, which coincides with the LB world. It seems that the location of the bear was warm enough to support vegetation – essential for the bear to survive. Nowadays one would have to travel 8 degrees southwards to find a similar temperature and habitat.