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Loess Build Up

3 February 2021
Geology

At https://tallbloke.wordpress.com/2021/02/02/unmatched-dust-storms-raged-o… … another story about dustg. This time, during the frozen landscapes of the last Ice Age. Huge dust storms swirled across the frozen wastes of northern Europe during the coldest periods of the last Ice Age – particularly during the Late Glacial Maximum. This is bound cup again with mainstream theory. This is that loess has on origin in winds sweeping over the tundra and lifting dust up into the air and dropping it down again, elsewhere. It is a theory. Loess, however, is commonly found along river valleys, or on the terraces of former river beds. In the UK one only need look at the various terraces laid down by successive river Thames as it cut its way through the rocks. Early neolithic farmers in Europe followed the loess as it was fertile and easily ploughed with primitive tools. It so happened the Danube valley was a major route of these farmers, from Romania to the northern European plain. One has to wonder how loess was laid down by wind but mostly in watery locations.

The core of the story is a new estimate of sedimentation and cuumulation rates of European loess layers. It is assumed it was laid down in layers, rather than in a smaller series of events. Loess is fine silt sized particles – note the word silt. It is thought it is transported by the wind from dry areas without vegetation such as the end of ice sheets, or the tundra zone, or from deserts – even dried up river beds. However, the particles are primarily silt sized we may further note, not dust sized, as in sands or tills. Sand is not much use for cultivation. It dries out too quickly. One of the more famous areas of loess in southern Britain is Brentford, on the Thames, and the terrace above. It led to a 19th century bounty for local market gardeners, serving the burgeoning population of London. Anything grew in it. All under London overspill housing now but not so long ago a thriving industry. We are told there are layers of paleosols intermixed with the loess layers and these represnt evidence of a mild climate, representing Ice Age interstadials. The Aeolian layers, on the other hand, were depostied during the cold stadials – including dust and silt from dry river and lake beds. However, the word silt pops up  up again, and we may wonder if the layers are actually evidence of turbidy in a watery environment – during ice melt episodes. It is a moot point but the alternative geological theory, as suggested in opposition to mainstream theory, is that loess has an origin in water flow, or flooding events, and therefore with ice melt episodes. No wonder, then, that loess is found primarily in river valleys, where surges of water are a possibility [ice melt at the end of the last Ice Age flowing through the Danuabe to the Black Sea].

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