Loess ... coming from the wrong direction, and that sinking feeling

17 Nov 2011

The consensus view is that loess, the fine grains of silt that have accumulated in different parts of the world but especially in great big dunes in China, is thought to be wind blown dust from the direction of the Arctic. In the case of China the loess was thought to have blown in from the north west, in the direction of Siberia and presumably the tundra. It seems this interpretation may be up for grabs. Not the theory of course but the origin of the loess. It is thought to derive from dry regions of the planet, and almost everywhere that wasn't frozen in the Ice Age is assumed to have been dry, especially Siberia and the tundra zone below the Arctic. This is mainly because Siberia had no ice sheet - but it must have been cold, that is the theory behind the ice ages, and therefore if it was not frozen that must have been because it was cold and dry and there was not enough moisture to create an ice sheet in Siberia. Simple really. However, a new bit of research that has examined the grains of the silt or loess has discovered they have an origin on the Tibetan plateau and in the Qaidun Basin (north of Tibet), directly west of the Chinese loess deposits (see www.sciencedaily.com/releases/2011/11/111114152537.htm).

The explanation given is that the northern jet stream was not where it is in the modern world. It was further south, hemispherically. However, might it's pathway around the globe have differed, at an angle to what it is now? 

At www.physorg.com/print240662750.html ... there is a story on the discovery of two islands, as big as Tasmania, on the sea floor to the west of Perth in Australia. They are located at the depth of 1.5km below the surface of the Indian Ocean yet rocks were dredged up that indicated these islands were once above sea level - and dry land. The flat tops of the islands further indicates they were above sea level and had been eroded, or planed down, by geological forces. Hence, they were above sea level for some considerable time. However, when the timescale is mentioned it seems we are back in the dinosaur age - when sea levels were quite different to now. At the same time these islands were above sea level large parts of Europe, including most of what is now England, were beneath the waves. At the same point in time there is plenty of evidence that in what is now the Arctic the weather was quite sublime - so what was going on at the Poles?

Another fascinating geological aspect is that these two islands were separated from India and Australia when they broke apart, left stranded in between like bits of rock stuck to the sticky substance beneath the crust, much like the rocky bits you can see along the western seaboard of Britain and Ireland, near the coast yet stranded beyond reach. Can plate tectonics explain this phenomenon? Are the plates moving as they say and is the land being pushed apart with some bits getting stuck in the process? Can all the bits be glued together to recreate Pangea - and what would Pangea have looked like in the dinosaur age if the geoid was completely different and where ocean now exists dry land prevailed and where continents now exist the waters of the deep once covered? Is the consensus science of plate tectonics settled - or is it just another discipline over confident in the cleverness of people that have gone before? Interesting questions - with no answer in the offing.